Tomcat example source code file (OutputBuffer.java)

This example Tomcat source code file (OutputBuffer.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Tomcat tags/keywords

bytechunk, bytechunk, c2bconverter, c2bconverter, clientabortexception, default_encoding, hashmap, io, ioexception, ioexception, object, outputbuffer, outputbuffer, response, security, string, util

The Tomcat OutputBuffer.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */ 

package org.apache.catalina.connector;


import java.io.IOException;
import java.io.Writer;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.HashMap;

import org.apache.coyote.ActionCode;
import org.apache.coyote.Response;
import org.apache.catalina.Globals;
import org.apache.tomcat.util.buf.ByteChunk;
import org.apache.tomcat.util.buf.C2BConverter;


/**
 * The buffer used by Tomcat response. This is a derivative of the Tomcat 3.3
 * OutputBuffer, with the removal of some of the state handling (which in 
 * Coyote is mostly the Processor's responsability).
 *
 * @author Costin Manolache
 * @author Remy Maucherat
 */
public class OutputBuffer extends Writer
    implements ByteChunk.ByteOutputChannel {


    // -------------------------------------------------------------- Constants


    public static final String DEFAULT_ENCODING = 
        org.apache.coyote.Constants.DEFAULT_CHARACTER_ENCODING;
    public static final int DEFAULT_BUFFER_SIZE = 8*1024;


    // ----------------------------------------------------- Instance Variables


    /**
     * The byte buffer.
     */
    private ByteChunk bb;


    /**
     * State of the output buffer.
     */
    private boolean initial = true;


    /**
     * Number of bytes written.
     */
    private long bytesWritten = 0;


    /**
     * Number of chars written.
     */
    private long charsWritten = 0;


    /**
     * Flag which indicates if the output buffer is closed.
     */
    private boolean closed = false;


    /**
     * Do a flush on the next operation.
     */
    private boolean doFlush = false;


    /**
     * Byte chunk used to output bytes.
     */
    private ByteChunk outputChunk = new ByteChunk();


    /**
     * Encoding to use.
     */
    private String enc;


    /**
     * Encoder is set.
     */
    private boolean gotEnc = false;


    /**
     * List of encoders.
     */
    protected HashMap encoders = new HashMap();


    /**
     * Current char to byte converter.
     */
    protected C2BConverter conv;


    /**
     * Associated Coyote response.
     */
    private Response coyoteResponse;


    /**
     * Suspended flag. All output bytes will be swallowed if this is true.
     */
    private boolean suspended = false;


    // ----------------------------------------------------------- Constructors


    /**
     * Default constructor. Allocate the buffer with the default buffer size.
     */
    public OutputBuffer() {

        this(DEFAULT_BUFFER_SIZE);

    }


    /**
     * Alternate constructor which allows specifying the initial buffer size.
     * 
     * @param size Buffer size to use
     */
    public OutputBuffer(int size) {

        bb = new ByteChunk(size);
        bb.setLimit(size);
        bb.setByteOutputChannel(this);

    }


    // ------------------------------------------------------------- Properties


    /**
     * Associated Coyote response.
     * 
     * @param coyoteResponse Associated Coyote response
     */
    public void setResponse(Response coyoteResponse) {
	this.coyoteResponse = coyoteResponse;
    }


    /**
     * Get associated Coyote response.
     * 
     * @return the associated Coyote response
     */
    public Response getResponse() {
        return this.coyoteResponse;
    }


    /**
     * Is the response output suspended ?
     * 
     * @return suspended flag value
     */
    public boolean isSuspended() {
        return this.suspended;
    }


    /**
     * Set the suspended flag.
     * 
     * @param suspended New suspended flag value
     */
    public void setSuspended(boolean suspended) {
        this.suspended = suspended;
    }


    /**
     * Is the response output closed ?
     * 
     * @return closed flag value
     */
    public boolean isClosed() {
        return this.closed;
    }


    // --------------------------------------------------------- Public Methods


    /**
     * Recycle the output buffer.
     */
    public void recycle() {
        
        initial = true;
        bytesWritten = 0;
        charsWritten = 0;
        
        bb.recycle(); 
        closed = false;
        suspended = false;
        
        if (conv!= null) {
            conv.recycle();
        }
        
        gotEnc = false;
        enc = null;
        
    }


    /**
     * Clear cached encoders (to save memory for Comet requests).
     */
    public void clearEncoders() {
        encoders.clear();
    }
    
    
    /**
     * Close the output buffer. This tries to calculate the response size if 
     * the response has not been committed yet.
     * 
     * @throws IOException An underlying IOException occurred
     */
    public void close()
        throws IOException {

        if (closed)
            return;
        if (suspended)
            return;

        if ((!coyoteResponse.isCommitted()) 
            && (coyoteResponse.getContentLengthLong() == -1)) {
            // If this didn't cause a commit of the response, the final content
            // length can be calculated
            if (!coyoteResponse.isCommitted()) {
                coyoteResponse.setContentLength(bb.getLength());
            }
        }

        doFlush(false);
        closed = true;

        coyoteResponse.finish();

    }


    /**
     * Flush bytes or chars contained in the buffer.
     * 
     * @throws IOException An underlying IOException occurred
     */
    public void flush()
        throws IOException {
        doFlush(true);
    }


