package com.yunou;
import com.yunou.util.SHA1;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class WeixinUrlFilter implements Filter {

//这个Token是给微信开发者接入时填的
//可以是任意英文字母或数字，长度为3-32字符
private static String Token = "vzhanqun1234567890";

@Override
public void init(FilterConfig config) throws ServletException {
    System.out.println("WeixinUrlFilter启动成功!");
}

@Override
public void doFilter(ServletRequest req, ServletResponse res,
        FilterChain chain) throws IOException, ServletException {
    HttpServletRequest request = (HttpServletRequest) req;
    HttpServletResponse response = (HttpServletResponse) res;
    //微信服务器将发送GET请求到填写的URL上,这里需要判定是否为GET请求
    boolean isGet = request.getMethod().toLowerCase().equals("get");
    System.out.println("获得微信请求:" + request.getMethod() + " 方式");
    if (isGet) {
        //验证URL真实性
        String signature = request.getParameter("signature");// 微信加密签名
        String timestamp = request.getParameter("timestamp");// 时间戳
        String nonce = request.getParameter("nonce");// 随机数
        String echostr = request.getParameter("echostr");//随机字符串
        List<String> params = new ArrayList<String>();
        params.add(Token);
        params.add(timestamp);
        params.add(nonce);
        //1. 将token、timestamp、nonce三个参数进行字典序排序
        Collections.sort(params, new Comparator<String>() {
            @Override
            public int compare(String o1, String o2) {
                return o1.compareTo(o2);
            }
        });
        //2. 将三个参数字符串拼接成一个字符串进行sha1加密
        String temp = SHA1.encode(params.get(0) + params.get(1) + params.get(2));
        if (temp.equals(signature)) {
            response.getWriter().write(echostr);
        }
    } else {
        //处理接收消息
    }
}

@Override
public void destroy() {

}

}
目前是这样写的