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" method="addUser"> <result>.</result> </action> <action name="queryAllUser" 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><label>账号：</label><input id="account" type="text"/></div> <div><label>姓名：</label><input id="name" type="text"/></div> <div><label>地址：</label><input id="address" type="text"/></div> <div><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
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持武林网。