719 lines
25 KiB
Java
719 lines
25 KiB
Java
/* Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation
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This file is part of libgcj.
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This software is copyrighted work licensed under the terms of the
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Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
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details. */
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package java.io;
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/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
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* "The Java Language Specification", ISBN 0-201-63451-1
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* plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
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* Status: Believed complete and correct.
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*/
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/**
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* This subclass of <code>FilteredInputStream</code> implements the
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* <code>DataInput</code> interface that provides method for reading primitive
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* Java data types from a stream.
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*
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* @see DataInput
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*
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* @version 0.0
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*
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* @author Warren Levy <warrenl@cygnus.com>
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* @author Aaron M. Renn (arenn@urbanophile.com)
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* @date October 20, 1998.
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*/
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public class DataInputStream extends FilterInputStream implements DataInput
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{
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// readLine() hack to ensure that an '\r' not followed by an '\n' is
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// handled correctly. If set, readLine() will ignore the first char it sees
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// if that char is a '\n'
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boolean ignoreInitialNewline = false;
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/**
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* This constructor initializes a new <code>DataInputStream</code>
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* to read from the specified subordinate stream.
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*
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* @param in The subordinate <code>InputStream</code> to read from
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*/
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public DataInputStream(InputStream in)
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{
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super(in);
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}
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/**
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* This method reads bytes from the underlying stream into the specified
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* byte array buffer. It will attempt to fill the buffer completely, but
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* may return a short count if there is insufficient data remaining to be
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* read to fill the buffer.
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*
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* @param b The buffer into which bytes will be read.
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*
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* @return The actual number of bytes read, or -1 if end of stream reached
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* before reading any bytes.
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*
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* @exception IOException If an error occurs.
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*/
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public final int read(byte[] b) throws IOException
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{
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return in.read(b, 0, b.length);
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}
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/**
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* This method reads bytes from the underlying stream into the specified
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* byte array buffer. It will attempt to read <code>len</code> bytes and
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* will start storing them at position <code>off</code> into the buffer.
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* This method can return a short count if there is insufficient data
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* remaining to be read to complete the desired read length.
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*
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* @param b The buffer into which bytes will be read.
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* @param off The offset into the buffer to start storing bytes.
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* @param len The requested number of bytes to read.
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*
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* @return The actual number of bytes read, or -1 if end of stream reached
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* before reading any bytes.
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*
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* @exception IOException If an error occurs.
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*/
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public final int read(byte[] b, int off, int len) throws IOException
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{
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return in.read(b, off, len);
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}
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/**
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* This method reads a Java boolean value from an input stream. It does
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* so by reading a single byte of data. If that byte is zero, then the
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* value returned is <code>false</code>. If the byte is non-zero, then
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* the value returned is <code>true</code>.
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* <p>
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* This method can read a <code>boolean</code> written by an object
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* implementing the <code>writeBoolean()</code> method in the
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* <code>DataOutput</code> interface.
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*
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* @return The <code>boolean</code> value read
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*
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* @exception EOFException If end of file is reached before reading
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* the boolean
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* @exception IOException If any other error occurs
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*/
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public final boolean readBoolean() throws IOException
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{
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int b = in.read();
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if (b < 0)
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throw new EOFException();
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return (b != 0);
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}
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/**
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* This method reads a Java byte value from an input stream. The value
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* is in the range of -128 to 127.
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* <p>
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* This method can read a <code>byte</code> written by an object
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* implementing the <code>writeByte()</code> method in the
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* <code>DataOutput</code> interface.
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*
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* @return The <code>byte</code> value read
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*
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* @exception EOFException If end of file is reached before reading the byte
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* @exception IOException If any other error occurs
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*
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* @see DataOutput
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*/
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public final byte readByte() throws IOException
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{
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int i = in.read();
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if (i < 0)
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throw new EOFException();
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return (byte) i;
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}
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/**
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* This method reads a Java <code>char</code> value from an input stream.
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* It operates by reading two bytes from the stream and converting them to
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* a single 16-bit Java <code>char</code>. The two bytes are stored most
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* significant byte first (i.e., "big endian") regardless of the native
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* host byte ordering.
