URL符号化パーセンテージ符号化URLDecoder.decodeの大まかな実現原理

package com.dt.test;

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;

/***
 * URL  URLDecoder.decode 
 */
class testURLEncode {
	public void testURLEncode() {
		String testString;
		try {
			testString = URLEncoder.encode(" ", "utf-8");
			System.out.println("testString :　" + testString);
			testString = testString.replace("%", "");
			int length = testString.length() / 2;
			byte[] data = new byte[length];
			for (int i = 0; i < length; i++) {
				data[i] = (byte) Integer.parseInt(testString.substring(2 * i,
						2 * i + 2), 16);
			}
			String result = new String(data, "utf-8");
			System.out.println("result : " + result);
		} catch (UnsupportedEncodingException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
	}
	public void testURLEncodeGBK() {
		String testString;
		String testString0;
		
		try {
			testString = URLEncoder.encode(" ", "utf-8");
			testString0 = testString;
			System.out.println("testString :　" + testString);
			
			testString =  URLDecoder.decode(testString0,"GBK");
			System.out.println("decode : " + testString);
			
			testString =  URLDecoder.decode(testString0,"utf-8");
			System.out.println("decode : " + testString);
			testString =  URLEncoder.encode(" ", "GBK");
			System.out.println("decode : " + testString);
			testString =  URLDecoder.decode(testString,"GBK");
			System.out.println("decode : " + testString);
		} catch (UnsupportedEncodingException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
	}

	public static void main(String[] args) {

		new testURLEncode().testURLEncode();
		new testURLEncode().testURLEncodeGBK();
	}
}

testString :　%E4%B8%AD%E6%96%87
result :  
testString :　%E4%B8%AD%E6%96%87
decode :   
decode :  
decode : %D6%D0%CE%C4
decode :