-/* Copyright (C) 1998, 1999 Free Software Foundation
+/* Copyright (C) 1998, 1999, 2000 Free Software Foundation
This file is part of libgcj.
package java.io;
-/**
- * @author Warren Levy <warrenl@cygnus.com>
- * @date October 20, 1998.
- */
-
/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
* "The Java Language Specification", ISBN 0-201-63451-1
* plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
* Status: Believed complete and correct.
*/
+/**
+ * This subclass of <code>FilteredInputStream</code> implements the
+ * <code>DataInput</code> interface that provides method for reading primitive
+ * Java data types from a stream.
+ *
+ * @see DataInput
+ *
+ * @version 0.0
+ *
+ * @author Warren Levy <warrenl@cygnus.com>
+ * @author Aaron M. Renn (arenn@urbanophile.com)
+ * @date October 20, 1998.
+ */
+
public class DataInputStream extends FilterInputStream implements DataInput
{
// readLine() hack to ensure that an '\r' not followed by an '\n' is
// if that char is a '\n'
boolean ignoreInitialNewline = false;
+ /**
+ * This constructor initializes a new <code>DataInputStream</code>
+ * to read from the specified subordinate stream.
+ *
+ * @param in The subordinate <code>InputStream</code> to read from
+ */
public DataInputStream(InputStream in)
{
super(in);
}
+ /**
+ * This method reads bytes from the underlying stream into the specified
+ * byte array buffer. It will attempt to fill the buffer completely, but
+ * may return a short count if there is insufficient data remaining to be
+ * read to fill the buffer.
+ *
+ * @param b The buffer into which bytes will be read.
+ *
+ * @return The actual number of bytes read, or -1 if end of stream reached
+ * before reading any bytes.
+ *
+ * @exception IOException If an error occurs.
+ */
public final int read(byte[] b) throws IOException
{
return super.read(b, 0, b.length);
}
+ /**
+ * This method reads bytes from the underlying stream into the specified
+ * byte array buffer. It will attempt to read <code>len</code> bytes and
+ * will start storing them at position <code>off</code> into the buffer.
+ * This method can return a short count if there is insufficient data
+ * remaining to be read to complete the desired read length.
+ *
+ * @param b The buffer into which bytes will be read.
+ * @param off The offset into the buffer to start storing bytes.
+ * @param len The requested number of bytes to read.
+ *
+ * @return The actual number of bytes read, or -1 if end of stream reached
+ * before reading any bytes.
+ *
+ * @exception IOException If an error occurs.
+ */
public final int read(byte[] b, int off, int len) throws IOException
{
if (off < 0 || len < 0 || off + len > b.length)
return super.read(b, off, len);
}
+ /**
+ * This method reads a Java boolean value from an input stream. It does
+ * so by reading a single byte of data. If that byte is zero, then the
+ * value returned is <code>false</code>. If the byte is non-zero, then
+ * the value returned is <code>true</code>.
+ * <p>
+ * This method can read a <code>boolean</code> written by an object
+ * implementing the <code>writeBoolean()</code> method in the
+ * <code>DataOutput</code> interface.
+ *
+ * @return The <code>boolean</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading
+ * the boolean
+ * @exception IOException If any other error occurs
+ */
public final boolean readBoolean() throws IOException
{
return (readByte() != 0);
}
+ /**
+ * This method reads a Java byte value from an input stream. The value
+ * is in the range of -128 to 127.
+ * <p>
+ * This method can read a <code>byte</code> written by an object
+ * implementing the <code>writeByte()</code> method in the
+ * <code>DataOutput</code> interface.
+ *
+ * @return The <code>byte</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading the byte
+ * @exception IOException If any other error occurs
+ *
+ * @see DataOutput
+ */
public final byte readByte() throws IOException
{
int i = read();
return (byte) i;
}
+ /**
+ * This method reads a Java <code>char</code> value from an input stream.
