/*
*
*
* Copyright 1990-2007 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 only, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License version 2 for more details (a copy is
* included at /legal/license.txt).
*
* You should have received a copy of the GNU General Public License
* version 2 along with this work; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*/
package java.io;
/**
* A data input stream lets an application read primitive Java data
* types from an underlying input stream in a machine-independent
* way. An application uses a data output stream to write data that
* can later be read by a data input stream.
*
* @version 1.31, 12/04/99 (CLDC 1.0, Spring 2000)
* @see java.io.DataOutputStream
* @since JDK1.0
*/
public
class DataInputStream extends InputStream implements DataInput {
/**
* The input stream.
*/
protected InputStream in;
/**
* Creates a <code>DataInputStream</code>
* and saves its argument, the input stream
* <code>in</code>, for later use.
*
* @param in the input stream.
*/
public DataInputStream(InputStream in) {
this.in = in;
}
/**
* Reads the next byte of data from this input stream. The value
* byte is returned as an <code>int</code> in the range
* <code>0</code> to <code>255</code>. If no byte is available
* because the end of the stream has been reached, the value
* <code>-1</code> is returned. This method blocks until input data
* is available, the end of the stream is detected, or an exception
* is thrown.
* <p>
* This method
* simply performs <code>in.read()</code> and returns the result.
*
* @return the next byte of data, or <code>-1</code> if the end of the
* stream is reached.
* @exception IOException if an I/O error occurs.
*/
public int read() throws IOException {
return in.read();
}
/**
* See the general contract of the <code>read</code>
* method of <code>DataInput</code>.
* <p>
* Bytes for this operation are read from the contained
* input stream.
*
* @param b the buffer into which the data is read.
* @return the total number of bytes read into the buffer, or
* <code>-1</code> if there is no more data because the end
* of the stream has been reached.
* @exception IOException if an I/O error occurs.
* @see java.io.InputStream#read(byte[], int, int)
*/
public final int read(byte b[]) throws IOException {
return in.read(b, 0, b.length);
}
/**
* Reads up to <code>len</code> bytes of data from this input stream
* into an array of bytes. This method blocks until some input is
* available.
* <p>
* This method simply performs <code>in.read(b, off, len)</code>
* and returns the result.
*
* @param b the buffer into which the data is read.
* @param off the start offset of the data.
* @param len the maximum number of bytes read.
* @return the total number of bytes read into the buffer, or
* <code>-1</code> if there is no more data because the end of
* the stream has been reached.
* @exception IOException if an I/O error occurs.
*/
public final int read(byte b[], int off, int len) throws IOException {
return in.read(b, off, len);
}
/**
* See the general contract of the <code>readFully</code>
* method of <code>DataInput</code>.
* <p>
* Bytes for this operation are read from the contained
* input stream.
*
* @param b the buffer into which the data is read.
* @exception EOFException if this input stream reaches the end before
* reading all the bytes.
* @exception IOException if an I/O error occurs.
*/
public final void readFully(byte b[]) throws IOException {
readFully(b, 0, b.length);
}
/**
* See the general contract of the <code>readFully</code>
* method of <code>DataInput</code>.
* <p>
* Bytes for this operation are read from the contained
* input stream.
*
* @param b the buffer into which the data is read.
* @param off the start offset of the data.
* @param len the number of bytes to read.
* @exception EOFException if this input stream reaches the end before
* reading all the bytes.
* @exception IOException if an I/O error occurs.
*/
public final void readFully(byte b[], int off, int len) throws IOException {
if (len < 0) {
throw new IndexOutOfBoundsException();
}
int n = 0;
while (n < len) {
int count = read(b, off + n, len - n);
if (count < 0) {
throw new EOFException();
}
n += count;
}
}
/**
* See the general contract of the <code>skipBytes</code>
* method of <code>DataInput</code>.
* <p>
* Bytes for this operation are read from the contained
* input stream.
*
* @param n the number of bytes to be skipped.
* @return the actual number of bytes skipped.
* @exception IOException if an I/O error occurs.
*/
public final int skipBytes(int n) throws IOException {
int total = 0;
int cur = 0;
while ((total<n) && ((cur = (int) skip(n-total)) > 0)) {
total += cur;
}
return total;
}
/**
* See the general contract of the <code>readBoolean</code>
* method of <code>DataInput</code>.
* <p>
* Bytes for this operation are read from the contained
* input stream.
*
* @return the <code>boolean</code> value read.
* @exception EOFException if this input stream has reached the end.
* @exception IOException if an I/O error occurs.