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* <p>
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* As an example, if <code>byte1</code> and <code>byte2</code>
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* represent the first and second byte read from the stream
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* respectively, they will be transformed to a <code>char</code> in
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* the following manner:
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* <p>
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* <code>(char)(((byte1 & 0xFF) << 8) | (byte2 & 0xFF)</code>
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* <p>
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* This method can read a <code>char</code> written by an object
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* implementing the <code>writeChar()</code> method in the
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* <code>DataOutput</code> interface.
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*
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* @return The <code>char</code> value read
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*
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* @exception EOFException If end of file is reached before reading the char
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* @exception IOException If any other error occurs
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*
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* @see DataOutput
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*/
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public final char readChar() throws IOException
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{
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int a = in.read();
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int b = in.read();
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if (b < 0)
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throw new EOFException();
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return (char) ((a << 8) | (b & 0xff));
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}
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/**
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* This method reads a Java double value from an input stream. It operates
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* by first reading a <code>long</code> value from the stream by calling the
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* <code>readLong()</code> method in this interface, then converts
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* that <code>long</code> to a <code>double</code> using the
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* <code>longBitsToDouble</code> method in the class
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* <code>java.lang.Double</code>
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* <p>
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* This method can read a <code>double</code> written by an object
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* implementing the <code>writeDouble()</code> method in the
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* <code>DataOutput</code> interface.
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*
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* @return The <code>double</code> value read
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*
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* @exception EOFException If end of file is reached before reading
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* the double
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* @exception IOException If any other error occurs
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*
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* @see java.lang.Double
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* @see DataOutput
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*/
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public final double readDouble() throws IOException
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{
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return Double.longBitsToDouble(readLong());
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}
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/**
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* This method reads a Java float value from an input stream. It
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* operates by first reading an <code>int</code> value from the
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* stream by calling the <code>readInt()</code> method in this
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* interface, then converts that <code>int</code> to a
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* <code>float</code> using the <code>intBitsToFloat</code> method
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* in the class <code>java.lang.Float</code>
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* <p>
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* This method can read a <code>float</code> written by an object
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* implementing the * <code>writeFloat()</code> method in the
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* <code>DataOutput</code> interface.
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*
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* @return The <code>float</code> value read
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*
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* @exception EOFException If end of file is reached before reading the float
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* @exception IOException If any other error occurs
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*
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* @see java.lang.Float
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* @see DataOutput */
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public final float readFloat() throws IOException
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{
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return Float.intBitsToFloat(readInt());
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}
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/**
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* This method reads raw bytes into the passed array until the array is
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* full. Note that this method blocks until the data is available and
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* throws an exception if there is not enough data left in the stream to
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* fill the buffer
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*
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* @param b The buffer into which to read the data
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*
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* @exception EOFException If end of file is reached before filling
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* the buffer
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* @exception IOException If any other error occurs */
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public final void readFully(byte[] b) throws IOException
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{
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readFully(b, 0, b.length);
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}
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/**
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* This method reads raw bytes into the passed array
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* <code>buf</code> starting <code>offset</code> bytes into the
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* buffer. The number of bytes read will be exactly
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* <code>len</code> Note that this method blocks until the data is
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* available and * throws an exception if there is not enough data
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* left in the stream to read <code>len</code> bytes.
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*
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* @param buf The buffer into which to read the data
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* @param offset The offset into the buffer to start storing data
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* @param len The number of bytes to read into the buffer
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*
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* @exception EOFException If end of file is reached before filling
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* the buffer
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* @exception IOException If any other error occurs
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*/
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public final void readFully(byte[] b, int off, int len) throws IOException
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{
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while (len > 0)
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{
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// in.read will block until some data is available.
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int numread = in.read(b, off, len);
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if (numread < 0)
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throw new EOFException();
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len -= numread;
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off += numread;
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}
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}
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/**
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* This method reads a Java <code>int</code> value from an input
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* stream It operates by reading four bytes from the stream and
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* converting them to a single Java <code>int</code> The bytes are
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* stored most significant byte first (i.e., "big endian")
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* regardless of the native host byte ordering.
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* <p>
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* As an example, if <code>byte1</code> through <code>byte4</code>
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* represent the first four bytes read from the stream, they will be
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* transformed to an <code>int</code> in the following manner:
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* <p>
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* <code>(int)(((byte1 & 0xFF) << 24) + ((byte2 & 0xFF) << 16) +
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* ((byte3 & 0xFF) << 8) + (byte4 & 0xFF)))</code>
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* <p>
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* The value returned is in the range of 0 to 65535.
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* <p>
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* This method can read an <code>int</code> written by an object
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* implementing the <code>writeInt()</code> method in the
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* <code>DataOutput</code> interface.
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*
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* @return The <code>int</code> value read
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*
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* @exception EOFException If end of file is reached before reading the int
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* @exception IOException If any other error occurs
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*
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* @see DataOutput
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*/
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public final int readInt() throws IOException
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{
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int a = in.read();
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int b = in.read();
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int c = in.read();
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int d = in.read();
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if (d < 0)
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throw new EOFException();
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return (((a & 0xff) << 24) | ((b & 0xff) << 16) |
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((c & 0xff) << 8) | (d & 0xff));
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}
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/**
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* This method reads the next line of text data from an input
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* stream. It operates by reading bytes and converting those bytes
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* to <code>char</code> values by treating the byte read as the low
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* eight bits of the <code>char</code> and using 0 as the high eight
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* bits. Because of this, it does not support the full 16-bit
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* Unicode character set.
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* <p>
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* The reading of bytes ends when either the end of file or a line
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* terminator is encountered. The bytes read are then returned as a
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* <code>String</code> A line terminator is a byte sequence
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* consisting of either <code>\r</code>, <code>\n</code> or
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* <code>\r\n</code>. These termination charaters are discarded and
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* are not returned as part of the string.
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* <p>
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* This method can read data that was written by an object implementing the
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* <code>writeLine()</code> method in <code>DataOutput</code>.
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*
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* @return The line read as a <code>String</code>
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*
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* @exception IOException If an error occurs
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*
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* @see DataOutput
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*
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* @deprecated
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*/
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public final String readLine() throws IOException
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{
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StringBuffer strb = new StringBuffer();
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readloop: while (true)
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{
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int c = 0;
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char ch = ' ';
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boolean getnext = true;
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while (getnext)
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{
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getnext = false;
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c = in.read();
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if (c < 0) // got an EOF
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return strb.length() > 0 ? strb.toString() : null;
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ch = (char) c;
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if ((ch &= 0xFF) == '\n')
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// hack to correctly handle '\r\n' sequences
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if (ignoreInitialNewline)
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{
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ignoreInitialNewline = false;
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getnext = true;
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}
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else
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break readloop;
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}
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if (ch == '\r')
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{
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// FIXME: The following code tries to adjust the stream back one
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// character if the next char read is '\n'. As a last resort,
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// it tries to mark the position before reading but the bottom
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// line is that it is possible that this method will not properly
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// deal with a '\r' '\n' combination thus not fulfilling the
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// DataInput contract for readLine. It's not a particularly
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// safe approach threadwise since it is unsynchronized and
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// since it might mark an input stream behind the users back.
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// Along the same vein it could try the same thing for
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// ByteArrayInputStream and PushbackInputStream, but that is
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// probably overkill since this is deprecated & BufferedInputStream
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// is the most likely type of input stream.
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//
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// The alternative is to somehow push back the next byte if it
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// isn't a '\n' or to have the reading methods of this class
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// keep track of whether the last byte read was '\r' by readLine
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// and then skip the very next byte if it is '\n'. Either way,
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// this would increase the complexity of the non-deprecated methods
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// and since it is undesirable to make non-deprecated methods
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// less efficient, the following seems like the most reasonable
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// approach.
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int next_c = 0;
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char next_ch = ' ';
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if (in instanceof BufferedInputStream)
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{
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next_c = in.read();
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next_ch = (char) (next_c & 0xFF);
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if ((next_ch != '\n') && (next_c >= 0))
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{
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BufferedInputStream bin = (BufferedInputStream) in;
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if (bin.pos > 0)
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bin.pos--;
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}
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}
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else if (markSupported())
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{
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next_c = in.read();
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next_ch = (char) (next_c & 0xFF);
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if ((next_ch != '\n') && (next_c >= 0))
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{
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mark(1);
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if ((in.read() & 0xFF) != '\n')
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reset();
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}
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}
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// In order to catch cases where 'in' isn't a BufferedInputStream
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// and doesn't support mark() (such as reading from a Socket), set
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// a flag that instructs readLine() to ignore the first character
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// it sees _if_ that character is a '\n'.
