mybatis3.3+struts2.3.24+mysql5.1.22开发环境搭建图文教程

一、新建Web工程，并在lib目录下添加jar包
 主要jar包：struts2相关包，mybatis3.3相关包，mysql-connector-java-5.1.22-bin.jar， gson-2.1.jar

二、配置web.xml，添加一个过滤器StrutsPrepareAndExecuteFilter，处理所有*.action请求；

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
 <display-name>MS</display-name>
 <filter>
 <filter-name>struts2</filter-name>
 <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
 </filter>

 <filter-mapping>
 <filter-name>struts2</filter-name>
 <url-pattern>*.action</url-pattern>
 </filter-mapping>

 <welcome-file-list>
 <welcome-file>index.jsp</welcome-file>
 </welcome-file-list>

</web-app>

查看该过滤器doFilter源码，主要做以下几件事：
 1、判断是否设置了struts排除的url（struts.action.excludePattern，通过正则表达式匹配），如果有且当前路径符合规则，则将请求转发给过滤器链上下一个对象，不交给struts2处理

if (excludedPatterns != null && prepare.isUrlExcluded(request, excludedPatterns)) {
 chain.doFilter(request, response);
}

2、查找ActionMapping：通过PrepareOperations的findActionMapping方法查找，如果没找到，则将请求转发给过滤器链上下一个对象，不交给struts2处理；如果找到ActionMapping，则调用ExecuteOperations的executeAction方法，开始执行Action；下图是根据url找到ActionMapping的情况；

三、配置struts.xml文件,该Demo主要演示向前端传json格式数据，result type设成json格式，当然也可以设成其它的； 

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
 "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
 "http://struts.apache.org/dtds/struts-2.3.dtd">

<struts>

 <constant name="struts.devMode" value="false" />

 <package name="default" extends="struts-default,json-default">

  <global-results>
  <result type="json">
  <param name="root">json</param>
  <param name="contentType">text/html</param>
  </result>
  </global-results>

  <action name="addUser" class="ms.action.UserAction" method="addUser">
   <result>.</result>
  </action>

  <action name="queryAllUser" class="ms.action.UserAction" method="queryAllUser">
  <result>.</result>
 </action>

 </package>

 <!-- Add packages here -->

</struts>

四、配置Mybatis.xml和userMapper.xml,
 配置cacheEnabled为true, 开启二级缓存；
 配置datasource相关信息: type为POOLED-连接池形式，poolMaximumActiveConnections – 在任意时间存在的活动(也就是正在使用)连接的数量，默认值:10。
 配置实体类映射mappers             //<mapper resource="ms/model/userMapper.xml"/>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD SQL Map Config 3.0//EN"
 "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

 <settings>
 <!--开启二级缓存-->
 <setting name="cacheEnabled" value="true"/>
 </settings>

 <environments default="development">
 <environment id="development">
  <transactionManager type="JDBC" />
  <dataSource type="POOLED">
   <property name="driver" value="com.mysql.jdbc.Driver" />
   <property name="url" value="jdbc:mysql://localhost:3306/demo" />
   <property name="username" value="root" />
   <property name="password" value="admin" />
   <property name="poolMaximumActiveConnections" value="10" />
   <property name="poolPingEnabled" value="true"/>
   <property name="poolPingQuery" value="select 1 as poolPingQuery"/>
  </dataSource>
 </environment>
 </environments>
 <mappers>
  <mapper resource="ms/model/userMapper.xml"/>
 </mappers>
</configuration>

配置userMapper.xml，配置缓存为EHcache及相关参数，记得实体类要实现Serializable接口

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="UserMapper">

 <!-- 默认的cache <cache />-->
 <!-- 使用ehcache缓存 -->
 <cache type="org.mybatis.caches.ehcache.LoggingEhcache" >
 <property name="timeToIdleSeconds" value="3600"/><!--1 hour 缓存自创建日期起至失效时的间隔时间-->
 <property name="timeToLiveSeconds" value="3600"/><!--1 hour 缓存创建以后，最后一次访问缓存的日期至失效之时的时间间隔-->
 <property name="maxEntriesLocalHeap" value="1000"/>
 <property name="maxEntriesLocalDisk" value="10000000"/>
 <property name="memoryStoreEvictionPolicy" value="LRU"/>
 </cache>

 <!-- 新增-->
 <insert id="saveUser" parameterType="ms.model.User">
 insert into USER(
 account,
 name,
 address
 ) values (
 #{account},
 #{name},
 #{address}
 )
 </insert>

 <select id="queryAllUser" resultType="ms.model.User">
 select u.id,
  u.account,
  u.name,
  u.address
 from USER u
 </select>

</mapper>

五、关键代码
 DAO层：
 首先建一个类，用于获取SqlSessionFactory，设计成单例模式；

package ms.dao.base;

import java.io.IOException;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.apache.log4j.Logger;

public class MySessionFactory {

 private static SqlSessionFactory sessionFactory;
 private MySessionFactory(){

 }

 public static synchronized SqlSessionFactory getSqlSessionFactory(){
 if(sessionFactory == null){
  try {
  sessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader("mybatis-config.xml"));
  return sessionFactory;
  } catch (IOException e) {
  Logger.getLogger(MySessionFactory.class).error("getSqlSessionFactory error.");
  e.printStackTrace();
  return null;
  }
 }else{
  return sessionFactory;
 }
 }

}

接下来是UserDao，通过openSession获取SqlSession,注意这里是可以通过SqlSession的commit和rollback进行事务控制的，当然如果本来就一条sql操作，也就没什么事务控制可言了（本例子只是demo）；

package ms.dao;

import java.util.ArrayList;
import java.util.List;

import org.apache.ibatis.session.SqlSession;

import ms.dao.base.MySessionFactory;
import ms.model.User;

public class UserDao {

 public void add(User user) throws Exception{
 SqlSession session = MySessionFactory.getSqlSessionFactory().openSession();
 try {

  String statement = "UserMapper.saveUser";
  session.insert(statement, user);
  session.commit(true);

 } catch (Exception e) {
  session.rollback(true);
  e.printStackTrace();

  throw new Exception("error in add method");
 } finally {
  session.close();
 }

 }

 public List<User> queryAllUser() throws Exception{
 SqlSession session = MySessionFactory.getSqlSessionFactory().openSession();
 List<User> users = new ArrayList<User>();
 try{
  String statement = "UserMapper.queryAllUser";
  users = session.selectList(statement,1);
  session.commit(true);

 } catch (Exception e) {
  session.rollback(true);
  e.printStackTrace();
  throw new Exception("error in queryAllUser method");
 } finally {
  session.close();
 }

 return users;
 }
}

Service层：略
 Model：略
 Action层：
 转成json格式数据返回给前端；

package ms.action;

import java.io.PrintWriter;
import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import ms.model.User;
import ms.service.UserService;

import org.apache.log4j.Logger;
import org.apache.struts2.ServletActionContext;

import com.google.gson.Gson;

public class UserAction {
 Logger logger = Logger.getLogger(UserAction.class);
 private UserService userService = new UserService();
 public void addUser(){
 PrintWriter out = null;
 try{
  HttpServletRequest request = ServletActionContext.getRequest();
  HttpServletResponse response = ServletActionContext.getResponse();
  response.setContentType("text/html;charset=UTF-8");
  String account = request.getParameter("account");
  String name = request.getParameter("name");
  String address = request.getParameter("address");
  User user = new User();
  user.setAccount(account);
  user.setAddress(address);
  user.setName(name);
  userService.add(user);
  out = response.getWriter();
  out.write(new Gson().toJson("success"));
 }catch(Exception e){
  e.printStackTrace();
  logger.error(e.getMessage());
  if(out != null)
  out.write(new Gson().toJson("fail"));
 }finally{
  out.flush();
  out.close();
 }

 }

 public void queryAllUser(){
 PrintWriter out = null;
 try {
  HttpServletResponse response = ServletActionContext.getResponse();
  response.setContentType("text/html;charset=UTF-8");

  Gson gson = new Gson();
  List<User> userList= userService.queryAllUser();
  String gsonStr = gson.toJson(userList);

  out = response.getWriter();
  out.write(gsonStr);
 } catch (Exception e) {
  e.printStackTrace();
  logger.error(e.getMessage());
  if(out != null)
  out.write(new Gson().toJson("fail"));
 }finally{
  out.flush();
  out.close();
 }
 }
}

前端代码： 

<%@ page language="java" contentType="text/html; charset=UTF-8"
 pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<style>
.mt20{
 margin-top: 20px;
}
</style>
</head>
<body>

<div style="text-align: center;">
 <div class="mt20"><label>账号：</label><input id="account" type="text"/></div>
 <div class="mt20"><label>姓名：</label><input id="name" type="text"/></div>
 <div class="mt20"><label>地址：</label><input id="address" type="text"/></div>
 <div class="mt20"><button id="addUser" >添加</button></div>
</div>

<h3>用户列表:</h3>
<ul id="userList">
</ul>

<script type="text/javascript" src="js/jquery-1.11.1.min.js"></script>

<script>
 $(function() {
 $.ajax({
  url : 'queryAllUser.action',
  type : 'post',
  dataType : 'json',
  success : function(data) {
  try {
  for(var i = 0; i < data.length; i++){
   $("#userList").append("<li><span style='color:red'>id="+data[i].id+"</span>,account="+data[i].account+",name="+data[i].name+",address="+data[i].address+"</li>");
  }
  } catch (e) {};

  }
  ,
  error : function(e) {
  alert("sys error");
  }
 });

 $("#addUser").on("click", function() {
 var account = $("#account").val();
 var name = $("#name").val();
 var address = $("#address").val();
 $.ajax({
 url : 'addUser.action',
 type : 'post',
 dataType : 'json',
 data : {
  account : account,
  name : name,
  address : address
 },
 success : function(data) {
  try {

  $("#userList").append("<li>account="+account+",name="+name+",address="+address+"</li>");
  alert("添加成功");
  } catch (e) {

  }
 },
 error : function(e) {
  alert("sys error");
 }
 });

 });
 });
</script>
</body>
</html>

六、测试效果：

struts2运行正常；

测试二级缓存是否OK，查询所有User；

第一次查询：cache未命中，访问数据库：

第二次以及接下来的多次查询，cache命中，没有访问数据库：

@author   风一样的码农

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