【Spring MVC】---- 流程图和实例

目录

1.Spring MVC组件与流程
2.Spring MVC实例

1.Spring MVC组件与流程

组件和流程图

当一个请求到来时,DispatcherServlet首先通过请求和事先解析好的HandlerMapping配置,找到对应的处理器(Handler),准备开始运行处理器和拦截器组成的执行链,运行处理器需要有适配器(HandlerAdapter),通过适配器就能运行对应的处理器和拦截器。在处理器返回模型和视图给DispatcherServlet后,DispatcherServlet就会把对应的视图信息传递给视图解析器(ViewResolver)

具体的流程图

2.Spring MVC实例

文件结构

web.xml

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <!--配置Spring IOC配置文件路径-->
  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>/WEB-INF/applicationContext.xml</param-value>
  </context-param>
  
  <!--配置ContextLoaderListener用以初始化Spring IOC容器-->
  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>

  <!--配置DispatcherServlet-->
  <servlet>
    <!--需要配置一个/WEB-INF/dispatcher-servlet.xml文件-->
    <servlet-name>dispatcher</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!--使得Dispatcher在服务器启动的时候就初始化-->
    <load-on-startup>2</load-on-startup>
  </servlet>

  <!--Servlet拦截配置-->
  <servlet-mapping>
    <servlet-name>dispatcher</servlet-name>
    <url-pattern>*.do</url-pattern>
  </servlet-mapping>

</web-app>

• 系统变量contextConfigLocation配置会告诉Spring MVC其Spring IOC配置文件在哪里,默认值是/WEB-INF/applicationContext.xml
• ContextLoaderListener实现了接口ServletContextListener, 其作用是可以在整个Web工程前后加入自定义代码,所以可以在Web工程初始化之前,它先完成对Spring IOC容器的初始化
• 配置DIspatcherSerlvet,首先是配置了servlet-name为dispatcher,意味着需要一个/WEB-INF/dispatcher-servlet.xml文件(注意,servlet-name和文件名的对应关系)与之对应,并且设置了服务器启动时就初始化它
• 配置DispatcherServlet拦截器以后缀"do"结尾的请求,以"do"结尾的请求都会被它拦截

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" xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">

    <!--使用注解驱动-->
    <context:annotation-config/>

    <context:property-placeholder location="classpath:jdbc.properties"/>

    <!--数据库连接池-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="${db.driverClassName}"/>
        <property name="url" value="${db.url}"/>
        <property name="username" value="${db.username}"/>
        <property name="password" value="${db.password}"/>
    </bean>

    <!--集成MyBatis-->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!--数据库-->
        <property name="dataSource" ref="dataSource"/>
        <!--MyBatis全局配置文件-->
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
        <!--Mapper映射器配置路径-->
        <property name="mapperLocations" value="classpath*:mappers/*Mapper.xml"/>
    </bean>

    <!--配置数据库事务管理器-->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>

    <!--开启基于事务的注解-->
    <tx:annotation-driven transaction-manager="transactionManager"/>


    <!--采用自动扫描方式创建mapper bean-->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="cn.whc.mapper"/>
        <property name="annotationClass" value="org.springframework.stereotype.Repository"/>
    </bean>


</beans>

dispatcher-servlet.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"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">


    <!--定义扫描装载的包-->
    <context:component-scan base-package="cn.whc"/>

    <!--使用注解驱动Spring MVC-->
    <mvc:annotation-driven/>

    <!--定义视图解析器-->
    <!--找到Web工程/WEB-INF/JSP文件夹,且文件结尾为jsp的文件作为映射-->
    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

</beans>

RoleController

@Controller
@RequestMapping("/role")
public class RoleController {

    @Autowired
    private RoleService roleService = null;

    @RequestMapping(value = "/getRole", method = RequestMethod.GET)
    public ModelAndView getRole(@RequestParam("id") Long id) {
        Role role = roleService.getRole(id);
        ModelAndView mv = new ModelAndView();
        mv.addObject("role", role);
        // 指定视图类型
        mv.setView(new MappingJackson2JsonView());
        return mv;
    }
}

注意: 要添加jackson-databind这个jar包,才能显示JSON数据

效果: