简介

Spring+SpringMVC+MyBatis框架（SSM）是比较热门的中小型企业级项目开发的框架，对于新手来说也是比较容易学习入门的。虽说容易，但在框架搭建过程中仍然遇到了许多问题，因此用实例记录下来吧。

实例

第一步――导包

Spring框架包及其依赖包
MyBatis框架包及其依赖包
MyBatis-EhCache架包
C3P0架包
MySql数据库驱动包

项目架包如下：

项目结构如下：

第二步――整合Dao层（Spring+MyBatis）

sqlMapConfig.xml

<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"> <configuration>     <settings>         <setting name="cacheEnabled" value="true"/>     </settings> </configuration>

因为MyBatis交给Spring管理，因此Mapper在Spring中配置，这里的配置只打开二级缓存

applicationContext-dao.xml

    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">         <property name="driverClass" value="com.mysql.jdbc.Driver" />         <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/db_pwc" />         <property name="user" value="pwc" />         <property name="password" value="123456" />         <property name="maxPoolSize" value="20" />         <property name="minPoolSize" value="1" />         <property name="initialPoolSize" value="3" />         <property name="maxIdleTime" value="15" />     </bean>      <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">         <property name="configLocation" value="classpath:sqlMapConfig.xml" />         <property name="dataSource" ref="dataSource" />     </bean>      <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">         <property name="basePackage" value="cn.pwc.dao.mapper" />         <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />      </bean>  </beans>

1.该配置自动扫描单例化采用代理方式的Mapper，单例化的Mapper的bean名为Mapper接口第一个字母为小写的名。
2.千万要注意sqlSessionFactory的bean中的configLocation属性，其value值务必记得加上classpath:前缀，不然无法加载MyBatis配置文件

第二步――整合Service层（Spring）

业务接口和业务实现

UserService.java

package cn.pwc.service; import java.util.List; import cn.pwc.pojo.User;  public interface UserService {     public void add(User user) throws Exception;     public void delete(User user) throws Exception;     public User getUserById(int id) throws Exception;     public List<User> listUserByAge(int age) throws Exception; }

UserServiceBean.java

package cn.pwc.service.impl; import java.util.List; import javax.annotation.Resource; import org.springframework.stereotype.Service; import org.springframework.transaction.annotation.Transactional; import cn.pwc.dao.mapper.UserMapper; import cn.pwc.pojo.User; import cn.pwc.service.UserService;   @Service @Transactional public class UserServiceBean implements UserService{      @Resource(name="userMapper")     private UserMapper mapper;      @Override     public void add(User user) throws Exception {         mapper.insert(user);     }      @Override     public void delete(User user) throws Exception {         mapper.deleteById(user.getId());     }      @Override     public User getUserById(int id) throws Exception {         User user=null;         user=mapper.findById(id);         if(user==null){             throw new Exception("User is not existed!");         }         return user;     }      @Override     public List<User> listUserByAge(int age) throws Exception {         List<User> list=null;         list=mapper.findByAge(age);         if(list==null){             throw new Exception("List is empty!");         }         return list;     } }

本实例采用自动扫描加载的方式，因此该业务bean需注解@Service
本实例交由Spring管理事务，因此该业务bean需注解@Transactional

applicationContext-service.xml

    <context:component-scan base-package="cn.pwc.service" />

第三步――添加事务管理

applicationContext-transaction.xml

    <bean id="txManager"         class="org.springframework.jdbc.datasource.DataSourceTransactionManager">         <property name="dataSource" ref="dataSource" />      </bean>      <tx:annotation-driven transaction-manager="txManager" />

第四步――整合视图层（SpringMVC）

springmvc.xml

    <context:component-scan base-package="cn.pwc.controller"/>      <mvc:annotation-driven />     <bean  class="org.springframework.web.servlet.view.InternalResourceViewResolver">         <property name="prefix" value="/" />         <property name="suffix" value=".jsp" />     </bean>

采用mvc:annotation-driven标签自动装载视图控制器处理器解析器等

视图Controller（HelloController.java）

package cn.pwc.controller;  import javax.annotation.Resource;  import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.servlet.ModelAndView;  import cn.pwc.pojo.User; import cn.pwc.service.UserService;  @Controller public class HelloController {      @Resource(name="userServiceBean")     private UserService service;      @RequestMapping("/hello")     public ModelAndView sayHello(){         User user=null;         User user2=null;         User user3=null;         try {             user = service.getUserById(1);             user2=service.getUserById(1);             user3=service.getUserById(1);             System.out.println("OK!");         } catch (Exception e) {             e.printStackTrace();         }         ModelAndView view=new ModelAndView("hello");         view.addObject("user", user);         return view;     } }

该Controller类需注解@Controller
视图控制方法需注解@RequestMapping，作为url请求处理方法

第五步――将所有配置装载到Spring容器中

web.xml

<?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">     <listener>         <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>     </listener>      <context-param>         <param-name>contextConfigLocation</param-name>         <param-value>classpath:applicationContext-*.xml</param-value>     </context-param>      <servlet>         <servlet-name>springMVC</servlet-name>         <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>         <init-param>             <param-name>contextConfigLocation</param-name>             <param-value>classpath:springmvc.xml</param-value>         </init-param>      </servlet>     <servlet-mapping>         <servlet-name>springMVC</servlet-name>         <url-pattern>/</url-pattern>     </servlet-mapping>  </web-app>