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Tomcat example source code file (ByteChunk.java)

This example Tomcat source code file (ByteChunk.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

buffer, bytechunk, bytechunk, byteinputchannel, byteoutputchannel, byteoutputchannel, default_character_encoding, io, ioexception, ioexception, iso-8859-1, serializable, string, string, xxx

The Tomcat ByteChunk.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.tomcat.util.buf;

import java.io.IOException;
import java.io.Serializable;

/*
 * In a server it is very important to be able to operate on
 * the original byte[] without converting everything to chars.
 * Some protocols are ASCII only, and some allow different
 * non-UNICODE encodings. The encoding is not known beforehand,
 * and can even change during the execution of the protocol.
 * ( for example a multipart message may have parts with different
 *  encoding )
 *
 * For HTTP it is not very clear how the encoding of RequestURI
 * and mime values can be determined, but it is a great advantage
 * to be able to parse the request without converting to string.
 */

// TODO: This class could either extend ByteBuffer, or better a ByteBuffer inside
// this way it could provide the search/etc on ByteBuffer, as a helper.

/**
 * This class is used to represent a chunk of bytes, and
 * utilities to manipulate byte[].
 *
 * The buffer can be modified and used for both input and output.
 *
 * There are 2 modes: The chunk can be associated with a sink - ByteInputChannel or ByteOutputChannel,
 * which will be used when the buffer is empty ( on input ) or filled ( on output ).
 * For output, it can also grow. This operating mode is selected by calling setLimit() or
 * allocate(initial, limit) with limit != -1.
 *
 * Various search and append method are defined - similar with String and StringBuffer, but
 * operating on bytes.
 *
 * This is important because it allows processing the http headers directly on the received bytes,
 * without converting to chars and Strings until the strings are needed. In addition, the charset
 * is determined later, from headers or user code.
 *
 *
 * @author dac@sun.com
 * @author James Todd [gonzo@sun.com]
 * @author Costin Manolache
 * @author Remy Maucherat
 */
public final class ByteChunk implements Cloneable, Serializable {

    /** Input interface, used when the buffer is emptiy
     *
     * Same as java.nio.channel.ReadableByteChannel
     */
    public static interface ByteInputChannel {
        /** 
         * Read new bytes ( usually the internal conversion buffer ).
         * The implementation is allowed to ignore the parameters, 
         * and mutate the chunk if it wishes to implement its own buffering.
         */
        public int realReadBytes(byte cbuf[], int off, int len)
            throws IOException;
    }

    /** Same as java.nio.channel.WrittableByteChannel.
     */
    public static interface ByteOutputChannel {
        /** 
         * Send the bytes ( usually the internal conversion buffer ).
         * Expect 8k output if the buffer is full.
         */
        public void realWriteBytes(byte cbuf[], int off, int len)
            throws IOException;
    }

    // --------------------

    /** Default encoding used to convert to strings. It should be UTF8,
	as most standards seem to converge, but the servlet API requires
	8859_1, and this object is used mostly for servlets. 
    */
    public static final String DEFAULT_CHARACTER_ENCODING="ISO-8859-1";
        
    // byte[]
    private byte[] buff;

    private int start=0;
    private int end;

    private String enc;

    private boolean isSet=false; // XXX

    // How much can it grow, when data is added
    private int limit=-1;

    private ByteInputChannel in = null;
    private ByteOutputChannel out = null;

    private boolean isOutput=false;
    private boolean optimizedWrite=true;
    
    /**
     * Creates a new, uninitialized ByteChunk object.
     */
    public ByteChunk() {
    }

    public ByteChunk( int initial ) {
	allocate( initial, -1 );
    }

    //--------------------
    public ByteChunk getClone() {
	try {
	    return (ByteChunk)this.clone();
	} catch( Exception ex) {
	    return null;
	}
    }

    public boolean isNull() {
	return ! isSet; // buff==null;
    }
    
    /**
     * Resets the message buff to an uninitialized state.
     */
    public void recycle() {
	//	buff = null;
	enc=null;
	start=0;
	end=0;
	isSet=false;
    }

    public void reset() {
	buff=null;
    }

    // -------------------- Setup --------------------

    public void allocate( int initial, int limit  ) {
	isOutput=true;
	if( buff==null || buff.length < initial ) {
	    buff=new byte[initial];
	}    
	this.limit=limit;
	start=0;
	end=0;
	isSet=true;
    }

