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Tomcat example source code file (CharChunk.java)

This example Tomcat source code file (CharChunk.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, charchunk, charchunk, charinputchannel, charoutputchannel, charsequence, clonenotsupportedexception, io, ioexception, ioexception, serializable, string, string, xxx, xxx

The Tomcat CharChunk.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;

/**
 * Utilities to manipluate char chunks. While String is
 * the easiest way to manipulate chars ( search, substrings, etc),
 * it is known to not be the most efficient solution - Strings are
 * designed as imutable and secure objects.
 * 
 * @author dac@sun.com
 * @author James Todd [gonzo@sun.com]
 * @author Costin Manolache
 * @author Remy Maucherat
 */
public final class CharChunk implements Cloneable, Serializable, CharSequence {

    // Input interface, used when the buffer is emptied.
    public static interface CharInputChannel {
        /** 
         * 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 realReadChars(char cbuf[], int off, int len)
            throws IOException;
    }
    /**
     *  When we need more space we'll either
     *  grow the buffer ( up to the limit ) or send it to a channel.
     */
    public static interface CharOutputChannel {
	/** Send the bytes ( usually the internal conversion buffer ).
	 *  Expect 8k output if the buffer is full.
	 */
        public void realWriteChars(char cbuf[], int off, int len)
            throws IOException;
    }
    
    // -------------------- 
    // char[]
    private char buff[];

    private int start;
    private int end;

    private boolean isSet=false;  // XXX 

    private boolean isOutput=false;

    // -1: grow undefinitely
    // maximum amount to be cached
    private int limit=-1;

    private CharInputChannel in = null;
    private CharOutputChannel out = null;
    
    private boolean optimizedWrite=true;

    /**
     * Creates a new, uninitialized CharChunk object.
     */
    public CharChunk() {
    }

    public CharChunk(int size) {
	allocate( size, -1 );
    }

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

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

    public void reset() {
	buff=null;
    }

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

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


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

    public void setChars( char[] c, int off, int len ) {
        buff=c;
        start=off;
        end=start + len;
        isSet=true;
    }

    /** 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 setCharInputChannel(CharInputChannel 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 setCharOutputChannel(CharOutputChannel out) {
	this.out=out;
    }

    // compat 
    public char[] getChars()
    {
	return getBuffer();
    }
    
    public char[] 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;
    }

    /**
     * Returns the start offset of the bytes.
     */
    public void setOffset(int off) {
	start=off;
    }

    /**
     * Returns the length of the bytes.
     */
    public int getLength() {
	return end-start;
    }


    public int getEnd() {
	return end;
    }

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

    // -------------------- Adding data --------------------
    
    public void append( char b )
	throws IOException
    {
	makeSpace( 1 );

	// couldn't make space
	if( limit >0 && end >= limit ) {
	    flushBuffer();
	}
	buff[end++]=b;
    }
    
    public void append( CharChunk src )
	throws IOException
    {
	append( src.getBuffer(), src.getOffset(), src.getLength());
    }

    /** Add data to the buffer
     */
    public void append( char 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 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.realWriteChars( 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
	
	// Optimization:
	// If len-avail < length ( i.e. after we fill the buffer with
	// what we can, the remaining will fit in the buffer ) we'll just
	// copy the first part, flush, then copy the second part - 1 write
	// and still have some space for more. We'll still have 2 writes, but
	// we write more on the first.

	if( len + end < 2 * limit ) {
	    /* If the request length exceeds the size of the output buffer,
	       flush the output buffer and then write the data directly.
	       We can't avoid 2 writes, but we can write more on the second
	    */
	    int avail=limit-end;
	    System.arraycopy(src, off, buff, end, avail);
	    end += avail;
	    
	    flushBuffer();
	    
	    System.arraycopy(src, off+avail, buff, end, len - avail);
	    end+= len - avail;
	    
	} else {	// len > buf.length + avail
	    // long write - flush the buffer and write the rest
	    // directly from source
	    flushBuffer();
	    
	    out.realWriteChars( src, off, len );
	}
    }


    /** Add data to the buffer
     */
    public void append( StringBuffer sb )
	throws IOException
    {
	int len=sb.length();

	// 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
	    sb.getChars(0, len, buff, end );
	    end+=len;
	    return;
	}

	int off=0;
	int sbOff = off;
	int sbEnd = off + len;
	while (sbOff < sbEnd) {
	    int d = min(limit - end, sbEnd - sbOff);
	    sb.getChars( sbOff, sbOff+d, buff, end);
	    sbOff += d;
	    end += d;
	    if (end >= limit)
		flushBuffer();
	}
    }

    /** Append a string to the buffer
     */
    public void append(String s) throws IOException {
        append(s, 0, s.length());
    }
    
    /** Append a string to the buffer
     */
    public void append(String s, int off, int len) throws IOException {
	if (s==null) return;
	
