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SocketInputStream.java
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1998-09-22
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/*
* @(#)SocketInputStream.java 1.16 98/07/01
*
* Copyright 1995-1998 by Sun Microsystems, Inc.,
* 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
* All rights reserved.
*
* This software is the confidential and proprietary information
* of Sun Microsystems, Inc. ("Confidential Information"). You
* shall not disclose such Confidential Information and shall use
* it only in accordance with the terms of the license agreement
* you entered into with Sun.
*/
package java.net;
import java.io.IOException;
import java.io.FileInputStream;
/**
* This stream extends FileInputStream to implement a
* SocketInputStream. Note that this class should <b>NOT</b> be
* public.
*
* @version 1.16, 07/01/98
* @author Jonathan Payne
* @author Arthur van Hoff
*/
class SocketInputStream extends FileInputStream
{
private boolean eof;
private SocketImpl impl;
private byte temp[] = new byte[1];
/**
* Creates a new SocketInputStream. Can only be called
* by a Socket. This method needs to hang on to the owner Socket so
* that the fd will not be closed.
* @param impl the implemented socket input stream
*/
SocketInputStream(SocketImpl impl) throws IOException {
super(impl.getFileDescriptor());
this.impl = impl;
}
/**
* Reads into an array of bytes at the specified offset using
* the received socket primitive.
* @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 actual number of bytes read, -1 is
* returned when the end of the stream is reached.
* @exception IOException If an I/O error has occurred.
*/
private native int socketRead(byte b[], int off, int len)
throws IOException;
/**
* Reads into a byte array data from the socket.
* @param b the buffer into which the data is read
* @return the actual number of bytes read, -1 is
* returned when the end of the stream is reached.
* @exception IOException If an I/O error has occurred.
*/
public int read(byte b[]) throws IOException {
return read(b, 0, b.length);
}
/**
* Reads into a byte array <i>b</i> at offset <i>off</i>,
* <i>length</i> bytes of data.
* @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 actual number of bytes read, -1 is
* returned when the end of the stream is reached.
* @exception IOException If an I/O error has occurred.
*/
public int read(byte b[], int off, int length) throws IOException {
if (eof) {
return -1;
}
int n = socketRead(b, off, length);
if (n <= 0) {
eof = true;
return -1;
}
return n;
}
/**
* Reads a single byte from the socket.
*/
public int read() throws IOException {
if (eof) {
return -1;
}
int n = read(temp, 0, 1);
if (n <= 0) {
return -1;
}
return temp[0] & 0xff;
}
/**
* Skips n bytes of input.
* @param n the number of bytes to skip
* @return the actual number of bytes skipped.
* @exception IOException If an I/O error has occurred.
*/
public long skip(long numbytes) throws IOException {
if (numbytes <= 0) {
return 0;
}
long n = numbytes;
int buflen = (int) Math.min(1024, n);
byte data[] = new byte[buflen];
while (n > 0) {
int r = read(data, 0, (int) Math.min((long) buflen, n));
if (r < 0) {
break;
}
n -= r;
}
return numbytes - n;
}
/**
* Returns the number of bytes that can be read without blocking.
* @return the number of immediately available bytes
*/
public int available() throws IOException {
return impl.available();
}
/**
* Closes the stream.
*/
public void close() throws IOException {
impl.close();
}
/**
* Overrides finalize, the fd is closed by the Socket.
*/
protected void finalize() {}
}