簡介

Spring+SpringMVC+MyBatis框架（SSM）是比較熱門的中小型企業級專案開發的框架，對於新手來說也是比較容易學習入門的。雖說容易，但在框架搭建過程中仍然遇到了許多問題，因此用例項記錄下來吧。

例項

第一步——導包

Spring框架包及其依賴包 
MyBatis框架包及其依賴包 
MyBatis-EhCache架包 
C3P0架包 
MySql資料庫驅動包

專案架包如下： 

專案結構如下： 

第二步——整合Dao層（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>
 

因為MyBatis交給Spring管理，因此Mapper在Spring中配置，這裡的配置只打開二級快取

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.該配置自動掃描單例化採用代理方式的Mapper，單例化的Mapper的bean名為Mapper介面第一個字母為小寫的名。 
2.千萬要注意sqlSessionFactory的bean中的configLocation屬性，其value值務必記得加上classpath:字首，不然無法載入MyBatis配置檔案

第二步——整合Service層（Spring）

業務介面和業務實現

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;
    }
}

本例項採用自動掃描載入的方式，因此該業務bean需註解@Service 
本例項交由Spring管理事務，因此該業務bean需註解@Transactional

applicationContext-service.xml

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

第三步——新增事務管理

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——整合檢視層（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>

採用mvc:annotation-driven標籤自動裝載檢視控制器處理器解析器等

檢視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;
    }
}

該Controller類需註解@Controller 
檢視控制方法需註解@RequestMapping，作為url請求處理方法

第五步——將所有配置裝載到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>

務必注意servlet-mapping中url-pattern屬性值不能為/* 
載入的配置檔案路徑必須有classpath:字首