Tomcat example source code file (Msg.java)

This example Tomcat source code file (Msg.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

character, io, ioexception, ioexception, msg, msg, string, string, stringbuffer, stringbuffer

The Tomcat Msg.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.jk.core;

import java.io.IOException;

import org.apache.tomcat.util.buf.ByteChunk;
import org.apache.tomcat.util.buf.MessageBytes;


/**
 * A single packet for communication between the web server and the
 * container.
 *
 * In a more generic sense, it's the event that drives the processing chain.
 * XXX Use Event, make Msg a particular case.
 *
 * @author Henri Gomez [hgomez@apache.org]
 * @author Dan Milstein [danmil@shore.net]
 * @author Keith Wannamaker [Keith@Wannamaker.org]
 * @author Kevin Seguin
 * @author Costin Manolache
 */
public abstract class Msg {

    
    
    /**
     * Prepare this packet for accumulating a message from the container to
     * the web server.  Set the write position to just after the header
     * (but leave the length unwritten, because it is as yet unknown).
     */
    public abstract void reset();

    /**
     * For a packet to be sent to the web server, finish the process of
     * accumulating data and write the length of the data payload into
     * the header.  
     */
    public abstract void end();

    public abstract  void appendInt( int val );

    public abstract void appendByte( int val );
	
    public abstract void appendLongInt( int val );

    /**
     */
    public abstract void appendBytes(MessageBytes mb) throws IOException;

    public abstract void appendByteChunk(ByteChunk bc) throws IOException;
    
    /** 
     * Copy a chunk of bytes into the packet, starting at the current
     * write position.  The chunk of bytes is encoded with the length
     * in two bytes first, then the data itself, and finally a
     * terminating \0 (which is <B>not included in the encoded
     * length).
     *
     * @param b The array from which to copy bytes.
     * @param off The offset into the array at which to start copying
     * @param numBytes The number of bytes to copy.  
     */
    public abstract void appendBytes( byte b[], int off, int numBytes );

    /**
     * Read an integer from packet, and advance the read position past
     * it.  Integers are encoded as two unsigned bytes with the
     * high-order byte first, and, as far as I can tell, in
     * little-endian order within each byte.  
     */
    public abstract int getInt();

    public abstract int peekInt();

    public abstract byte getByte();

    public abstract byte peekByte();

    public abstract void getBytes(MessageBytes mb);
    
    /**
     * Copy a chunk of bytes from the packet into an array and advance
     * the read position past the chunk.  See appendBytes() for details
     * on the encoding.
     *
     * @return The number of bytes copied.
     */
    public abstract int getBytes(byte dest[]);

    /**
     * Read a 32 bits integer from packet, and advance the read position past
     * it.  Integers are encoded as four unsigned bytes with the
     * high-order byte first, and, as far as I can tell, in
     * little-endian order within each byte.
     */
    public abstract int getLongInt();

    public abstract int getHeaderLength();

    public abstract int processHeader();

    public abstract byte[] getBuffer();

    public abstract int getLen();
    
    public abstract void dump(String msg);

    /* -------------------- Utilities -------------------- */
    // XXX Move to util package

    public static String hexLine( byte buf[], int start, int len ) {
        StringBuffer sb=new StringBuffer();
        for( int i=start; i< start+16 ; i++ ) {
            if( i < len + 4)
                sb.append( hex( buf[i] ) + " ");
            else
                sb.append( "   " );
        }
        sb.append(" | ");
        for( int i=start; i < start+16 && i < len + 4; i++ ) {
            if( ! Character.isISOControl( (char)buf[i] ))
                sb.append( new Character((char)buf[i]) );
            else
                sb.append( "." );
        }
        return sb.toString();
    }

    private  static String hex( int x ) {
        //	    if( x < 0) x=256 + x;
        String h=Integer.toHexString( x );
        if( h.length() == 1 ) h = "0" + h;
        return h.substring( h.length() - 2 );
    }


}