splitservletoutputstream.java

来自「oscache-2.4.1-full」· Java 代码 · 共 95 行

/*
 * Copyright (c) 2002-2003 by OpenSymphony
 * All rights reserved.
 */
package com.opensymphony.oscache.web.filter;

import java.io.IOException;
import java.io.OutputStream;

import javax.servlet.ServletOutputStream;

/**
 * Extends the base <code>ServletOutputStream</code> class so that
 * the stream can be captured as it gets written. This is achieved
 * by overriding the <code>write()</code> methods and outputting
 * the data to two streams - the original stream and a secondary stream
 * that is designed to capture the written data.
 *
 * @version $Revision: 393 $
 * @author  <a href="mailto:[e-mail]">Serge Knystautas</a>
 */
public class SplitServletOutputStream extends ServletOutputStream {
    OutputStream captureStream = null;
    OutputStream passThroughStream = null;

    /**
     * Constructs a split output stream that both captures and passes through
     * the servlet response.
     *
     * @param captureStream The stream that will be used to capture the data.
     * @param passThroughStream The pass-through <code>ServletOutputStream</code>
     * that will write the response to the client as originally intended.
     */
    public SplitServletOutputStream(OutputStream captureStream, OutputStream passThroughStream) {
        this.captureStream = captureStream;
        this.passThroughStream = passThroughStream;
    }

    /**
     * Writes the incoming data to both the output streams.
     *
     * @param value The int data to write.
     * @throws IOException
     */
    public void write(int value) throws IOException {
        captureStream.write(value);
        passThroughStream.write(value);
    }

    /**
     * Writes the incoming data to both the output streams.
     *
     * @param value The bytes to write to the streams.
     * @throws IOException
     */
    public void write(byte[] value) throws IOException {
        captureStream.write(value);
        passThroughStream.write(value);
    }

    /**
     * Writes the incoming data to both the output streams.
     *
     * @param b The bytes to write out to the streams.
     * @param off The offset into the byte data where writing should begin.
     * @param len The number of bytes to write.
     * @throws IOException
     */
    public void write(byte[] b, int off, int len) throws IOException {
        captureStream.write(b, off, len);
        passThroughStream.write(b, off, len);
    }

    /** 
     * Flushes both the output streams.
     * @throws IOException
     */    
    public void flush() throws IOException {
        super.flush();
        captureStream.flush(); //why not?
        passThroughStream.flush();
    }    

    /**
     * Closes both the output streams.
     * @throws IOException 
     */    
    public void close() throws IOException {
        super.close();
        captureStream.close();
        passThroughStream.close();
    }    

}