    /**
     * Sets the message bytes to the specified subarray of bytes.
     * 
     * @param b the ascii bytes
     * @param off the start offset of the bytes
     * @param len the length of the bytes
     */
    public void setBytes(byte[] b, int off, int len) {
        buff = b;
        start = off;
        end = start+ len;
        isSet=true;
    }

    public void setOptimizedWrite(boolean optimizedWrite) {
        this.optimizedWrite = optimizedWrite;
    }

    public void setEncoding( String enc ) {
	this.enc=enc;
    }
    public String getEncoding() {
        if (enc == null)
            enc=DEFAULT_CHARACTER_ENCODING;
        return enc;
    }

    /**
     * Returns the message bytes.
     */
    public byte[] getBytes() {
	return getBuffer();
    }

    /**
     * Returns the message bytes.
     */
    public byte[] getBuffer() {
	return buff;
    }

    /**
     * Returns the start offset of the bytes.
     * For output this is the end of the buffer.
     */
    public int getStart() {
	return start;
    }

    public int getOffset() {
	return start;
    }

    public void setOffset(int off) {
        if (end < off ) end=off;
	start=off;
    }

    /**
     * Returns the length of the bytes.
     * XXX need to clean this up
     */
    public int getLength() {
	return end-start;
    }

    /** Maximum amount of data in this buffer.
     *
     *  If -1 or not set, the buffer will grow undefinitely.
     *  Can be smaller than the current buffer size ( which will not shrink ).
     *  When the limit is reached, the buffer will be flushed ( if out is set )
     *  or throw exception.
     */
    public void setLimit(int limit) {
	this.limit=limit;
    }
    
    public int getLimit() {
	return limit;
    }

    /**
     * When the buffer is empty, read the data from the input channel.
     */
    public void setByteInputChannel(ByteInputChannel in) {
        this.in = in;
    }

    /** When the buffer is full, write the data to the output channel.
     * 	Also used when large amount of data is appended.
     *
     *  If not set, the buffer will grow to the limit.
     */
    public void setByteOutputChannel(ByteOutputChannel out) {
	this.out=out;
    }

    public int getEnd() {
	return end;
    }

    public void setEnd( int i ) {
	end=i;
    }

    // -------------------- Adding data to the buffer --------------------
    /** Append a char, by casting it to byte. This IS NOT intended for unicode.
     *
     * @param c
     * @throws IOException
     */
    public void append( char c )
	throws IOException
    {
	append( (byte)c);
    }

    public void append( byte b )
	throws IOException
    {
	makeSpace( 1 );

	// couldn't make space
	if( limit >0 && end >= limit ) {
	    flushBuffer();
	}
	buff[end++]=b;
    }

    public void append( ByteChunk src )
	throws IOException
    {
	append( src.getBytes(), src.getStart(), src.getLength());
    }

    /** Add data to the buffer
     */
    public void append( byte src[], int off, int len )
	throws IOException
    {
	// will grow, up to limit
	makeSpace( len );

	// if we don't have limit: makeSpace can grow as it wants
	if( limit < 0 ) {
	    // assert: makeSpace made enough space
	    System.arraycopy( src, off, buff, end, len );
	    end+=len;
	    return;
	}

        // Optimize on a common case.
        // If the buffer is empty and the source is going to fill up all the
        // space in buffer, may as well write it directly to the output,
        // and avoid an extra copy
        if ( optimizedWrite && len == limit && end == start && out != null ) {
            out.realWriteBytes( src, off, len );
            return;
        }
	// if we have limit and we're below
	if( len <= limit - end ) {
	    // makeSpace will grow the buffer to the limit,
	    // so we have space
	    System.arraycopy( src, off, buff, end, len );
	    end+=len;
	    return;
	}

