filterrouter.java

ajax patterns 这是关于ajax设计模式方面的原代码

/*
    Copyright 2006 Christian Gross http://www.devspace.com
    From the book Ajax Patterns and Best Practices

   Licensed 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 devspace.ajax.statenavigation;
import java.util.*;
import java.util.regex.*;
import javax.servlet.http.*;
import java.io.*;
import javax.servlet.*;


class CompareMimeTypes implements Comparator {
    
    public CompareMimeTypes() {
    }
    private String[] SplitBuffer( String item) {
        StringTokenizer tokenizer = new StringTokenizer( item, ";");
        String acceptType = null;
        if( tokenizer.hasMoreTokens()) {
            acceptType = (String)tokenizer.nextToken();
        }
        if( tokenizer.hasMoreTokens()) {
            return new String[] { acceptType, (String)tokenizer.nextToken()};
        }
        else {
            return new String[] { acceptType};
    }
        
    }
    private class PriorityValue {
        public int level;
        public double value;
    }
    
    public PriorityValue CalculateValue(String val) {
        PriorityValue value = new PriorityValue();
        String[] buffers = SplitBuffer( val);
        double multiplier = 1.0;
        if (buffers.length > 1) {
            multiplier = new Double( buffers[1].substring(2)).doubleValue();
        }
        value.value = multiplier;
        value.level = 0;
        if ( buffers[ 0].compareTo( "*/*") == 0) {
            value.level = 1;
        }
        else if (buffers[ 0].indexOf( "/*") != -1) {
            value.level = 2;
        }
        else if ( buffers[ 0].compareTo( "application/xhtml+xml") == 0) {
            value.level = 4;
        }
        else {
            value.level = 3;
        }
        return value;
    }
    
    public int compare(Object x, Object y) {
        int levelx = 0, levely = 0;
        double qvaluex = 0.0, qvaluey = 0.0;
        PriorityValue valX = CalculateValue((String)x);
        PriorityValue valY = CalculateValue((String)y);
        levelx = valX.level;
        levely = valY.level;
        qvaluex = valX.value;
        qvaluey = valY.value;
        if (levelx < levely) {
            return 1;
        }
        else if (levelx > levely) {
            return -1;
        }
        else {
            if (qvaluex < qvaluey) {
                return 1;
            }
            else if (qvaluex > qvaluey) {
                return -1;
            }
            else {
                return 0;
            }
        }
    }
}

public class FilterRouter implements Router {
    //Rewriter _defaultRewriter;
    FilterConfig _configuration;
    String _baseDirectory;
    
    public FilterRouter() {
        
    }
    /*
    public FilterRouter( String baseDirectory, Rewriter rewriter) throws Exception {
        if (rewriter == null) {
            throw new Exception( "Rewriter cannot be null");
        }
        _defaultRewriter = rewriter;
        _baseDirectory = baseDirectory;
    }*/
    public void setConfiguration( FilterConfig config) {
        _configuration = config;
        _baseDirectory = config.getInitParameter("base-directory");
    }
    public boolean IsResource(HttpServletRequest request) {
        String path = _baseDirectory + request.getRequestURI();
        if( new File( path).exists()) {
            return false;
        }
        else {
            return true;
        }
    }
    private ArrayList parseHeaders( String header) {
        ArrayList arr = new ArrayList();
        StringTokenizer tokenizer = new StringTokenizer( header, ",");
        while( tokenizer.hasMoreTokens()) {
            arr.add((String)tokenizer.nextToken());
        }
        
        String[] strArray = new String[ arr.size()];
        for( int i = 0; i < arr.size(); i ++) {
            strArray[ i] = (String)arr.get( i);
        }
        Arrays.sort( strArray, new CompareMimeTypes());
        return arr;
    }
    public void WriteRedirection(Rewriter rewriter, HttpServletRequest request) {
        ArrayList elements = parseHeaders( request.getHeader( "Accept"));
        Iterator iter = elements.iterator();
        while( iter.hasNext()) {
            StringTokenizer tokenizer = new StringTokenizer((String)iter.next(), ";");
            if( rewriter.WriteRedirection( tokenizer.nextToken())) {
                break;
            }
        }
    }
}