urlencoder.java

一个日本流行的,功能较全的开源Web办公管理(Groupware)系统。

package jp.co.sjts.gsession.tools;


import java.io.ByteArrayOutputStream;
import java.io.OutputStreamWriter;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.BitSet;

/**
 * <p>MIME宍幃(www-form-url 晞崋壔)僋儔僗  URLEncoder.java
 * Copyright (C) 1999-2000 Japan Total System Co,LTD
 *
 * @author   Satoru K   &lt;[e-mail]&gt;
 */
public class URLEncoder {
	static BitSet dontNeedEncoding;
	static final int caseDiff = ('a' - 'A');

	static {
		dontNeedEncoding = new BitSet(256);
		int i;
		for (i = 'a'; i <= 'z'; i++) {
			dontNeedEncoding.set(i);
		}
		for (i = 'A'; i <= 'Z'; i++) {
			dontNeedEncoding.set(i);
		}
		for (i = '0'; i <= '9'; i++) {
			dontNeedEncoding.set(i);
		}
		dontNeedEncoding.set(' '); 
		dontNeedEncoding.set('-');
		dontNeedEncoding.set('_');
		dontNeedEncoding.set('.');
		dontNeedEncoding.set('*');
	}

	private URLEncoder() { }


	public static String encode(String s,String enc) throws UnsupportedEncodingException{
		int maxBytesPerChar = 10;
		StringBuffer out = new StringBuffer(s.length());
		ByteArrayOutputStream buf = new ByteArrayOutputStream(maxBytesPerChar);
		OutputStreamWriter writer = new OutputStreamWriter(buf,enc);

		for (int i = 0; i < s.length(); i++) {
			int c = (int)s.charAt(i);
			if (dontNeedEncoding.get(c)) {
				if (c == ' ') {
					c = '+';
				}
				out.append((char)c);
			} else {

				try {
					writer.write(c);
					writer.flush();
				} catch(IOException e) {
					buf.reset();
					continue;
				}
				byte[] ba = buf.toByteArray();
				for (int j = 0; j < ba.length; j++) {
					out.append('%');
					char ch = Character.forDigit((ba[j] >> 4) & 0xF, 16);

					if (Character.isLetter(ch)) {
						ch -= caseDiff;
					}
					out.append(ch);
					ch = Character.forDigit(ba[j] & 0xF, 16);
					if (Character.isLetter(ch)) {
						ch -= caseDiff;
					}
					out.append(ch);
				}
				buf.reset();
			}
		}

		return out.toString();
    }
}