SpringMVC入門Demo

1.MVC的流程

1. MVC模式

graph TD A(客戶) -->|發出請求request|B(Controller\Servlet) B --> C(Model\Dao,bean) C --> D(DB\Mysql) D --> C C --> B B --> |渲染到|E(view\JSP) E --> |響應|A

2. SSM：SpringMVC(完成了數據的封裝以及頁面跳轉的邏輯)，Spring，Mybatis(持久化框架ORM-Object、Relative、Mapping對象關系映射)

graph TD A(客戶) --> |SpringMVC|B(Controller\Servlet 1.接收參數 2.封裝參數\bean對象 3.調用dao 4.跳轉) B --> |Spring|C(業務層) C --> |Mybatis|D(Model\Dao,Bean)

2. SpringMVC的流程

graph TD A[客戶] -->B(控制器\Servlet\DispatcherServlet) B --> C{HandlerMapping} C -->D[controller1] C -->E[controller2] C -->F[controller3] D--> G[ModelandView] E--> G F--> G G-->H[ResoluteView] H --> A

SpringMVC的核心也是Servlet

ModelAndView的作用是保存數據，跳轉頁面

ResoluteView視圖解析器

步驟解析：

1. 客戶發出請求
2. 到達web.xml文件中DispatcherServlet查看是否符合url的要求
3. DispatcherServlet就會查看springmvc的配置文件，找HandleMapping
4. HandleMapping會根據名稱查找相應的controller
5. 執行controller類中的方法
6. 根據返回的modelandview再找到springmvc配置文件中的視圖解析器
7. 視圖解析器把viewName和prefix以及suffix做了一個拼接，把拼接的頁面展示給客戶

3.寫一個簡單的SpringMVC的Demo

1. 引入SpringMVC相關的jar包（因為是簡單的demo，所以只引入需要用的包）

2. 在主配置文件中配置DispatcherServlet

<servlet>
	<servlet-name>springMVC</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
</servlet>
<servlet-mapping>
	<servlet-name>springMVC</servlet-name>
    <url-pattern>*.do</url-pattern>
</servlet-mapping>

在瀏覽器中訪問的時候Controller第一個字母大寫，其他全部小寫，也可以省略掉Controller

3. 配置SpringMVC的配置文件

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

    <!-- <bean name="/my.do" class="com.alibaba.wlq.controller.Mycontroller"></bean> -->
    <bean class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping"></bean>
    <bean class="com.alibaba.wlq.controller.MyController1"></bean>
    <bean class="com.alibaba.wlq.controller.MyController2"></bean>
	
	<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<property name = "prefix" value="/WEB-INF/view/"/>
		<property name = "suffix" value=".jsp"/>
	</bean>

</beans>

4. controllar類中

package com.alibaba.wlq.controller;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.AbstractController;

public class MyController1 extends AbstractController{

	@Override
	protected ModelAndView handleRequestInternal(HttpServletRequest arg0, HttpServletResponse arg1) throws Exception {
		ModelAndView mv = new ModelAndView();
		mv.setViewName("login");
		mv.addObject("username","Hello World!");
		System.out.println("111111111111111");
		return mv;
	}

}

package com.alibaba.wlq.controller;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.AbstractController;

public class MyController2 extends AbstractController{

	@Override
	protected ModelAndView handleRequestInternal(HttpServletRequest arg0, HttpServletResponse arg1) throws Exception {
		ModelAndView mv = new ModelAndView();
		mv.setViewName("login");
		mv.addObject("username","Hello World!");
		System.out.println("2222222222222222");
		return mv;
	}

}

4. 常見的HandlerMapping的種類

1. BeanNameUrlHandlerMapping：根據bean標簽的名稱找到對應的Controller類
2. ControllerClassNameHandlerMapping：根據controller類的名字查找對應的Controller類

<!--根據controller類的名字查找對應的Controller-->
<bean class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping"></bean>
<!--注冊自己的controller類-->
<bean class="com.alibaba.wlq.controller.Mycontroller"></bean>

​ 3. SimpleUrlHandlerMapping：根據id查詢相應的Controller類

<!--這里包含了id與url地址的映射關系-->
<bean class="org.springframework.web.servlet.handle.SimpleUrlHandlerMapping">
    <property name = "mappings">
        <props>
            <prop key="/a.do">my1</prop>
            <prop key="/b.do">my2</prop>
        </props>
    </property>
</bean>
<!--注冊自己的controller類-->
<bean id = "my1" class = "com.alibaba.wlq.controller.MyController1"></bean>
<bean id = "my2" class = "com.alibaba.wlq.controller.MyController2"></bean>

4. 使用注解來代替配置信息（需要導入aop的jar包）

<?xml version="1.0" encoding="UTF-8"?>
	
	<beans xmlns="http://www.springframework.org/schema/beans"
 	xmlns:mvc="http://www.springframework.org/schema/mvc"
    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/mvc
    	http://www.springframework.org/schema/mvc/spring-mvc.xsd
   	 	http://www.springframework.org/schema/context
   	 	http://www.springframework.org/schema/context/spring-context.xsd">
	<!--1.包掃描：掃描注解所在的包（controller類所在的包）-->
	<context:component-scan base-package="com.alibaba.wlq.controller">
	</context:component-scan>
       
    <!-- 2.開啟注解驅動-->
	<mvc:annotation-driven />
    
	
	<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<property name = "prefix" value="/WEB-INF/view/"/>
		<property name = "suffix" value=".jsp"/>
	</bean>

</beans>

controller類中：

package com.alibaba.wlq.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class MyController3 {
	
	
	@RequestMapping("/list.do")
	public String list() {
		System.out.println("查詢所有");
		return "login";
	}
	
}

5.通過SpringMVC來完成接收參數