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其实在weixin4j中，已经为大家提供了一个默认的消息接入Filter，大家只需要将jar包引入，然后配置一下web.xml和weixin4j.properties，然后部署web项目，也可以实现新手接入。
首先先展示一下默认的Filter源码
/*
* 微信公众平台(JAVA) SDK
*
* Copyright (c) 2014, Ansitech Network Technology Co.,Ltd All rights reserved.
*
* http://www.weixin4j.org/sdk/
*
* 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.message.Articles;
import org.weixin4j.message.OutputMessage;
import org.weixin4j.message.TextOutputMessage;
import org.weixin4j.message.Video;
import org.weixin4j.message.VideoOutputMessage;
import org.weixin4j.spi.IMessageHandler;
import org.weixin4j.spi.InputMessage;
import org.weixin4j.util.TokenUtil;
import org.weixin4j.util.XStreamFactory;
import com.thoughtworks.xstream.XStream;
import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Date;
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;
/**
* <p>Title: 微信公众平台接受消息拦截器</p>
*
* <p>Description: 拦截Url http://www.weixin4j.org/api/vzhanqun</p>
*
* @author weixin4j<weixin4j@ansitech.com>
*/
public class WeixinUrlFilter implements Filter {
private String _token;
private static IMessageHandler messageHandler = null;
private static String defaultHandler = "org.weixin4j.spi.DefaultMessageHandler";
@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());
}
if (isGet) {
String path = request.getServletPath();
//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
//Token为weixin4j.properties中配置的Token
//获取微信公众号
String gongzonghao = path.substring(path.lastIndexOf("/"));
//如果获取不到公众号，则向服务器发生错误信息
if (gongzonghao == null) {
response.getWriter().write("error");
} else {
//根据公众号，算出对应的Token,然后进行验证
gongzonghao = gongzonghao.substring(1);
//算出公众号的Token
_token = TokenUtil.get(gongzonghao);
if (Configuration.isDebug()) {
System.out.println("取出公众号加密后的Token:" + _token);
}
//token为空，则请求地址错误
if (!_token.equals("")) {
//成为开发者验证
doGet(request, response);
}
}
} else {
//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);
}
}
//开发者提交信息后，微信服务器将发送GET请求到填写的URL上
private void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException {
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");//
//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);
}
}
//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 {
InputMessage inputMsg = null;
OutputMessage outputMsg = null;
try {
response.setCharacterEncoding("UTF-8");
response.setContentType("text/xml");
if (messageHandler == null) {
try {
//获取
defaultHandler = Configuration.getProperty("weixin4j.handler", defaultHandler);
if (Configuration.isDebug()) {
System.out.println("微信接受消息处理Hanle:" + defaultHandler);
}
// 加载处理器
Class<?> clazz = Class.forName(defaultHandler);
try {
messageHandler = (IMessageHandler) clazz.newInstance();
} catch (Exception ex) {
System.out.println("初始化 MessageHandler 异常：");
ex.printStackTrace();
}
} catch (ClassNotFoundException ex) {
System.out.println("找不到: " + defaultHandler + " 类!");
ex.printStackTrace();
throw ex;
}
}
if (Configuration.isDebug()) {
System.out.println("IMessageHandler创建成功!");
}
//获取POST流
ServletInputStream in = request.getInputStream();
if (Configuration.isDebug()) {
System.out.println("获取POST流成功!");
}
//将POST流转换为XStream对象
XStream xs = XStreamFactory.init(false);
if (Configuration.isDebug()) {
System.out.println("将POST流转换为XStream对象成功!");
}
//将指定节点下的xml节点数据转换为对象
xs.alias("xml", InputMessage.class);
if (Configuration.isDebug()) {
System.out.println("将指定节点下的xml节点数据转换为对象成功!");
}
//将流转换为字符串
String xmlMsg = XStreamFactory.inputStream2String(in);
if (Configuration.isDebug()) {
System.out.println("获取POST的消息:[" + xmlMsg + "]");
}
//将xml内容转换为InputMessage对象
inputMsg = (InputMessage) xs.fromXML(xmlMsg);
// 取得消息类型
String MsgType = inputMsg.getMsgType();
if (Configuration.isDebug()) {
System.out.println("POST的消息类型:[" + MsgType + "]");
}
//获取消息处理方法
Method mt = messageHandler.getClass().getMethod(MsgType + "TypeMsg", InputMessage.class);
//调用处理方法，返回输出流对象
outputMsg = (OutputMessage) mt.invoke(messageHandler, inputMsg);
//如果输出流为null，则说明内部异常
if (outputMsg == null) {
//告知用户错误信息
outputMsg = new TextOutputMessage();
((TextOutputMessage) outputMsg).setContent("系统错误，请联系管理员!");
}
} catch (Exception ex) {
ex.printStackTrace();
outputMsg = new TextOutputMessage();
((TextOutputMessage) outputMsg).setContent("系统错误!");
}
try {
setOutputMsgInfo(outputMsg, inputMsg);
} catch (Exception e1) {
e1.printStackTrace();
}
// 把发送发送对象转换为xml输出
XStream xs = XStreamFactory.init(true);
xs.alias("xml", outputMsg.getClass());
xs.alias("item", Articles.class);
String xml = xs.toXML(outputMsg);
if (Configuration.isDebug()) {
System.out.println("POST输出消息:[" + xml + "]");
}
response.getWriter().write(xml);
}
//设置详细信息
private static void setOutputMsgInfo(OutputMessage oms, InputMessage msg)
throws Exception {
// 设置发送信息
Class<?> outMsg = oms.getClass().getSuperclass();
Field CreateTime = outMsg.getDeclaredField("CreateTime");
Field ToUserName = outMsg.getDeclaredField("ToUserName");
Field FromUserName = outMsg.getDeclaredField("FromUserName");
ToUserName.setAccessible(true);
CreateTime.setAccessible(true);
FromUserName.setAccessible(true);
CreateTime.set(oms, new Date().getTime());
ToUserName.set(oms, msg.getFromUserName());
FromUserName.set(oms, msg.getToUserName());
}
@Override
public void destroy() {
}
}
源码大家可以看，也可以不看。
下面教大家，直接在web.xml中，加一个Filter即可。
<!-- 默认Filter方式 微信接入配置 -->
<servlet>
<servlet-name>wechatFilter</servlet-name>
<servlet-class>org.weixin4j.WeixinUrlFilter</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>wechatFilter</servlet-name>
<url-pattern>/api/*</url-pattern>
</servlet-mapping>
最后，将项目打包，发布到服务器，就可以在微信公众号平台中，进行开发者接入认证了。
祝你部署成功，生活愉快！
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转载至：http://www.weixin4j.org/article/weixin4j-servlet.html其他文章推荐
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原文地址：http://blog.csdn.net/yakson/article/details/45250121