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else ignoreInitialNewline = true;
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break;
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}
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strb.append(ch);
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}
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return strb.length() > 0 ? strb.toString() : "";
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}
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/**
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* This method reads a Java long value from an input stream
|
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* It operates by reading eight bytes from the stream and converting them to
|
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* a single Java <code>long</code> The bytes are stored most
|
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* significant byte first (i.e., "big endian") regardless of the native
|
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* host byte ordering.
|
|
* <p>
|
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* As an example, if <code>byte1</code> through <code>byte8</code>
|
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* represent the first eight bytes read from the stream, they will
|
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* be transformed to an <code>long</code> in the following manner:
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* <p>
|
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* <code>(long)((((long)byte1 & 0xFF) << 56) + (((long)byte2 & 0xFF) << 48) +
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* (((long)byte3 & 0xFF) << 40) + (((long)byte4 & 0xFF) << 32) +
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* (((long)byte5 & 0xFF) << 24) + (((long)byte6 & 0xFF) << 16) +
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* (((long)byte7 & 0xFF) << 8) + ((long)byte9 & 0xFF)))</code>
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* <p>
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* The value returned is in the range of 0 to 65535.
|
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* <p>
|
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* This method can read an <code>long</code> written by an object
|
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* implementing the <code>writeLong()</code> method in the
|
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* <code>DataOutput</code> interface.
|
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*
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* @return The <code>long</code> value read
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*
|
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* @exception EOFException If end of file is reached before reading the long
|
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* @exception IOException If any other error occurs
|
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*
|
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* @see DataOutput
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*/
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public final long readLong() throws IOException
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{
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int a = in.read();
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int b = in.read();
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int c = in.read();
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int d = in.read();
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int e = in.read();
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int f = in.read();
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int g = in.read();
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int h = in.read();
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if (h < 0)
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throw new EOFException();
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return (((long)(a & 0xff) << 56) |
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((long)(b & 0xff) << 48) |
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((long)(c & 0xff) << 40) |
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((long)(d & 0xff) << 32) |
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((long)(e & 0xff) << 24) |
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((long)(f & 0xff) << 16) |
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((long)(g & 0xff) << 8) |
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((long)(h & 0xff)));
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}
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|
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/**
|
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* This method reads a signed 16-bit value into a Java in from the
|
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* stream. It operates by reading two bytes from the stream and
|
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* converting them to a single 16-bit Java <code>short</code>. The
|
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* two bytes are stored most significant byte first (i.e., "big
|
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* endian") regardless of the native host byte ordering.
|
|
* <p>
|
|
* As an example, if <code>byte1</code> and <code>byte2</code>
|
|
* represent the first and second byte read from the stream
|
|
* respectively, they will be transformed to a <code>short</code>. in
|
|
* the following manner:
|
|
* <p>
|
|
* <code>(short)(((byte1 & 0xFF) << 8) | (byte2 & 0xFF)</code>
|
|
* <p>
|
|
* The value returned is in the range of -32768 to 32767.
|
|
* <p>
|
|
* This method can read a <code>short</code> written by an object
|
|
* implementing the <code>writeShort()</code> method in the
|
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* <code>DataOutput</code> interface.
|
|
*
|
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* @return The <code>short</code> value read
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|
*
|
|
* @exception EOFException If end of file is reached before reading the value
|
|
* @exception IOException If any other error occurs
|
|
*
|
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* @see DataOutput
|
|
*/
|
|
public final short readShort() throws IOException
|
|
{
|
|
int a = in.read();
|
|
int b = in.read();
|
|
if (b < 0)
|
|
throw new EOFException();
|
|
return (short) ((a << 8) | (b & 0xff));
|
|
}
|
|
|
|
/**
|
|
* This method reads 8 unsigned bits into a Java <code>int</code>
|
|
* value from the stream. The value returned is in the range of 0 to
|
|
* 255.
|
|
* <p>
|
|
* This method can read an unsigned byte written by an object
|
|
* implementing the <code>writeUnsignedByte()</code> method in the
|
|
* <code>DataOutput</code> interface.
|
|
*
|
|
* @return The unsigned bytes value read as a Java <code>int</code>.
|
|
*
|
|
* @exception EOFException If end of file is reached before reading the value
|
|
* @exception IOException If any other error occurs
|
|
*
|
|
* @see DataOutput
|
|
*/
|
|
public final int readUnsignedByte() throws IOException
|
|
{
|
|
int i = in.read();
|
|
if (i < 0)
|
|
throw new EOFException();
|
|
|
|
return (i & 0xFF);
|
|
}
|
|
|
|
/**
|
|
* This method reads 16 unsigned bits into a Java int value from the stream.