	// need more space than we can afford, need to flush
	// buffer

	// the buffer is already at ( or bigger than ) limit

        // We chunk the data into slices fitting in the buffer limit, although
        // if the data is written directly if it doesn't fit

        int avail=limit-end;
        System.arraycopy(src, off, buff, end, avail);
        end += avail;

        flushBuffer();

        int remain = len - avail;

        while (remain > (limit - end)) {
            out.realWriteBytes( src, (off + len) - remain, limit - end );
            remain = remain - (limit - end);
        }

        System.arraycopy(src, (off + len) - remain, buff, end, remain);
        end += remain;

    }


    // -------------------- Removing data from the buffer --------------------

    public int substract()
        throws IOException {

        if ((end - start) == 0) {
            if (in == null)
                return -1;
            int n = in.realReadBytes( buff, 0, buff.length );
            if (n < 0)
                return -1;
        }

        return (buff[start++] & 0xFF);

    }

    public int substract(ByteChunk src)
        throws IOException {

        if ((end - start) == 0) {
            if (in == null)
                return -1;
            int n = in.realReadBytes( buff, 0, buff.length );
            if (n < 0)
                return -1;
        }

        int len = getLength();
        src.append(buff, start, len);
        start = end;
        return len;

    }

    public int substract( byte src[], int off, int len )
        throws IOException {

        if ((end - start) == 0) {
            if (in == null)
                return -1;
            int n = in.realReadBytes( buff, 0, buff.length );
            if (n < 0)
                return -1;
        }

        int n = len;
        if (len > getLength()) {
            n = getLength();
        }
        System.arraycopy(buff, start, src, off, n);
        start += n;
        return n;

    }


    /** Send the buffer to the sink. Called by append() when the limit is reached.
     *  You can also call it explicitely to force the data to be written.
     *
     * @throws IOException
     */
    public void flushBuffer()
	throws IOException
    {
	//assert out!=null
	if( out==null ) {
	    throw new IOException( "Buffer overflow, no sink " + limit + " " +
				   buff.length  );
	}
	out.realWriteBytes( buff, start, end-start );
	end=start;
    }

    /** Make space for len chars. If len is small, allocate
     *	a reserve space too. Never grow bigger than limit.
     */
    private void makeSpace(int count)
    {
	byte[] tmp = null;

	int newSize;
	int desiredSize=end + count;

	// Can't grow above the limit
	if( limit > 0 &&
	    desiredSize > limit) {
	    desiredSize=limit;
	}

	if( buff==null ) {
	    if( desiredSize < 256 ) desiredSize=256; // take a minimum
	    buff=new byte[desiredSize];
	}
	
	// limit < buf.length ( the buffer is already big )
	// or we already have space XXX
	if( desiredSize <= buff.length ) {
	    return;
	}
	// grow in larger chunks
	if( desiredSize < 2 * buff.length ) {
	    newSize= buff.length * 2;
	    if( limit >0 &&
		newSize > limit ) newSize=limit;
	    tmp=new byte[newSize];
	} else {
	    newSize= buff.length * 2 + count ;
	    if( limit > 0 &&
		newSize > limit ) newSize=limit;
	    tmp=new byte[newSize];
	}
	
	System.arraycopy(buff, start, tmp, 0, end-start);
	buff = tmp;
	tmp = null;
	end=end-start;
	start=0;
    }
    
    // -------------------- Conversion and getters --------------------

    public String toString() {
        if (null == buff) {
            return null;
        } else if (end-start == 0) {
            return "";
        }
        return StringCache.toString(this);
    }
    
    public String toStringInternal() {
        String strValue=null;
        try {
            if( enc==null ) enc=DEFAULT_CHARACTER_ENCODING;
            strValue = new String( buff, start, end-start, enc );
            /*
             Does not improve the speed too much on most systems,
             it's safer to use the "clasical" new String().
             