    /**
     * Flush bytes or chars contained in the buffer.
     * 
     * @throws IOException An underlying IOException occurred
     */
    protected void doFlush(boolean realFlush)
        throws IOException {

        if (suspended)
            return;

        doFlush = true;
        if (initial) {
            coyoteResponse.sendHeaders();
            initial = false;
        }
        if (bb.getLength() > 0) {
            bb.flushBuffer();
        }
        doFlush = false;

        if (realFlush) {
            coyoteResponse.action(ActionCode.ACTION_CLIENT_FLUSH, 
                                  coyoteResponse);
            // If some exception occurred earlier, or if some IOE occurred
            // here, notify the servlet with an IOE
            if (coyoteResponse.isExceptionPresent()) {
                throw new ClientAbortException
                    (coyoteResponse.getErrorException());
            }
        }

    }


    // ------------------------------------------------- Bytes Handling Methods


    /** 
     * Sends the buffer data to the client output, checking the
     * state of Response and calling the right interceptors.
     * 
     * @param buf Byte buffer to be written to the response
     * @param off Offset
     * @param cnt Length
     * 
     * @throws IOException An underlying IOException occurred
     */
    public void realWriteBytes(byte buf[], int off, int cnt)
	throws IOException {

        if (closed)
            return;
        if (coyoteResponse == null)
            return;

        // If we really have something to write
        if (cnt > 0) {
            // real write to the adapter
            outputChunk.setBytes(buf, off, cnt);
            try {
                coyoteResponse.doWrite(outputChunk);
            } catch (IOException e) {
                // An IOException on a write is almost always due to
                // the remote client aborting the request.  Wrap this
                // so that it can be handled better by the error dispatcher.
                throw new ClientAbortException(e);
            }
        }

    }


    public void write(byte b[], int off, int len) throws IOException {

        if (suspended)
            return;

        writeBytes(b, off, len);

    }


    private void writeBytes(byte b[], int off, int len) 
        throws IOException {

        if (closed)
            return;

        bb.append(b, off, len);
        bytesWritten += len;

        // if called from within flush(), then immediately flush
        // remaining bytes
        if (doFlush) {
            bb.flushBuffer();
        }

    }


    public void writeByte(int b)
        throws IOException {

        if (suspended)
            return;

        bb.append((byte) b);
        bytesWritten++;

    }


    // ------------------------------------------------- Chars Handling Methods


    public void write(int c)
        throws IOException {

        if (suspended)
            return;

        conv.convert((char) c);
        conv.flushBuffer();
        charsWritten++;
        
    }


    public void write(char c[])
        throws IOException {

        if (suspended)
            return;

        write(c, 0, c.length);

    }


    public void write(char c[], int off, int len)
        throws IOException {

        if (suspended)
            return;

        conv.convert(c, off, len);
        conv.flushBuffer();
        charsWritten += len;

    }


    /**
     * Append a string to the buffer
     */
    public void write(String s, int off, int len)
        throws IOException {

        if (suspended)
            return;

        charsWritten += len;
        if (s == null)
            s = "null";
        conv.convert(s, off, len);
        conv.flushBuffer();

    }


    public void write(String s)
        throws IOException {

        if (suspended)
            return;

        if (s == null)
            s = "null";
        conv.convert(s);
        conv.flushBuffer();

    } 


    public void setEncoding(String s) {
        enc = s;
    }


    public void checkConverter() 
        throws IOException {

        if (!gotEnc)
            setConverter();

    }


    protected void setConverter() 
        throws IOException {

        if (coyoteResponse != null)
            enc = coyoteResponse.getCharacterEncoding();

        gotEnc = true;
        if (enc == null)
            enc = DEFAULT_ENCODING;
        conv = (C2BConverter) encoders.get(enc);
        if (conv == null) {
            
            if (Globals.IS_SECURITY_ENABLED){
                try{
                    conv = (C2BConverter)AccessController.doPrivileged(
                            new PrivilegedExceptionAction(){

                                public Object run() throws IOException{
                                    return new C2BConverter(bb, enc);
                                }

                            }
                    );              
                }catch(PrivilegedActionException ex){
                    Exception e = ex.getException();
                    if (e instanceof IOException)
                        throw (IOException)e; 
                }
            } else {
                conv = new C2BConverter(bb, enc);
            }
            
            encoders.put(enc, conv);

        }
    }

    
    // --------------------  BufferedOutputStream compatibility


    /**
     * Real write - this buffer will be sent to the client
     */
    public void flushBytes()
        throws IOException {

        bb.flushBuffer();

    }

    public int getBytesWritten() {
        if (bytesWritten < Integer.MAX_VALUE) {
            return (int) bytesWritten;
        }
        return -1;
    }

    public int getCharsWritten() {
        if (charsWritten < Integer.MAX_VALUE) {
            return (int) charsWritten;
        }
        return -1;
    }

    public int getContentWritten() {
        long size = bytesWritten + charsWritten ;
        if (size < Integer.MAX_VALUE) {
            return (int) size;
        }
        return -1;
    }

    public long getContentWrittenLong() {
        return bytesWritten + charsWritten;
    }
    
    /** 
     * True if this buffer hasn't been used ( since recycle() ) -
     * i.e. no chars or bytes have been added to the buffer.  
     */
    public boolean isNew() {
        return (bytesWritten == 0) && (charsWritten == 0);
    }


    public void setBufferSize(int size) {
        if (size > bb.getLimit()) {// ??????
            bb.setLimit(size);
        }
    }


    public void reset() {

        bb.recycle();
        bytesWritten = 0;
        charsWritten = 0;
        gotEnc = false;
        enc = null;
        initial = true;
        
    }


    public int getBufferSize() {
        return bb.getLimit();
    }


}