网上也有一些代码，大部分都是通过输入的关键字来识别编码，并解码。但是搜索引擎得到的referer来源地址上的关键字是通过URLencode编码过的，而且各个网站的关键字Urlencode编码都不一样，gbk,utf-8,gb2312等等。 所以必须要通过编码后的关键字，例如“解析关键字编码”在google里面输入搜索，得到编码后的“%E8%A7%A3%E6%9E%90%E5%85%B3%E9%94%AE%E5%AD%97%E7%BC%96%E7%A0%81” 链接地址为http://www.google.cn/search?q=%E8%A7%A3%E6%9E%90%E5%85%B3%E9%94%AE%E5%AD%97%E7%BC%96%E7%A0%81
1.从以上地址中解析出关键字部分。
2.通过编码后的关键字获取编码时的编码名称（如：gbk,utf-8等等）
3.用URLdecode(keywords,encodeCode)来解码得到对应的关键字。以下是java代码的实现：

package test;

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class ParseURLKeyword {
public static void main(String[] args) {
        String url = "http://www.google.co.kr/search?hl=en&q=%ED%95%9C%EA%B5%AD%EC%96%B4+&btnG=Google+Search&aq=f&oq=";
        System.out.println(ParseURLKeyword.getKeyword(url));
        System.out.println("");
        url = "http://www.google.cn/search?q=%E6%8F%90%E5%8F%96+%E6%90%9C%E7%B4%A2%E5%BC%95%E6%93%8E+%E5%85%B3%E9%94%AE%E5%AD%97&hl=zh-CN&newwindow=1&sa=2";
        System.out.println(ParseURLKeyword.getKeyword(url));
        System.out.println("");
        url = "http://www.google.com.tw/search?hl=zh-CN&q=%E6%B9%98%E9%8B%BC%E4%B8%AD%E5%9C%8B%E9%A6%99%E7%85%99&btnG=Google+%E6%90%9C%E7%B4%A2&aq=f&oq=";
        System.out.println(ParseURLKeyword.getKeyword(url));
        System.out.println("");
        url = "http://www.baidu.com/s?wd=%D6%D0%87%F8%D3%D0%BE%80%D8%9F%C8%CE%B9%AB%CB%BE";
        System.out.println(ParseURLKeyword.getKeyword(url));
        System.out.println("");
        url = "http://www.baidu.com/s?wd=%C6%F3%D2%B5%CD%C6%B9%E3";
        System.out.println(ParseURLKeyword.getKeyword(url));
        System.out.println("");
    }

public static String getKeyword(String url){
        String keywordReg = "(?:yahoo.+?[\\?|&]p=|openfind.+?query=|google.+?q=|lycos.+?query=|onseek.+?keyword=|search\\.tom.+?word=|search\\.qq\\.com.+?word=|zhongsou\\.com.+?word=|search\\.msn\\.com.+?q=|yisou\\.com.+?p=|sina.+?word=|sina.+?query=|sina.+?_searchkey=|sohu.+?word=|sohu.+?key_word=|sohu.+?query=|163.+?q=|baidu.+?wd=|soso.+?w=|3721\\.com.+?p=|Alltheweb.+?q=)([^&]*)";
        String encodeReg = "^(?:[\\x00-\\x7f]|[\\xfc-\\xff][\\x80-\\xbf]{5}|[\\xf8-\\xfb][\\x80-\\xbf]{4}|[\\xf0-\\xf7][\\x80-\\xbf]{3}|[\\xe0-\\xef][\\x80-\\xbf]{2}|[\\xc0-\\xdf][\\x80-\\xbf])+$";

        Pattern keywordPatt = Pattern.compile(keywordReg);
        StringBuffer keyword = new StringBuffer(20);
        Matcher keywordMat = keywordPatt.matcher(url);
while (keywordMat.find()) {
            keywordMat.appendReplacement(keyword, "$1");
        }
if (!keyword.toString().equals("")){
            String keywordsTmp = keyword.toString().replace("http://www.", "");
            Pattern encodePatt = Pattern.compile(encodeReg);
            String unescapeString = ParseURLKeyword.unescape(keywordsTmp);
            Matcher encodeMat = encodePatt.matcher(unescapeString);
            String encodeString = "gbk";
if (encodeMat.matches()) encodeString = "utf-8";
try {
return URLDecoder.decode(keywordsTmp, encodeString);
            } catch (UnsupportedEncodingException e) {
return "";
            }
        }
return "";
    }

public static String unescape(String src) {
        StringBuffer tmp = new StringBuffer();
        tmp.ensureCapacity(src.length());
int lastPos = 0, pos = 0;
char ch;
while (lastPos < src.length()) {
            pos = src.indexOf("%", lastPos);
if (pos == lastPos) {
if (src.charAt(pos + 1) == 'u') {
                    ch = (char) Integer.parseInt(src.substring(pos + 2, pos + 6), 16);
                    tmp.append(ch);
                    lastPos = pos + 6;
                } else {
                    ch = (char) Integer.parseInt(src.substring(pos + 1, pos + 3), 16);
                    tmp.append(ch);
                    lastPos = pos + 3;
                }
            } else {
if (pos == -1) {
                    tmp.append(src.substring(lastPos));
                    lastPos = src.length();
                } else {
                    tmp.append(src.substring(lastPos, pos));
                    lastPos = pos;
                }
            }
        }
return tmp.toString();
    }
}