             Most overhead is in creating char[] and copying,
             the internal implementation of new String() is very close to
             what we do. The decoder is nice for large buffers and if
             we don't go to String ( so we can take advantage of reduced GC)
             
             // Method is commented out, in:
              return B2CConverter.decodeString( enc );
              */
        } catch (java.io.UnsupportedEncodingException e) {
            // Use the platform encoding in that case; the usage of a bad
            // encoding will have been logged elsewhere already
            strValue = new String(buff, start, end-start);
        }
        return strValue;
    }

    public int getInt()
    {
	return Ascii.parseInt(buff, start,end-start);
    }

    public long getLong() {
        return Ascii.parseLong(buff, start,end-start);
    }


    // -------------------- equals --------------------

    /**
     * Compares the message bytes to the specified String object.
     * @param s the String to compare
     * @return true if the comparison succeeded, false otherwise
     */
    public boolean equals(String s) {
	// XXX ENCODING - this only works if encoding is UTF8-compat
	// ( ok for tomcat, where we compare ascii - header names, etc )!!!
	
	byte[] b = buff;
	int blen = end-start;
	if (b == null || blen != s.length()) {
	    return false;
	}
	int boff = start;
	for (int i = 0; i < blen; i++) {
	    if (b[boff++] != s.charAt(i)) {
		return false;
	    }
	}
	return true;
    }

    /**
     * Compares the message bytes to the specified String object.
     * @param s the String to compare
     * @return true if the comparison succeeded, false otherwise
     */
    public boolean equalsIgnoreCase(String s) {
	byte[] b = buff;
	int blen = end-start;
	if (b == null || blen != s.length()) {
	    return false;
	}
	int boff = start;
	for (int i = 0; i < blen; i++) {
	    if (Ascii.toLower(b[boff++]) != Ascii.toLower(s.charAt(i))) {
		return false;
	    }
	}
	return true;
    }

    public boolean equals( ByteChunk bb ) {
	return equals( bb.getBytes(), bb.getStart(), bb.getLength());
    }
    
    public boolean equals( byte b2[], int off2, int len2) {
	byte b1[]=buff;
	if( b1==null && b2==null ) return true;

	int len=end-start;
	if ( len2 != len || b1==null || b2==null ) 
	    return false;
		
	int off1 = start;

	while ( len-- > 0) {
	    if (b1[off1++] != b2[off2++]) {
		return false;
	    }
	}
	return true;
    }

    public boolean equals( CharChunk cc ) {
	return equals( cc.getChars(), cc.getStart(), cc.getLength());
    }
    
    public boolean equals( char c2[], int off2, int len2) {
	// XXX works only for enc compatible with ASCII/UTF !!!
	byte b1[]=buff;
	if( c2==null && b1==null ) return true;
	
	if (b1== null || c2==null || end-start != len2 ) {
	    return false;
	}
	int off1 = start;
	int len=end-start;
	
	while ( len-- > 0) {
	    if ( (char)b1[off1++] != c2[off2++]) {
		return false;
	    }
	}
	return true;
    }

    /**
     * Returns true if the message bytes starts with the specified string.
     * @param s the string
     */
    public boolean startsWith(String s) {
	// Works only if enc==UTF
	byte[] b = buff;
	int blen = s.length();
	if (b == null || blen > end-start) {
	    return false;
	}
	int boff = start;
	for (int i = 0; i < blen; i++) {
	    if (b[boff++] != s.charAt(i)) {
		return false;
	    }
	}
	return true;
    }

    /* Returns true if the message bytes start with the specified byte array */
    public boolean startsWith(byte[] b2) {
        byte[] b1 = buff;
        if (b1 == null && b2 == null) {
            return true;
        }

        int len = end - start;
        if (b1 == null || b2 == null || b2.length > len) {
            return false;
        }
        for (int i = start, j = 0; i < end && j < b2.length; ) {
            if (b1[i++] != b2[j++]) 
                return false;
        }
        return true;
    }