*/
public final boolean readBoolean() throws IOException {
int ch = read();
if (ch < 0) {
throw new EOFException();
}
return (ch != 0);
}
/**
* See the general contract of the <code>readByte</code>
* method of <code>DataInput</code>.
* <p>
* Bytes for this operation are read from the contained
* input stream.
*
* @return the next byte of this input stream as a signed 8-bit
* <code>byte</code>.
* @exception EOFException if this input stream has reached the end.
* @exception IOException if an I/O error occurs.
*/
public final byte readByte() throws IOException {
int ch = read();
if (ch < 0) {
throw new EOFException();
}
return (byte)(ch);
}
/**
* See the general contract of the <code>readUnsignedByte</code>
* method of <code>DataInput</code>.
* <p>
* Bytes for this operation are read from the contained
* input stream.
*
* @return the next byte of this input stream, interpreted as an
* unsigned 8-bit number.
* @exception EOFException if this input stream has reached the end.
* @exception IOException if an I/O error occurs.
*/
public final int readUnsignedByte() throws IOException {
int ch = read();
if (ch < 0) {
throw new EOFException();
}
return ch;
}
/**
* See the general contract of the <code>readShort</code>
* method of <code>DataInput</code>.
* <p>
* Bytes for this operation are read from the contained
* input stream.
*
* @return the next two bytes of this input stream, interpreted as a
* signed 16-bit number.
* @exception EOFException if this input stream reaches the end before
* reading two bytes.
* @exception IOException if an I/O error occurs.
*/
public final short readShort() throws IOException {
return (short)readUnsignedShort();
}
/**
* See the general contract of the <code>readUnsignedShort</code>
* method of <code>DataInput</code>.
* <p>
* Bytes for this operation are read from the contained
* input stream.
*
* @return the next two bytes of this input stream, interpreted as an
* unsigned 16-bit integer.
* @exception EOFException if this input stream reaches the end before
* reading two bytes.
* @exception IOException if an I/O error occurs.
*/
public final int readUnsignedShort() throws IOException {
int ch1 = read();
int ch2 = read();
if ((ch1 | ch2) < 0) {
throw new EOFException();
}
return (ch1 << 8) + (ch2 << 0);
}
/**
* See the general contract of the <code>readChar</code>
* method of <code>DataInput</code>.
* <p>
* Bytes for this operation are read from the contained
* input stream.
*
* @return the next two bytes of this input stream as a Unicode
* character.
* @exception EOFException if this input stream reaches the end before
* reading two bytes.
* @exception IOException if an I/O error occurs.
*/
public final char readChar() throws IOException {
return (char)readUnsignedShort();
}
/**
* See the general contract of the <code>readInt</code>
* method of <code>DataInput</code>.
* <p>
* Bytes for this operation are read from the contained
* input stream.
*
* @return the next four bytes of this input stream, interpreted as an
* <code>int</code>.
* @exception EOFException if this input stream reaches the end before
* reading four bytes.
* @exception IOException if an I/O error occurs.
*/
public final int readInt() throws IOException {
int ch1 = read();
int ch2 = read();
int ch3 = read();
int ch4 = read();
if ((ch1 | ch2 | ch3 | ch4) < 0) {
throw new EOFException();
}
return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));
}
/**
* See the general contract of the <code>readLong</code>
* method of <code>DataInput</code>.
* <p>
* Bytes for this operation are read from the contained
* input stream.
*
* @return the next eight bytes of this input stream, interpreted as a
* <code>long</code>.
* @exception EOFException if this input stream reaches the end before
* reading eight bytes.
* @exception IOException if an I/O error occurs.
*/
public final long readLong() throws IOException {
return ((long)(readInt()) << 32) + (readInt() & 0xFFFFFFFFL);
}
/**
* See the general contract of the <code>readUTF</code>
* method of <code>DataInput</code>.
* <p>
* Bytes for this operation are read from the contained
* input stream.
*
* @return a Unicode string.
* @exception EOFException if this input stream reaches the end before
* reading all the bytes.
* @exception IOException if an I/O error occurs.
* @see java.io.DataInputStream#readUTF(java.io.DataInput)
*/
public final String readUTF() throws IOException {
return readUTF(this);
}
/**
* Reads from the
* stream <code>in</code> a representation
* of a Unicode character string encoded in
* Java modified UTF-8 format; this string
* of characters is then returned as a <code>String</code>.
* The details of the modified UTF-8 representation
* are exactly the same as for the <code>readUTF</code>
* method of <code>DataInput</code>.
*
* @param in a data input stream.
* @return a Unicode string.
