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StringBufferInputStream.java
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1998-09-22
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/*
* @(#)StringBufferInputStream.java 1.17 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.io;
/**
* This class allows an application to create an input stream in
* which the bytes read are supplied by the contents of a string.
* Applications can also read bytes from a byte array by using a
* <code>ByteArrayInputStream</code>.
* <p>
* Only the low eight bits of each character in the string are used by
* this class.
*
* @author Arthur van Hoff
* @version 1.17, 07/01/98
* @see java.io.ByteArrayInputStream
* @see java.io.StringReader
* @since JDK1.0
* @deprecated This class does not properly convert characters into bytes. As
* of JDK 1.1, the preferred way to create a stream from a
* string is via the <code>StringReader</code> class.
*/
public
class StringBufferInputStream extends InputStream {
/**
* The string from which bytes are read.
*
* @since JDK1.0
*/
protected String buffer;
/**
* The index of the next character to read from the input stream buffer.
*
* @see java.io.StringBufferInputStream#buffer
* @since JDK1.0
*/
protected int pos;
/**
* The number of valid characters in the input stream buffer.
*
* @see java.io.StringBufferInputStream#buffer
* @since JDK1.0
*/
protected int count;
/**
* Creates a string input stream to read data from the specified string.
*
* @param s the underlying input buffer.
* @since JDK1.0
*/
public StringBufferInputStream(String s) {
this.buffer = s;
count = s.length();
}
/**
* 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.
* <p>
* The <code>read</code> method of
* <code>StringBufferInputStream</code> cannot block. It returns the
* low eight bits of the next character in this input stream's buffer.
*
* @return the next byte of data, or <code>-1</code> if the end of the
* stream is reached.
* @since JDK1.0
*/
public synchronized int read() {
return (pos < count) ? (buffer.charAt(pos++) & 0xFF) : -1;
}
/**
* Reads up to <code>len</code> bytes of data from this input stream
* into an array of bytes.
* <p>
* The <code>read</code> method of
* <code>StringBufferInputStream</code> cannot block. It copies the
* low eight bits from the characters in this input stream's buffer into
* the byte array argument.
*
* @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.
* @since JDK1.0
*/
public synchronized int read(byte b[], int off, int len) {
if (pos >= count) {
return -1;
}
if (pos + len > count) {
len = count - pos;
}
if (len <= 0) {
return 0;
}
String s = buffer;
int cnt = len;
while (--cnt >= 0) {
b[off++] = (byte)s.charAt(pos++);
}
return len;
}
/**
* Skips <code>n</code> bytes of input from this input stream. Fewer
* bytes might be skipped if the end of the input stream is reached.
*
* @param n the number of bytes to be skipped.
* @return the actual number of bytes skipped.
* @since JDK1.0
*/
public synchronized long skip(long n) {
if (n < 0) {
return 0;
}
if (n > count - pos) {
n = count - pos;
}
pos += n;
return n;
}
/**
* Returns the number of bytes that can be read from the input
* stream without blocking.
*
* @return the value of <code>count - pos</code>, which is the
* number of bytes remaining to be read from the input buffer.
* @since JDK1.0
*/
public synchronized int available() {
return count - pos;
}
/**
* Resets the input stream to begin reading from the first character
* of this input stream's underlying buffer.
*
* @since JDK1.0
*/
public synchronized void reset() {
pos = 0;
}
}