初识springmvc_01

Posted 2020-06-13

1.DispatcherServlet：前端控制器，用于接收请求。(即spring mvc是基于servlet实现的所以要注意多线程问题)

2.HandlerMapping接口：DefaultAnnotationHandlerMapping :HandlerMapping接口的实现, 用于处理请求的映射。即前端请求找到对应的controller

3.HandlerAdapter接口：AnnotationMethodHandlerAdapter: HandlerAdapter接口的实现，用于处理请求的映射。根据前端请求找到controller的方法

4.ViewResolver接口：InternalResourceViewResolver : ViewResolver接口的实现，用于把ModelAndView的逻辑视图名解析为具体的View。

前端请求过来，通过DefaultAnnotationHandlerMapping(注解) 找到对应的Controller，然后通过AnnotationMethodHandlerAdapter找到处理请求的方法，方法处理完后，通过InternalResourceViewResolver返回到哪个视图；

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" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:util="http://www.springframework.org/schema/util" 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/util
  http://www.springframework.org/schema/util/spring-util.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">
  
  
  
      <!-- 匹配请求和Controller有两种写法 -->
  
  
      <!-- 第一种请求直接对应Controller类(默认使用) -->
    <!-- BeanNameUrlHandlerMapping -->
    <!--
    <bean id="/hello" class="com.controller.HelloController"></bean>
    <bean id="/hello_2" class="com.controller.HelloController_2"></bean>
     -->


    <!-- 第二种Controller类标注自己的id，然后通过HandlerMapping集体对应 -->
    <!-- SimpleUrlHandlerMapping -->
    <!--
    <bean id="helloController" class="com.controller.HelloController"></bean>
    <bean id="helloController_2" class="com.controller.HelloController_2"></bean>
    <bean id="simpleUrlHandlerMapping"
        class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
        <property name="mappings">
             <props>
                     <prop key="/helloTest_2">helloController_2</prop>
                     <prop key="/helloTest">helloController</prop>
             </props>
        </property>
    </bean>
    -->
    
    <!-- 一个Controller写多个方法 -->
    <bean id="paramMethodResolver" class="org.springframework.web.servlet.mvc.multiaction.ParameterMethodNameResolver">
        <property name="paramName" value="action"></property>    
    </bean>
     <bean name="/multi" class="com.controller.MultiController">
        <property name="methodNameResolver">
            <ref bean="paramMethodResolver"/>
        </property>
    </bean>
    
    

    <!-- 注解映射方式 -->
    <mvc:annotation-driven />
    <!-- 如果当前请求为“/”时，则转发到“/helloworld/index” -->
    <mvc:view-controller path="/" view-name="forward:/annotationController/helloworld" />
    <!-- 开启controller注解支持 -->
    <!-- use-default-filters="false" 只扫描指定的注解 -->
    <context:component-scan base-package="com.controller"
        use-default-filters="false">
        <context:include-filter type="annotation"
            expression="org.springframework.stereotype.Controller" />
    </context:component-scan>

    
    <!-- 视图解析器 -->
    <bean
        class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass"
            value="org.springframework.web.servlet.view.JstlView" />
        <property name="contentType" value="text/html" />
        <property name="prefix" value="/WEB-INF/views/" />
        <property name="suffix" value=".jsp" />
    </bean>
    <!-- 支持上传文件 -->
    <bean id="multipartResolver"
        class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <!-- 设置上传文件的最大尺寸为1MB -->
        <property name="maxUploadSize">
            <value>1048576</value>
        </property>
        <property name="defaultEncoding">
            <value>UTF-8</value>
        </property>
    </bean>
</beans>

Controller实现：

package com.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

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


/**
 *    一个类一个Controller,一个请求
 */
public class HelloController extends AbstractController{

    @Override
    protected ModelAndView handleRequestInternal(HttpServletRequest arg0,
            HttpServletResponse arg1) throws Exception {
        
        System.out.println("............HelloController.................");
        
        return new ModelAndView("index");
    }

}

package com.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 HelloController_2 extends AbstractController{

    @Override
    protected ModelAndView handleRequestInternal(HttpServletRequest arg0,
            HttpServletResponse arg1) throws Exception {
        
        
        System.out.println("............HelloController_2.................");
        
        return new ModelAndView("index");
    }

}

一个类一个Controller，可以对应多个请求:

package com.controller;


import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.mvc.multiaction.MultiActionController;


/**
 *    一个类一个Controller，可以对应多个请求
 *在一个Controller类中定义多个方法，并根据使用者的请求来执行当中的某个方法，
 *相当于Struts的DispatcherAction。
 *使用MultiActionController需要配个MethodNameResolver实例，
 *默认使用ParameterMethodNameResolver，他会根据所给的网址中，
 *最后请求的文件名称来判断执行Controller中的哪一个方法
 *
 *MultiActionController 也实现了AbstractController类,实现了handleRequestInternal方法
 *    @Override
    protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response)
            throws Exception {
        try {
            //通过请求找到方法名
            String methodName = this.methodNameResolver.getHandlerMethodName(request);
            //然后调用具体的方法(注意＊＊＊＊参数：request，response＊＊＊＊＊＊＊＊)
            return invokeNamedMethod(methodName, request, response);
        }
        catch (NoSuchRequestHandlingMethodException ex) {
            return handleNoSuchRequestHandlingMethod(ex, request, response);
        }
    }
 */
public class MultiController extends MultiActionController{
    
    
    public String add(HttpServletRequest request,
            HttpServletResponse response){
        System.out.println("-----------add------------");
        return "index";
    }
    
    public String delete(HttpServletRequest request,
            HttpServletResponse response){
        System.out.println("------------delete--------------");
        return "index";
    }
    
    public String update(HttpServletRequest request,
            HttpServletResponse response){
        System.out.println("---------------update---------------");
        return "index";
    }    
}

基于注解实现Controller：

package com.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;

@Controller
@RequestMapping(value = "annotationController")
public class AnnotationController {

    @RequestMapping(value = "/helloworld", method = { RequestMethod.GET })
    protected ModelAndView helloworld() {
        System.out.println("............HelloController_3.................");
        return new ModelAndView("index");
    }

}

WebContent/views/下的视图：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
    hello word!!!
</body>
</html>