* @exception EOFException if the input stream reaches the end
* before all the bytes.
* @exception IOException if an I/O error occurs.
* @exception UTFDataFormatException if the bytes do not represent a
* valid UTF-8 encoding of a Unicode string.
* @see java.io.DataInputStream#readUnsignedShort()
*/
public final static String readUTF(DataInput in) throws IOException {
int utflen = in.readUnsignedShort();
char str[] = new char[utflen];
byte bytearr [] = new byte[utflen];
int c, char2, char3;
int count = 0;
int strlen = 0;
in.readFully(bytearr, 0, utflen);
while (count < utflen) {
c = (int) bytearr[count] & 0xff;
switch (c >> 4) {
case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
/* 0xxxxxxx*/
count++;
str[strlen++] = (char)c;
break;
case 12: case 13:
/* 110x xxxx 10xx xxxx*/
count += 2;
if (count > utflen)
throw new UTFDataFormatException();
char2 = (int) bytearr[count-1];
if ((char2 & 0xC0) != 0x80)
throw new UTFDataFormatException();
str[strlen++] = (char)(((c & 0x1F) << 6) | (char2 & 0x3F));
break;
case 14:
/* 1110 xxxx 10xx xxxx 10xx xxxx */
count += 3;
if (count > utflen)
throw new UTFDataFormatException();
char2 = (int) bytearr[count-2];
char3 = (int) bytearr[count-1];
if (((char2 & 0xC0) != 0x80) || ((char3 & 0xC0) != 0x80))
throw new UTFDataFormatException();
str[strlen++] = (char)(((c & 0x0F) << 12) |
((char2 & 0x3F) << 6) |
((char3 & 0x3F) << 0));
break;
default:
/* 10xx xxxx, 1111 xxxx */
throw new UTFDataFormatException();
}
}
// The number of chars produced may be less than utflen
return new String(str, 0, strlen);
}
/**
* Skips over and discards <code>n</code> bytes of data from the
* input stream. The <code>skip</code> method may, for a variety of
* reasons, end up skipping over some smaller number of bytes,
* possibly <code>0</code>. The actual number of bytes skipped is
* returned.
* <p>
* This method
* simply performs <code>in.skip(n)</code>.
*
* @param n the number of bytes to be skipped.
* @return the actual number of bytes skipped.
* @exception IOException if an I/O error occurs.
*/
public long skip(long n) throws IOException {
return in.skip(n);
}
/**
* Returns the number of bytes that can be read from this input
* stream without blocking.
* <p>
* This method
* simply performs <code>in.available(n)</code> and
* returns the result.
*
* @return the number of bytes that can be read from the input stream
* without blocking.
* @exception IOException if an I/O error occurs.
*/
public int available() throws IOException {
return in.available();
}
/**
* Closes this input stream and releases any system resources
* associated with the stream.
* This
* method simply performs <code>in.close()</code>.
*
* @exception IOException if an I/O error occurs.
*/
public void close() throws IOException {
in.close();
}
/**
* Marks the current position in this input stream. A subsequent
* call to the <code>reset</code> method repositions this stream at
* the last marked position so that subsequent reads re-read the same bytes.
* <p>
* The <code>readlimit</code> argument tells this input stream to
* allow that many bytes to be read before the mark position gets
* invalidated.
* <p>
* This method simply performs <code>in.mark(readlimit)</code>.
*
* @param readlimit the maximum limit of bytes that can be read before
* the mark position becomes invalid.
*/
public synchronized void mark(int readlimit) {
in.mark(readlimit);
}
/**
* Repositions this stream to the position at the time the
* <code>mark</code> method was last called on this input stream.
* <p>
* This method
* simply performs <code>in.reset()</code>.
* <p>
* Stream marks are intended to be used in
* situations where you need to read ahead a little to see what's in
* the stream. Often this is most easily done by invoking some
* general parser. If the stream is of the type handled by the
* parse, it just chugs along happily. If the stream is not of
* that type, the parser should toss an exception when it fails.
* If this happens within readlimit bytes, it allows the outer
* code to reset the stream and try another parser.
*
* @exception IOException if the stream has not been marked or if the
* mark has been invalidated.
*/
public synchronized void reset() throws IOException {
in.reset();
}
/**
* Tests if this input stream supports the <code>mark</code>
* and <code>reset</code> methods.
* This method
* simply performs <code>in.markSupported()</code>.
*
* @return <code>true</code> if this stream type supports the
* <code>mark</code> and <code>reset</code> method;
* <code>false</code> otherwise.
*/
public boolean markSupported() {
return in.markSupported();
}
}
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