|
|
* It operates by reading two bytes from the stream and converting them to
|
|
* a single Java <code>int</code> The two bytes are stored most
|
|
* significant byte first (i.e., "big endian") regardless of the native
|
|
* host byte ordering.
|
|
* <p>
|
|
* As an example, if <code>byte1</code> and <code>byte2</code>
|
|
* represent the first and second byte read from the stream
|
|
* respectively, they will be transformed to an <code>int</code> in
|
|
* the following manner:
|
|
* <p>
|
|
* <code>(int)(((byte1 & 0xFF) << 8) + (byte2 & 0xFF))</code>
|
|
* <p>
|
|
* The value returned is in the range of 0 to 65535.
|
|
* <p>
|
|
* This method can read an unsigned short written by an object
|
|
* implementing the <code>writeUnsignedShort()</code> method in the
|
|
* <code>DataOutput</code> interface.
|
|
*
|
|
* @return The unsigned short value read as a Java <code>int</code>
|
|
*
|
|
* @exception EOFException If end of file is reached before reading the value
|
|
* @exception IOException If any other error occurs
|
|
*/
|
|
public final int readUnsignedShort() throws IOException
|
|
{
|
|
int a = in.read();
|
|
int b = in.read();
|
|
if (b < 0)
|
|
throw new EOFException();
|
|
return (((a & 0xff) << 8) | (b & 0xff));
|
|
}
|
|
|
|
/**
|
|
* This method reads a <code>String</code> from an input stream that
|
|
* is encoded in a modified UTF-8 format. This format has a leading
|
|
* two byte sequence that contains the remaining number of bytes to
|
|
* read. This two byte sequence is read using the
|
|
* <code>readUnsignedShort()</code> method of this interface.
|
|
* <p>
|
|
* After the number of remaining bytes have been determined, these
|
|
* bytes are read an transformed into <code>char</code> values.
|
|
* These <code>char</code> values are encoded in the stream using
|
|
* either a one, two, or three byte format. The particular format
|
|
* in use can be determined by examining the first byte read.
|
|
* <p>
|
|
* If the first byte has a high order bit of 0, then that character
|
|
* consists on only one byte. This character value consists of
|
|
* seven bits that are at positions 0 through 6 of the byte. As an
|
|
* example, if <code>byte1</code> is the byte read from the stream,
|
|
* it would be converted to a <code>char</code> like so:
|
|
* <p>
|
|
* <code>(char)byte1</code>
|
|
* <p>
|
|
* If the first byte has 110 as its high order bits, then the
|
|
* character consists of two bytes. The bits that make up the character
|
|
* value are in positions 0 through 4 of the first byte and bit positions
|
|
* 0 through 5 of the second byte. (The second byte should have
|
|
* 10 as its high order bits). These values are in most significant
|
|
* byte first (i.e., "big endian") order.
|
|
* <p>
|
|
* As an example, if <code>byte1</code> and <code>byte2</code> are
|
|
* the first two bytes read respectively, and the high order bits of
|
|
* them match the patterns which indicate a two byte character
|
|
* encoding, then they would be converted to a Java
|
|
* <code>char</code> like so:
|
|
* <p>
|
|
* <code>(char)(((byte1 & 0x1F) << 6) | (byte2 & 0x3F))</code>
|
|
* <p>
|
|
* If the first byte has a 1110 as its high order bits, then the
|
|
* character consists of three bytes. The bits that make up the character
|
|
* value are in positions 0 through 3 of the first byte and bit positions
|
|
* 0 through 5 of the other two bytes. (The second and third bytes should
|
|
* have 10 as their high order bits). These values are in most
|
|
* significant byte first (i.e., "big endian") order.
|
|
* <p>
|
|
* As an example, if <code>byte1</code> <code>byte2</code> and
|
|
* <code>byte3</code> are the three bytes read, and the high order
|
|
* bits of them match the patterns which indicate a three byte
|
|
* character encoding, then they would be converted to a Java
|
|
* <code>char</code> like so:
|
|
* <p>
|
|
* <code>(char)(((byte1 & 0x0F) << 12) | ((byte2 & 0x3F) << 6) | (byte3 & 0x3F))</code>
|
|
* <p>
|
|
* Note that all characters are encoded in the method that requires
|
|
* the fewest number of bytes with the exception of the character
|
|
* with the value of <code>\u0000</code> which is encoded as two
|
|
* bytes. This is a modification of the UTF standard used to
|
|
* prevent C language style <code>NUL</code> values from appearing
|
|
* in the byte stream.
