URLEncoder.java

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 * Copyright 2004 The Apache Software Foundation
 *
 * 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
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package org.apache.catalina.util;

import org.apache.catalina.core.StandardServer;
import org.glassfish.logging.annotation.LogMessageInfo;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.util.BitSet;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 *
 * This class is very similar to the java.net.URLEncoder class.
 *
 * Unfortunately, with java.net.URLEncoder there is no way to specify to the 
 * java.net.URLEncoder which characters should NOT be encoded.
 *
 * This code was moved from DefaultServlet.java
 *
 * @author Craig R. McClanahan
 * @author Remy Maucherat
 */
public class URLEncoder {

    private static final Logger log = StandardServer.log;

    @LogMessageInfo(
            message = "UTF8 not supported",
            level = "WARNING"
    )
    public static final String UTF8_NOT_SUPPORTED_EXCEPTION = "AS-WEB-CORE-00490";

    static final char[] hexadecimal =
    {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
     'A', 'B', 'C', 'D', 'E', 'F'};

    //Array containing the safe characters set.
    protected BitSet safeCharacters = new BitSet(256);

    public URLEncoder() {
        for (char i = 'a'; i <= 'z'; i++) {
            addSafeCharacter(i);
        }
        for (char i = 'A'; i <= 'Z'; i++) {
            addSafeCharacter(i);
        }
        for (char i = '0'; i <= '9'; i++) {
            addSafeCharacter(i);
        }
    }

    public void addSafeCharacter( char c ) {
	safeCharacters.set( c );
    }

    public String encode( String path ) {
        int maxBytesPerChar = 10;
        int caseDiff = ('a' - 'A');
        StringBuilder rewrittenPath = new StringBuilder(path.length());
        ByteArrayOutputStream buf = new ByteArrayOutputStream(maxBytesPerChar);
        OutputStreamWriter writer = null;
        try {
            writer = new OutputStreamWriter(buf, "UTF8");
        } catch (UnsupportedEncodingException e) {
            log.log(Level.WARNING, UTF8_NOT_SUPPORTED_EXCEPTION, e);
            writer = new OutputStreamWriter(buf);
        }

        for (int i = 0; i < path.length(); i++) {
            int c = (int) path.charAt(i);
            if (safeCharacters.get(c)) {
                rewrittenPath.append((char)c);
            } else {
                // convert to external encoding before hex conversion
                try {
                    writer.write(c);
                    writer.flush();
                } catch(IOException e) {
                    buf.reset();
                    continue;
                }
                byte[] ba = buf.toByteArray();
                for (int j = 0; j < ba.length; j++) {
                    // Converting each byte in the buffer
                    byte toEncode = ba[j];
                    rewrittenPath.append('%');
                    int low = (int) (toEncode & 0x0f);
                    int high = (int) ((toEncode & 0xf0) >> 4);
                    rewrittenPath.append(hexadecimal[high]);
                    rewrittenPath.append(hexadecimal[low]);
                }
                buf.reset();
            }
        }
        return rewrittenPath.toString();
    }
}