+ * It operates by reading two bytes from the stream and converting them to
+ * a single 16-bit Java <code>char</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 a <code>char</code> in
+ * the following manner:
+ * <p>
+ * <code>(char)(((byte1 & 0xFF) << 8) | (byte2 & 0xFF)</code>
+ * <p>
+ * This method can read a <code>char</code> written by an object
+ * implementing the <code>writeChar()</code> method in the
+ * <code>DataOutput</code> interface.
+ *
+ * @return The <code>char</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading the char
+ * @exception IOException If any other error occurs
+ *
+ * @see DataOutput
+ */
public final char readChar() throws IOException
{
return (char) ((readByte() << 8) | readUnsignedByte());
}
+ /**
+ * This method reads a Java double value from an input stream. It operates
+ * by first reading a <code>long</code> value from the stream by calling the
+ * <code>readLong()</code> method in this interface, then converts
+ * that <code>long</code> to a <code>double</code> using the
+ * <code>longBitsToDouble</code> method in the class
+ * <code>java.lang.Double</code>
+ * <p>
+ * This method can read a <code>double</code> written by an object
+ * implementing the <code>writeDouble()</code> method in the
+ * <code>DataOutput</code> interface.
+ *
+ * @return The <code>double</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading
+ * the double
+ * @exception IOException If any other error occurs
+ *
+ * @see java.lang.Double
+ * @see DataOutput
+ */
public final double readDouble() throws IOException
{
return Double.longBitsToDouble(readLong());
}
+ /**
+ * This method reads a Java float value from an input stream. It
+ * operates by first reading an <code>int</code> value from the
+ * stream by calling the <code>readInt()</code> method in this
+ * interface, then converts that <code>int</code> to a
+ * <code>float</code> using the <code>intBitsToFloat</code> method
+ * in the class <code>java.lang.Float</code>
+ * <p>
+ * This method can read a <code>float</code> written by an object
+ * implementing the * <code>writeFloat()</code> method in the
+ * <code>DataOutput</code> interface.
+ *
+ * @return The <code>float</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading the float
+ * @exception IOException If any other error occurs
+ *
+ * @see java.lang.Float
+ * @see DataOutput */
public final float readFloat() throws IOException
{
return Float.intBitsToFloat(readInt());
}
+ /**
+ * This method reads raw bytes into the passed array until the array is
+ * full. Note that this method blocks until the data is available and
+ * throws an exception if there is not enough data left in the stream to
+ * fill the buffer
+ *
+ * @param b The buffer into which to read the data
+ *
+ * @exception EOFException If end of file is reached before filling
+ * the buffer
+ * @exception IOException If any other error occurs */
public final void readFully(byte[] b) throws IOException
{
readFully(b, 0, b.length);
}
+ /**
+ * This method reads raw bytes into the passed array
+ * <code>buf</code> starting <code>offset</code> bytes into the
+ * buffer. The number of bytes read will be exactly
+ * <code>len</code> Note that this method blocks until the data is
+ * available and * throws an exception if there is not enough data
+ * left in the stream to read <code>len</code> bytes.
+ *
+ * @param buf The buffer into which to read the data
+ * @param offset The offset into the buffer to start storing data
+ * @param len The number of bytes to read into the buffer
+ *
+ * @exception EOFException If end of file is reached before filling
+ * the buffer
+ * @exception IOException If any other error occurs
+ */
public final void readFully(byte[] b, int off, int len) throws IOException
{
if (off < 0 || len < 0 || off + len > b.length)
}
}
+ /**
+ * This method reads a Java <code>int</code> value from an input
+ * stream It operates by reading four bytes from the stream and
+ * converting them to a single Java <code>int</code> The 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> through <code>byte4</code>
+ * represent the first four bytes read from the stream, they will be
+ * transformed to an <code>int</code> in the following manner:
+ * <p>
+ * <code>(int)(((byte1 & 0xFF) << 24) + ((byte2 & 0xFF) << 16) +
+ * ((byte3 & 0xFF) << 8) + (byte4 & 0xFF)))</code>
+ * <p>
+ * The value returned is in the range of 0 to 65535.
