因为在做链接来源统计的时候需要把 http://www.baidu.com/baidu?word=%D6%D0%B9%FA%B4%F3%B0%D9%BF%C6%D4%DA%CF%DF%C8%AB%CE%C4%BC%EC%CB%F7&tn=myie2dg 这类的URL编码还原成明文字串，一般大部分的网站都是用普通的URL编码形式，如上面链接中的badu，这种很容易转换和还原，Java包里提供了两个类的不同方法URLEncode.encode()和URLDecode.decode()可以很方便实现，但也有特别一点的就是Google了，http://www.google.com/search?hl=zh-CN&newwindow=1&q=%E4%B8%AD%E5%9B%BD%E5%A4%A7%E7%99%BE%E7%A7%91%E5%9C%A8%E7%BA%BF%E5%85%A8%E6%96%87%E6%A3%80%E7%B4%A2&btnG=%E6%90%9C%E7%B4%A2&lr= 他们的编码和别人不一样，如果使用URLDecode.decode()的话则变成乱码，查询的一些相关资料都说Google使用的是UTF-8编码，这点我就有些奇怪了，如果Google使用的是UTF-8编码，那别人使用的又是什么？IE的高级选项里不是有项“始终以UTF-8形式发送URL”的吗？但是UTF-8一个中文是3byte，而一般的编码则是2个byte,这就是为什么一般的URL中是以两组'%'代码表示一个汉字，如“中”的URL编码为"%D6%D0"，而UTF-8则为3组，“中”为"%E4%B8%AD"，这个问题我在Google里也没得到较好回答。我对各种编码形式了解的不是很好，之前只看过如何将字符串转成Utf8-URL编码的方法，其实也挺简单的，直接转成byte后直接取其16进制值前面加个%就行，还原方法在网上搜了几圈居然没发现有现成的！倒是也是几个人在CSDN问了此类的问题。最后还是决定自己搞定了，基本上是toUTF8的原路退回法，再加了个检测URL链接是否UTF-8形式的方法，觉得已经蛮好用了。可以拿出来 share一下。

import java.io.UnsupportedEncodingException;
            import java.net.URLEncoder;
            import java.net.URLDecoder;
            /**
            * <p>Title:字符编码工具类 </p>
            * <p>Deion:  </p>
            * <p>Copyright: flashman.com.cn Copyright (c) 2005</p>
            * <p>Company: flashman.com.cn </p>
            * @author: jeffzhu
            * @version 1.0
            */
            public class CharTools {
            /**
            * 转换编码 ISO-8859-1到GB2312
            * @param text
            * @return
            */
            public String ISO2GB(String text) {
            String result = "";
            try {
            result = new String(text.getBytes("ISO-8859-1"), "GB2312");
            }
            catch (UnsupportedEncodingException ex) {
            result = ex.toString();
            }
            return result;
            }
            /**
            * 转换编码 GB2312到ISO-8859-1
            * @param text
            * @return
            */
            public String GB2ISO(String text) {
            String result = "";
            try {
            result = new String(text.getBytes("GB2312"), "ISO-8859-1");
            }
            catch (UnsupportedEncodingException ex) {
            ex.printStackTrace();
            }
            return result;
            }
            /**
            * Utf8URL编码
            * @param s
            * @return
            */
            public String Utf8URLencode(String text) {
            StringBuffer result = new StringBuffer();
            for (int i = 0; i < text.length(); i++) {
            char c = text.charAt(i);
            if (c >= 0 && c <= 255) {
            result.append(c);
            }else {
            byte[] b = new byte[0];
            try {
            b = Character.toString(c).getBytes("UTF-8");
            }catch (Exception ex) {
            }
            for (int j = 0; j < b.length; j++) {
            int k = b[j];
            if (k < 0) k += 256;
            result.append("%" + Integer.toHexString(k).toUpperCase());
            }
            }
            }
            return result.toString();
            }
            /**
            * Utf8URL解码
            * @param text
            * @return
            */
            public String Utf8URLdecode(String text) {
            String result = "";
            int p = 0;
            if (text!=null && text.length()>0){
            text = text.toLowerCase();
            p = text.indexOf("%e");
            if (p == -1) return text;
            while (p != -1) {
            result += text.substring(0, p);
            text = text.substring(p, text.length());
            if (text == "" || text.length() < 9) return result;
            result += CodeToWord(text.substring(0, 9));
            text = text.substring(9, text.length());
            p = text.indexOf("%e");
            }
            }
            return result + text;
            }
            /**
            * utf8URL编码转字符
            * @param text
            * @return
            */
            private String CodeToWord(String text) {
            String result;
            if (Utf8codeCheck(text)) {
            byte[] code = new byte[3];
            code[0] = (byte) (Integer.parseInt(text.substring(1, 3), 16) - 256);
            code[1] = (byte) (Integer.parseInt(text.substring(4, 6), 16) - 256);
            code[2] = (byte) (Integer.parseInt(text.substring(7, 9), 16) - 256);
            try {
            result = new String(code, "UTF-8");
            }catch (UnsupportedEncodingException ex) {
            result = null;
            }
            }
            else {
            result = text;
            }
            return result;
            }
            /**
            * 编码是否有效
            * @param text
            * @return
            */
            private boolean Utf8codeCheck(String text){
            String sign = "";
            if (text.startsWith("%e"))
            for (int i = 0, p = 0; p != -1; i++) {
            p = text.indexOf("%", p);
            if (p != -1)
            p++;
            sign += p;
            }
            return sign.equals("147-1");
            }
            /**
            * 是否Utf8Url编码
            * @param text
            * @return
            */
            public boolean isUtf8Url(String text) {
            text = text.toLowerCase();
            int p = text.indexOf("%");
            if (p != -1 && text.length() - p > 9) {
            text = text.substring(p, p + 9);
            }
            return Utf8codeCheck(text);
            }
            /**
            * 测试
            * @param args
            */
            public static void main(String[] args) {
            CharTools charTools = new CharTools();
            String url;
            url = "http://www.google.com/search?hl=zh-CN&newwindow=1&q=%E4%B8%AD%E5%9B%BD%E5%A4%A7%E7%99%BE%E7%A7%91%E5%9C%A8%E7%BA%BF%E5%85%A8%E6%96%87%E6%A3%80%E7%B4%A2&btnG=%E6%90%9C%E7%B4%A2&lr=";
            if(charTools.isUtf8Url(url)){
            System.out.println(charTools.Utf8URLdecode(url));
            }else{
            System.out.println(URLDecoder.decode(url));
            }
            url = "http://www.baidu.com/baidu?word=%D6%D0%B9%FA%B4%F3%B0%D9%BF%C6%D4%DA%CF%DF%C8%AB%CE%C4%BC%EC%CB%F7&tn=myie2dg";
            if(charTools.isUtf8Url(url)){
            System.out.println(charTools.Utf8URLdecode(url));
            }else{
            System.out.println(URLDecoder.decode(url));
            }
            }
            }