|
|
* <p>
|
|
* This method can read data that was written by an object implementing the
|
|
* <code>writeUTF()</code> method in <code>DataOutput</code>
|
|
*
|
|
* @returns The <code>String</code> read
|
|
*
|
|
* @exception EOFException If end of file is reached before reading
|
|
* the String
|
|
* @exception UTFDataFormatException If the data is not in UTF-8 format
|
|
* @exception IOException If any other error occurs
|
|
*
|
|
* @see DataOutput
|
|
*/
|
|
public final String readUTF() throws IOException
|
|
{
|
|
return readUTF(this);
|
|
}
|
|
|
|
/**
|
|
* This method reads a String encoded in UTF-8 format from the
|
|
* specified <code>DataInput</code> source.
|
|
*
|
|
* @param in The <code>DataInput</code> source to read from
|
|
*
|
|
* @return The String read from the source
|
|
*
|
|
* @exception IOException If an error occurs
|
|
*/
|
|
public final static String readUTF(DataInput in) throws IOException
|
|
{
|
|
final int UTFlen = in.readUnsignedShort();
|
|
byte[] buf = new byte[UTFlen];
|
|
StringBuffer strbuf = new StringBuffer();
|
|
|
|
// This blocks until the entire string is available rather than
|
|
// doing partial processing on the bytes that are available and then
|
|
// blocking. An advantage of the latter is that Exceptions
|
|
// could be thrown earlier. The former is a bit cleaner.
|
|
in.readFully(buf, 0, UTFlen);
|
|
for (int i = 0; i < UTFlen; )
|
|
{
|
|
if ((buf[i] & 0x80) == 0) // bit pattern 0xxxxxxx
|
|
strbuf.append((char) (buf[i++] & 0xFF));
|
|
else if ((buf[i] & 0xE0) == 0xC0) // bit pattern 110xxxxx
|
|
{
|
|
if (i + 1 >= UTFlen || (buf[i+1] & 0xC0) != 0x80)
|
|
throw new UTFDataFormatException();
|
|
|
|
strbuf.append((char) (((buf[i++] & 0x1F) << 6) |
|
|
(buf[i++] & 0x3F)));
|
|
}
|
|
else if ((buf[i] & 0xF0) == 0xE0) // bit pattern 1110xxxx
|
|
{
|
|
if (i + 2 >= UTFlen ||
|
|
(buf[i+1] & 0xC0) != 0x80 || (buf[i+2] & 0xC0) != 0x80)
|
|
throw new UTFDataFormatException();
|
|
|
|
strbuf.append((char) (((buf[i++] & 0x0F) << 12) |
|
|
((buf[i++] & 0x3F) << 6) |
|
|
(buf[i++] & 0x3F)));
|
|
}
|
|
else // must be ((buf[i] & 0xF0) == 0xF0 || (buf[i] & 0xC0) == 0x80)
|
|
throw new UTFDataFormatException(); // bit patterns 1111xxxx or
|
|
// 10xxxxxx
|
|
}
|
|
|
|
return strbuf.toString();
|
|
}
|
|
|
|
/**
|
|
* This method attempts to skip and discard the specified number of bytes
|
|
* in the input stream. It may actually skip fewer bytes than requested.
|
|
* This method will not skip any bytes if passed a negative number of bytes
|
|
* to skip.
|
|
*
|
|
* @param n The requested number of bytes to skip.
|
|
* @return The requested number of bytes to skip.
|
|
* @exception IOException If an error occurs.
|
|
* @specnote The JDK docs claim that this returns the number of bytes
|
|
* actually skipped. The JCL claims that this method can throw an
|
|
* EOFException. Neither of these appear to be true in the JDK 1.3's
|
|
* implementation. This tries to implement the actual JDK behaviour.
|
|
*/
|
|
public final int skipBytes(int n) throws IOException
|
|
{
|
|
if (n <= 0)
|
|
return 0;
|
|
try
|
|
{
|
|
return (int) in.skip(n);
|
|
}
|
|
catch (EOFException x)
|
|
{
|
|
// do nothing.
|
|
}
|
|
return n;
|
|
}
|
|
}
|