	// 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
	    s.getChars(off, off+len, buff, end );
	    end+=len;
	    return;
	}

	int sOff = off;
	int sEnd = off + len;
	while (sOff < sEnd) {
	    int d = min(limit - end, sEnd - sOff);
	    s.getChars( sOff, sOff+d, buff, end);
	    sOff += d;
	    end += d;
	    if (end >= limit)
		flushBuffer();
	}
    }
    
    // -------------------- Removing data from the buffer --------------------

    public int substract()
        throws IOException {

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

        return (buff[start++]);

    }

    public int substract(CharChunk src)
        throws IOException {

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

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

    }

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

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

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

    }


    public void flushBuffer()
	throws IOException
    {
	//assert out!=null
	if( out==null ) {
	    throw new IOException( "Buffer overflow, no sink " + limit + " " +
				   buff.length  );
	}
	out.realWriteChars( 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)
    {
	char[] 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 char[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 char[newSize];
	} else {
	    newSize= buff.length * 2 + count ;
	    if( limit > 0 &&
		newSize > limit ) newSize=limit;
	    tmp=new char[newSize];
	}
	
	System.arraycopy(buff, start, tmp, start, end-start);
	buff = tmp;
	tmp = null;
    }
    
    // -------------------- Conversion and getters --------------------

    public String toString() {
        if (null == buff) {
            return null;
        } else if (end-start == 0) {
            return "";
        }
        return StringCache.toString(this);
    }
    
    public String toStringInternal() {
        return new String(buff, start, end-start);
    }

    public int getInt()
    {
	return Ascii.parseInt(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) {
	char[] c = buff;
	int len = end-start;
	if (c == null || len != s.length()) {
	    return false;
	}
	int off = start;
	for (int i = 0; i < len; i++) {
	    if (c[off++] != 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) {
	char[] c = buff;
	int len = end-start;
	if (c == null || len != s.length()) {
	    return false;
	}
	int off = start;
	for (int i = 0; i < len; i++) {
	    if (Ascii.toLower( c[off++] ) != Ascii.toLower( s.charAt(i))) {
		return false;
	    }
	}
	return true;
    }

    public boolean equals(CharChunk cc) {
	return equals( cc.getChars(), cc.getOffset(), cc.getLength());
    }

    public boolean equals(char b2[], int off2, int len2) {
	char b1[]=buff;
	if( b1==null && b2==null ) return true;
	
	if (b1== null || b2==null || end-start != len2) {
	    return false;
	}
	int off1 = start;
	int len=end-start;
	while ( len-- > 0) {
	    if (b1[off1++] != b2[off2++]) {
		return false;
	    }
	}
	return true;
    }

    public boolean equals(byte b2[], int off2, int len2) {
	char b1[]=buff;
	if( b2==null && b1==null ) return true;

	if (b1== null || b2==null || end-start != len2) {
	    return false;
	}
	int off1 = start;
	int len=end-start;
	
	while ( len-- > 0) {
	    if ( b1[off1++] != (char)b2[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) {
	char[] c = buff;
	int len = s.length();
	if (c == null || len > end-start) {
	    return false;
	}
	int off = start;
	for (int i = 0; i < len; i++) {
	    if (c[off++] != s.charAt(i)) {
		return false;
	    }
	}
	return true;
    }
    
    /**
     * Returns true if the message bytes starts with the specified string.
     * @param s the string
     */
    public boolean startsWithIgnoreCase(String s, int pos) {
	char[] c = buff;
	int len = s.length();
	if (c == null || len+pos > end-start) {
	    return false;
	}
	int off = start+pos;
	for (int i = 0; i < len; i++) {
	    if (Ascii.toLower( c[off++] ) != Ascii.toLower( s.charAt(i))) {
		return false;
	    }
	}
	return true;
    }
    

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

    // normal hash. 
    public int hash() {
	int code=0;
	for (int i = start; i < start + end-start; i++) {
	    code = code * 37 + buff[i];
	}
	return code;
    }

    // hash ignoring case
    public int hashIgnoreCase() {
	int code=0;
	for (int i = start; i < end; i++) {
	    code = code * 37 + Ascii.toLower(buff[i]);
	}
	return code;
    }

    public int indexOf(char c) {
	return indexOf( c, start);
    }
    
    /**
     * Returns true if the message bytes starts with the specified string.
     * @param c the character
     */
    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( char chars[], int off, int cend, char qq )
    {
	while( off < cend ) {
	    char b=chars[off];
	    if( b==qq )
		return off;
	    off++;
	}
	return -1;
    }
    

    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;
    }

    // -------------------- utils
    private int min(int a, int b) {
	if (a < b) return a;
	return b;
    }

    // Char sequence impl
    
    public char charAt(int index) {
        return buff[index + start];
    }
    
    public CharSequence subSequence(int start, int end) {
        try {
            CharChunk result = (CharChunk) this.clone();
            result.setOffset(this.start + start);
            result.setEnd(this.start + end);
            return result;
        } catch (CloneNotSupportedException e) {
            // Cannot happen
            return null;
        }
    }
    
    public int length() {
        return end - start;
    }
    
}

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