com.baomidou.framework.upload.multipart.BufferedServletInputStream Maven / Gradle / Ivy
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// Copyright (C) 1999-2001 by Jason Hunter .
// All rights reserved. Use of this class is limited.
// Please see the LICENSE for more information.
package com.baomidou.framework.upload.multipart;
import java.io.IOException;
import javax.servlet.ServletInputStream;
/**
* A BufferedServletInputStream wraps a
* ServletInputStream in order to provide input buffering and to
* avoid calling the the readLine method of the wrapped
* ServletInputStream.
*
* This is necessary because some servlet containers rely on the default
* implementation of the readLine method provided by the Servlet
* API classes, which is very slow. Tomcat 3.2, Tomcat 3.1, the JSWDK 1.0 web
* server and the JSDK2.1 web server are all known to need this class for
* performance reasons.
*
* Also, it may be used to work around a bug in the Servlet API 2.0
* implementation of readLine which contains a bug that causes
* ArrayIndexOutOfBoundsExceptions under certain conditions. Apache
* JServ is known to suffer from this bug.
*
* @author Geoff Soutter
* @version 1.1, 2001/05/21, removed block of commented out code
* @version 1.0, 2000/10/27, initial revision
*/
public class BufferedServletInputStream extends ServletInputStream {
/** input stream we are filtering */
private ServletInputStream in;
/** our buffer */
private byte[] buf = new byte[64 * 1024]; // 64k
/** number of bytes we've read into the buffer */
private int count;
/** current position in the buffer */
private int pos;
/**
* Creates a BufferedServletInputStream that wraps the provided
* ServletInputStream.
*
* @param in
* a servlet input stream.
*/
public BufferedServletInputStream(ServletInputStream in) {
this.in = in;
}
/**
* Fill up our buffer from the underlying input stream. Users of this method
* must ensure that they use all characters in the buffer before calling
* this method.
*
* @exception IOException
* if an I/O error occurs.
*/
private void fill() throws IOException {
int i = in.read(buf, 0, buf.length);
if (i > 0) {
pos = 0;
count = i;
}
}
/**
* Implement buffering on top of the readLine method of the
* wrapped ServletInputStream.
*
* @param b
* an array of bytes into which data is read.
* @param off
* an integer specifying the character at which this method
* begins reading.
* @param len
* an integer specifying the maximum number of bytes to read.
* @return an integer specifying the actual number of bytes read, or -1 if
* the end of the stream is reached.
* @exception IOException
* if an I/O error occurs.
*/
public int readLine(byte b[], int off, int len) throws IOException {
int total = 0;
if (len == 0) {
return 0;
}
int avail = count - pos;
if (avail <= 0) {
fill();
avail = count - pos;
if (avail <= 0) {
return -1;
}
}
int copy = Math.min(len, avail);
int eol = findeol(buf, pos, copy);
if (eol != -1) {
copy = eol;
}
System.arraycopy(buf, pos, b, off, copy);
pos += copy;
total += copy;
while (total < len && eol == -1) {
fill();
avail = count - pos;
if (avail <= 0) {
return total;
}
copy = Math.min(len - total, avail);
eol = findeol(buf, pos, copy);
if (eol != -1) {
copy = eol;
}
System.arraycopy(buf, pos, b, off + total, copy);
pos += copy;
total += copy;
}
return total;
}
/**
* Attempt to find the '\n' end of line marker as defined in the comment of
* the readLine method of ServletInputStream.
*
* @param b
* byte array to search.
* @param pos
* position in byte array to search from.
* @param len
* maximum number of bytes to search.
*
* @return the number of bytes including the \n, or -1 if none found.
*/
private static int findeol(byte b[], int pos, int len) {
int end = pos + len;
int i = pos;
while (i < end) {
if (b[i++] == '\n') {
return i - pos;
}
}
return -1;
}
/**
* Implement buffering on top of the read method of the wrapped
* ServletInputStream.
*
* @return the next byte of data, or -1 if the end of the
* stream is reached.
* @exception IOException
* if an I/O error occurs.
*/
public int read() throws IOException {
if (count <= pos) {
fill();
if (count <= pos) {
return -1;
}
}
return buf[pos++] & 0xff;
}
/**
* Implement buffering on top of the read method of the wrapped
* ServletInputStream.
*
* @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
* -1 if there is no more data because the end of the
* stream has been reached.
* @exception IOException
* if an I/O error occurs.
*/
public int read(byte b[], int off, int len) throws IOException {
int total = 0;
while (total < len) {
int avail = count - pos;
if (avail <= 0) {
fill();
avail = count - pos;
if (avail <= 0) {
if (total > 0)
return total;
else
return -1;
}
}
int copy = Math.min(len - total, avail);
System.arraycopy(buf, pos, b, off + total, copy);
pos += copy;
total += copy;
}
return total;
}
}