content: /*
   * 微信公众平台(JAVA) SDK
   *
   * Copyright (c) 2014, Ansitech Network Technology Co.,Ltd All rights reserved.
   * 
   * http://www.weixin4j.org/
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.weixin4j;
  
  import org.weixin4j.util.TokenUtil;
  import java.io.IOException;
  import javax.servlet.Filter;
  import javax.servlet.FilterChain;
  import javax.servlet.FilterConfig;
  import javax.servlet.ServletException;
  import javax.servlet.ServletInputStream;
  import javax.servlet.ServletRequest;
  import javax.servlet.ServletResponse;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import org.weixin4j.spi.IMessageHandler;
  import org.weixin4j.spi.HandlerFactory;
  
  /**
   * 微信公众平台接受消息默认拦截器
   *
   * @author yangqisheng
   * @since 0.0.1
   */
  public class WeixinUrlFilter implements Filter {
  
      @Override
      public void init(FilterConfig config) throws ServletException {
          if (Configuration.isDebug()) {
              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");
          if (Configuration.isDebug()) {
              System.out.println("获得微信请求:" + request.getMethod() + " 方式");
              System.out.println("微信请求URL:" + request.getServletPath());
          }
          //消息来源可靠性验证
          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
          //Token为weixin4j.properties中配置的Token
          String token = TokenUtil.get();
          if (isGet) {
              //1.验证消息真实性
              //http://mp.weixin.qq.com/wiki/index.php?title=验证消息真实性
              //URL为http://www.weixin4j.org/api/公众号
              //成为开发者验证
              String echostr = request.getParameter("echostr");   //
              //确认此次GET请求来自微信服务器，原样返回echostr参数内容，则接入生效，成为开发者成功，否则接入失败
              if (TokenUtil.checkSignature(token, signature, timestamp, nonce)) {
                  response.getWriter().write(echostr);
              }
          } else {
              //确认此次GET请求来自微信服务器，原样返回echostr参数内容，则接入生效，成为开发者成功，否则接入失败
              if (!TokenUtil.checkSignature(token, signature, timestamp, nonce)) {
                  //消息不可靠，直接返回
                  response.getWriter().write("");
                  return;
              }
              //用户每次向公众号发送消息、或者产生自定义菜单点击事件时，响应URL将得到推送
              doPost(request, response);
          }
      }
  
      //当普通微信用户向公众账号发消息时，微信服务器将POST消息的XML数据包到开发者填写的URL上
      //用户在关注与取消关注公众号时，微信会把这个事件推送到开发者填写的URL
      //用户每次发送语音给公众号时，微信会在推送的语音消息XML数据包中，增加一个Recongnition字段
      private void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
          try {
              response.setCharacterEncoding("UTF-8");
              response.setContentType("text/xml");
              //获取POST流
              ServletInputStream in = request.getInputStream();
              if (Configuration.isDebug()) {
                  System.out.println("接收到微信输入流,准备处理...");
              }
              IMessageHandler messageHandler = HandlerFactory.getMessageHandler();
              //处理输入消息，返回结果
              String xml = messageHandler.invoke(in);
              //返回结果
              response.getWriter().write(xml);
          } catch (Exception ex) {
              ex.printStackTrace();
              response.getWriter().write("");
          }
      }
  
      @Override
      public void destroy() {
      }
  }
  