Quadcap Embeddable Server

com/quadcap/http/server22/HttpOutputStream.java

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package com.quadcap.http.server22;

/* Copyright 1998 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
 *    Redistributions are made at no charge beyond the reasonable cost of
 *    materials and delivery.
 *
 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
 *    years at the cost of materials and delivery.  Such redistributions
 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
 *
 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
 *
 * Redistributions in binary form must reproduce this Copyright Notice,
 * these license terms, and the disclaimer/limitation of liability set
 * forth as paragraph 6 below, in the documentation and/or other materials
 * provided with the distribution.
 *
 * The Software is provided on an "AS IS" basis.  No warranty is
 * provided that the Software is free of defects, or fit for a
 * particular purpose.  
 *
 * Limitation of Liability. Quadcap Software shall not be liable
 * for any damages suffered by the Licensee or any third party resulting
 * from use of the Software.
 */

import java.io.ByteArrayOutputStream;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import javax.servlet.ServletOutputStream;

import com.quadcap.net.server.WorkerOutputStream;

import com.quadcap.util.Debug;

/**
 * An output stream for writing servlet responses.  This is an
 * abstract class, to be implemented by a network services
 * implementor.  Servlet writers use the output stream to return data
 * to clients.  They access it via the ServletResponse's
 * getOutputStream method, available from within the servlet's service
 * method.  Subclasses of ServletOutputStream must provide an
 * implementation of the write(int) method.
 * <p>
 *
 * This implementation is friendly to servlets which return "small"
 * responses and don't compute Content-Length -- it will compute this
 * header for them automatically.
 *
 * @author Stan Bailes
 */
public class HttpOutputStream extends ServletOutputStream {
    WorkerOutputStream          os;
    HttpResponse                res;
    ByteArrayOutputStream       bos = new ByteArrayOutputStream();
    boolean                     committed       = false;
    boolean                     autoFlush       = true;

    int                         bufferSize      = 32 * 1024;

    /**
     * Construct a new http output stream, attached to the specified
     * worker output stream.
     *
     * @param os the output stream.
     */
    public void reset(WorkerOutputStream os) {
        this.os = os;
        this.bos.reset();
        this.committed = false;
    }

    /**
     * Write a byte to the stream
     *
     * @param b the byte
     */
    public void write(int b) throws IOException {
        if (committed) {
            os.write(b); 
        } else if (bos.size() >= bufferSize) {
            res.writeHeaders();
            bos.writeTo(os);
            committed = true;
            os.write(b);
        } else {
            bos.write(b);
        }
    }

    /**
     * Write a bunch of bytes in one shot.
     *
     * @param buf a buffer where those bytes live
     * @param off the position in the buffer of the first byte to write
     * @param len the number of bytes to write
     *
     * @exception IOException may be thrown
     */
    public void write(byte[] buf, int off, int len) throws IOException {
        if (committed) {
            os.write(buf, off, len);
        } else if (bos.size() + len >= bufferSize) {
            res.writeHeaders();
            bos.writeTo(os);
            committed = true;
            os.write(buf, off, len);
        } else {
            bos.write(buf, off, len);
        }
    }

    /**
     * Flush any buffered output to tht client
     */
    public final void flushBuffered() throws IOException {
        if (!committed) {
            int len = bos.size();
            if (len > 0) {
                res.maybeSetContentLength(len);
            }
            res.writeHeaders();
            bos.writeTo(os);
            committed = true;
        }
        os.flush();
    }

    /**
     * Flush the underlying stream
     */
    public final void flush() throws IOException {
        flushBuffered();
    }

    /**
     * Close does nothing, to prevent clients from closing streams when they
     * really don't want to
     */
    public final void close() throws IOException {
        flushBuffered();
    }

    public final void reallyClose() throws IOException {
        os.close();
    }
        
    /**
     * Discard any bytes written so far if possible, and return true if
     * we were able to do so.
     */
    public boolean discard() {
        if (!committed) {
            bos.reset();
            return true;
        }
        return false;
    }
    
    /**
     * Set up the connection with the http response object so we can
     * control flushing the headers when we've reached our buffered
     * limit.
     *
     * @param res the http response object associated with this request
     */
    void setResponse(HttpResponse res) {
        this.res = res;
    }

    /**
     * Return the underlying output stream
     */
    WorkerOutputStream getOutputStream() { return os; }

    final void setBufferSize(int size) throws IllegalStateException {
        if (committed) {
            throw new IllegalStateException("Response already committed");
        }
        this.bufferSize = size;
    }

    final int getBufferSize() {
        return bufferSize;
    }

    final boolean isCommitted() {
        return committed;
    }

    final void reset() throws IllegalStateException {
        if (committed) {
            throw new IllegalStateException("Response already committed");
        }
        bos.reset();
    }

    final boolean getAutoFlush() {
        return autoFlush;
    }

    final void setAutoFlush(boolean autoFlush) {
        this.autoFlush = autoFlush;
    }

    public int getRemaining() {
        return bufferSize - bos.size();
    }
}