+ * <p>
+ * This method can read an <code>int</code> written by an object
+ * implementing the <code>writeInt()</code> method in the
+ * <code>DataOutput</code> interface.
+ *
+ * @return The <code>int</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading the int
+ * @exception IOException If any other error occurs
+ *
+ * @see DataOutput
+ */
public final int readInt() throws IOException
{
int retval = 0;
return retval;
}
- // Deprecated as of JDK 1.1
+ /**
+ * This method reads the next line of text data from an input
+ * stream. It operates by reading bytes and converting those bytes
+ * to <code>char</code> values by treating the byte read as the low
+ * eight bits of the <code>char</code> and using 0 as the high eight
+ * bits. Because of this, it does not support the full 16-bit
+ * Unicode character set.
+ * <p>
+ * The reading of bytes ends when either the end of file or a line
+ * terminator is encountered. The bytes read are then returned as a
+ * <code>String</code> A line terminator is a byte sequence
+ * consisting of either <code>\r</code>, <code>\n</code> or
+ * <code>\r\n</code>. These termination charaters are discarded and
+ * are not returned as part of the string.
+ * <p>
+ * This method can read data that was written by an object implementing the
+ * <code>writeLine()</code> method in <code>DataOutput</code>.
+ *
+ * @return The line read as a <code>String</code>
+ *
+ * @exception IOException If an error occurs
+ *
+ * @see DataOutput
+ *
+ * @deprecated
+ */
public final String readLine() throws IOException
{
StringBuffer strb = new StringBuffer();
return strb.length() > 0 ? strb.toString() : "";
}
+ /**
+ * This method reads a Java long value from an input stream
+ * It operates by reading eight bytes from the stream and converting them to
+ * a single Java <code>long</code> The 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> through <code>byte8</code>
+ * represent the first eight bytes read from the stream, they will
+ * be transformed to an <code>long</code> in the following manner:
+ * <p>
+ * <code>(long)((((long)byte1 & 0xFF) << 56) + (((long)byte2 & 0xFF) << 48) +
+ * (((long)byte3 & 0xFF) << 40) + (((long)byte4 & 0xFF) << 32) +
+ * (((long)byte5 & 0xFF) << 24) + (((long)byte6 & 0xFF) << 16) +
+ * (((long)byte7 & 0xFF) << 8) + ((long)byte9 & 0xFF)))</code>
+ * <p>
+ * The value returned is in the range of 0 to 65535.
+ * <p>
+ * This method can read an <code>long</code> written by an object
+ * implementing the <code>writeLong()</code> method in the
+ * <code>DataOutput</code> interface.
+ *
+ * @return The <code>long</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading the long
+ * @exception IOException If any other error occurs
+ *
+ * @see DataOutput
+ */
public final long readLong() throws IOException
{
long retval = 0L;
return retval;
}
+ /**
+ * This method reads a signed 16-bit value into a Java in from the
+ * stream. It operates by reading two bytes from the stream and
+ * converting them to a single 16-bit Java <code>short</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 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
+ * <code>DataOutput</code> interface.
+ *
+ * @return The <code>short</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading the value
+ * @exception IOException If any other error occurs
+ *
+ * @see DataOutput
+ */
public final short readShort() throws IOException
{
return (short) ((readByte() << 8) | readUnsignedByte());
}
+ /**
+ * 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 = read();
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
{
return (readUnsignedByte() << 8) | readUnsignedByte();
}
+ /**
+ * 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();
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.
+ * The actual number of bytes skipped is returned. 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 number of bytes actually skipped.
+ *
+ * @exception IOException If an error occurs.
+ */
public final int skipBytes(int n) throws IOException
{
// The contract in the Java Lang. Spec. says that this never
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