    /**
     * Returns true if the message bytes starts with the specified string.
     * @param s the string
     * @param pos The position
     */
    public boolean startsWithIgnoreCase(String s, int pos) {
	byte[] b = buff;
	int len = s.length();
	if (b == null || len+pos > end-start) {
	    return false;
	}
	int off = start+pos;
	for (int i = 0; i < len; i++) {
	    if (Ascii.toLower( b[off++] ) != Ascii.toLower( s.charAt(i))) {
		return false;
	    }
	}
	return true;
    }

    public int indexOf( String src, int srcOff, int srcLen, int myOff ) {
	char first=src.charAt( srcOff );

	// Look for first char 
	int srcEnd = srcOff + srcLen;
        
	for( int i=myOff+start; i <= (end - srcLen); i++ ) {
	    if( buff[i] != first ) continue;
	    // found first char, now look for a match
            int myPos=i+1;
	    for( int srcPos=srcOff + 1; srcPos< srcEnd; ) {
                if( buff[myPos++] != src.charAt( srcPos++ ))
		    break;
                if( srcPos==srcEnd ) return i-start; // found it
	    }
	}
	return -1;
    }

    // -------------------- Hash code  --------------------

    // normal hash. 
    public int hash() {
	return hashBytes( buff, start, end-start);
    }

    // hash ignoring case
    public int hashIgnoreCase() {
	return hashBytesIC( buff, start, end-start );
    }

    private static int hashBytes( byte buff[], int start, int bytesLen ) {
	int max=start+bytesLen;
	byte bb[]=buff;
	int code=0;
	for (int i = start; i < max ; i++) {
	    code = code * 37 + bb[i];
	}
	return code;
    }

    private static int hashBytesIC( byte bytes[], int start,
				    int bytesLen )
    {
	int max=start+bytesLen;
	byte bb[]=bytes;
	int code=0;
	for (int i = start; i < max ; i++) {
	    code = code * 37 + Ascii.toLower(bb[i]);
	}
	return code;
    }

    /**
     * Returns true if the message bytes starts with the specified string.
     * @param c the character
     * @param starting The start position
     */
    public int indexOf(char c, int starting) {
	int ret = indexOf( buff, start+starting, end, c);
	return (ret >= start) ? ret - start : -1;
    }

    public static int  indexOf( byte bytes[], int off, int end, char qq )
    {
	// Works only for UTF 
	while( off < end ) {
	    byte b=bytes[off];
	    if( b==qq )
		return off;
	    off++;
	}
	return -1;
    }

    /** Find a character, no side effects.
     *  @return index of char if found, -1 if not
     */
    public static int findChar( byte buf[], int start, int end, char c ) {
	byte b=(byte)c;
	int offset = start;
	while (offset < end) {
	    if (buf[offset] == b) {
		return offset;
	    }
	    offset++;
	}
	return -1;
    }

    /** Find a character, no side effects.
     *  @return index of char if found, -1 if not
     */
    public static int findChars( byte buf[], int start, int end, byte c[] ) {
	int clen=c.length;
	int offset = start;
	while (offset < end) {
	    for( int i=0; i<clen; i++ ) 
		if (buf[offset] == c[i]) {
		    return offset;
		}
	    offset++;
	}
	return -1;
    }

    /** Find the first character != c 
     *  @return index of char if found, -1 if not
     */
    public static int findNotChars( byte buf[], int start, int end, byte c[] )
    {
	int clen=c.length;
	int offset = start;
	boolean found;
		
	while (offset < end) {
	    found=true;
	    for( int i=0; i<clen; i++ ) {
		if (buf[offset] == c[i]) {
		    found=false;
		    break;
		}
	    }
	    if( found ) { // buf[offset] != c[0..len]
		return offset;
	    }
	    offset++;
	}
	return -1;
    }


    /**
     * Convert specified String to a byte array. This ONLY WORKS for ascii, UTF chars will be truncated.
     * 
     * @param value to convert to byte array
     * @return the byte array value
     */
    public static final byte[] convertToBytes(String value) {
        byte[] result = new byte[value.length()];
        for (int i = 0; i < value.length(); i++) {
            result[i] = (byte) value.charAt(i);
        }
        return result;
    }
    
    
}

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