SSM整合

SSM整合

在这之前我们已经学习了如何整合Spring和web项目,若要整合Spring,SpringMVC,Mybatis时,只需要在其基础上加入SpringMVC和MyBatis就可以了;

整合步骤:

1.准备空的web项目

2.在web.xml中配置Spring容器

3.在web.xml中配置SpringMVC核心控制器

4.整合MyBatis与Spring

pom依赖:

主要依赖类别:,webmvc(会自动依赖Spring其他核心jar) , web基础的(jstl,jsp,servlet),mybatis ,事务管理, AspectJ

  <dependencies>
<!--    spring   + springwebmvc-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.2.2.RELEASE</version>
    </dependency>

<!--    mybatis-->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>2.0.3</version>
    </dependency>

    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.2</version>
    </dependency>

<!--    JDBC-->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.44</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <version>5.2.2.RELEASE</version>
    </dependency>

    <!--事务管理-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-tx</artifactId>
      <version>5.2.2.RELEASE</version>
    </dependency>


    <!--AspectJ-->
    <dependency>
      <groupId>org.aspectj</groupId>
      <artifactId>aspectjweaver</artifactId>
      <version>1.8.0</version>
    </dependency>


<!--    jstl   jsp  servlet-->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>

    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>javax.servlet.jsp-api</artifactId>
      <version>2.3.3</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>4.0.1</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>

springmvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">	
  <!--扫描Controller所在的包-->
    <context:component-scan base-package="com.kkb.controller"/>
</beans>

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">

  	<!--mybatis -->
    <context:property-placeholder location="classpath:jdbc.properties" system-properties-mode="NEVER"/>
    <bean name="dataSouce" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="url" value="${url}"/>
        <property name="username" value="${user}"/>
        <property name="password" value="${password}"/>
        <property name="driverClassName" value="${driver}"/>
    </bean>

    <bean class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSouce"/>
    </bean>

    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="com.kkb.dao"/>
    </bean>
  	<!--mybatis END -->
  
  	<!--注解扫描 -->
    <context:component-scan base-package="com.kkb.service"/>

</beans>
<!--别忘记自行准备一个jdbc.properties数据库相关配置文件-->

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
<!--    Spring-->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicationContext.xml</param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
<!--    Spring END-->

<!--    SpringMVC-->
    <servlet>
        <servlet-name>dispatcherServlet</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>
        <load-on-startup>1</load-on-startup>
    </servlet>
    
    <servlet-mapping>
        <servlet-name>dispatcherServlet</servlet-name>
        <url-pattern>*.action</url-pattern>
    </servlet-mapping>
<!--    SpringMVC END-->
</web-app>

MyController.java

@Controller
public class MyController {

    @Autowired
    private CourseService courseService;

    @RequestMapping("/courseList.action")
    public ModelAndView courseList(){
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.setViewName("courses.jsp");
        modelAndView.addObject("courses",courseService.selectCourseList());
        return modelAndView;
    }
}
//别忘记CourseService注册到容器,注入Mapper 进行查询 篇幅太大不放了

courses.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<html>
<head>
</head>
<body>
<table border="1">
    <tr>
        <th>名称</th>
        <th>讲师</th>
        <th>开课日期</th>
        <th>学分</th>
        <th>课时</th>
        <th>操作</th>
    </tr>
    <c:forEach items="${courses}" var="course">
        <tr>
            <td>${course.name}</td>
            <td>${course.teachName}</td>
            <td>
                <fmt:formatDate value="${course.startTime}" pattern="yyyy-MM-dd"/>
            </td>
            <td>${course.score}</td>
            <td>${course.hours}</td>
            <td>
                <a href="editCourse?id=${course.id}">修改</a>
            </td>
        </tr>
    </c:forEach>
</table>
</body>
</html>

配置完成后启动服务器,访问:http://localhost:8080/SSMTest/courseList.action

案例中设计到的mapper,pojo以及SQL使用MyBatis逆向生成的;

到此SSM的整合就完成了; (事务配置和其他配置均与Spring项目没有区别)

事务AOP等配置与单独的Spring没有区别,但不过要注意现在有两个Spring配置文件,别写错位置;

Spring与SpringMVC容器关系:

SpringMVC容器固然是一个拥有Spring所有功能的容器,但是为了分离关注点,通常SpringMVC容器只处理与请求响应相关的内容,即Controller层;

Spring框架采用了父子容器的方式来实现分离关注点;实际上SpringMVC被作为了Spring的子容器;如下所示:

外层的Spring容器为父容器,里面的SpringMVC为子容器,要强调的是其他的框架并不是容器,只是容器中的一堆Bean;

职责分配:

• Spring容器主要负责集成其他框架,配置AOP,事务
• SpringMVC容器负责处理请求响应即Controller层

特点:

• 子容器可直接访问父容器中的Bean,而父容器不能访问子容器的Bean
• 子容器优先从自身里查找Bean,找不到时才会找父容器

容易出的问题:

事务处理通常在父容器中配置,因为MyBatis相关Bean是由父容器管理的,假设已经在父容器为Service层配置了事务,子容器没有配置事务,但是子容器却扫描了Service层,这时候事务就不生效了,因为子容器中有ServiceBean,但是却没有事务;