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【springMVC】作用域传值

SpringMVC 作用域 传值
2023-09-11 14:20:52 时间

1 前言

        上一篇博文介绍了 获取客户端数据，本文将介绍作用域传值，即将数据传递给另一个网页，有以下4种方式：

  • 通过 HttpServletRequest 传值
  • 通过 ModelAndView 传值
  • 通过 Map 传值
  • 通过 Model 传值

        注意：Map 和 Model 最终都会转换为 ModelAndView 传给客户端。

        实验需要导入的 JAR 包如下：

        笔者工作目录如下：  

        首先介绍下本文各节公共的文件，主要有 web.xml、applicationContext.xml、index.jsp、show.jsp，不同的是 Test.java，将在各节都介绍。

        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" version="3.0"> 
  	<!-- 首页网页 -->
	<welcome-file-list>
		<welcome-file>/WEB-INF/view/index.jsp</welcome-file>
	</welcome-file-list>
  
  	<!-- 配置核心(前端)控制器 DispatcherServlet -->
	<servlet>
  		<servlet-name>dispatcherServlet</servlet-name>
  		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  		<init-param>
  			<!-- 加载IOC容器配置文件 -->
  			<param-name>contextConfigLocation</param-name>
  			<param-value>classpath:applicationContext.xml</param-value> 
  		</init-param>
  	</servlet>
  	<servlet-mapping>
  		<servlet-name>dispatcherServlet</servlet-name>
  		<url-pattern>/</url-pattern>
  	</servlet-mapping>
  
  	<!-- 配置CharacterEncodingFilter，用于解决后台中文乱码 -->
	<filter>
		<filter-name>characterEncodingFilter</filter-name>
		<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
		<init-param>
			<param-name>encoding</param-name>
			<param-value>UTF-8</param-value>
		</init-param>
		<init-param>
			<param-name>forceEncoding</param-name>
			<param-value>true</param-value>
		</init-param>
	</filter>
	<filter-mapping>
		<filter-name>characterEncodingFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
</web-app>

        注意：characterEncodingFilter 用于解决客户端传递的中文参数在服务器端乱码。 

        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 http://www.springframework.org/schema/context/spring-context-4.0.xsd">	
	<!-- 扫描组件，将加@Controller注解的类作为SpringMVC的控制层 -->
	<context:component-scan base-package="com.test"></context:component-scan>
	
	<!-- 配置视图解析器 -->
	<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<property name="prefix" value="/WEB-INF/view/"></property>
		<property name="suffix" value=".jsp"></property>
	</bean>	
</beans>

        index.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<html>
<head>
	<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
	<title>首页</title>
</head>
<body>
	<form action="user" method="post"> 
		用户号：<input type="text" name="uid"><br/>
		用户名：<input type="text" name="uname"><br/>
		<input type="submit" value="提交"/>
	</form>
</body>
</html>

        show.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<html>
<head>
	<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
	<title>显示</title>
</head>
<body>
	<h1>
		用户号：${requestScope.uid}<br/>
		用户名：${requestScope.uname}<br/>
	</h1>
</body>
</html>

        注意：可以省略 requestScope，即：${uid}、${uname}

2 案例分析

2.1 通过 HttpServletRequest 传值

        Test.java

package com.test;

import javax.servlet.http.HttpServletRequest;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
public class Test {
	
	@RequestMapping(value="user",method=RequestMethod.POST)
	public String addUser(HttpServletRequest request, Integer uid, String uname) {
		request.setAttribute("uid", uid);
		request.setAttribute("uname",uname);
		return "show";
	}
}

        注意：形参列表中可以不传 uid、uname，因为 reques t的 getParameter() 方法可以获取这些参数。 

        在地址栏输入：http://localhost:8080/SpringMVC/，并填写表单，如下： 

        提交后，跳转到 show.jsp 页面，如下：

2.2 通过 ModelAndView 传值

        Test.java

package com.test;

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
public class Test {
    
	@RequestMapping(value="user",method=RequestMethod.POST)
	public ModelAndView addUser(Integer uid, String uname) {
		ModelAndView mv=new ModelAndView();
		mv.addObject("uid",uid);
		mv.addObject("uname",uname);
		mv.setViewName("show");
		return mv;
	}
}

2.3 通过 Map 传值

        Test.java

package com.test;

import java.util.Map;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
public class Test {
	
	@RequestMapping(value="user",method=RequestMethod.POST)
	public String addUser(Map<String,Object> map, Integer uid, String uname) {
		map.put("uid",uid);
		map.put("uname",uname);
		return "show";
	}
}

2.4 通过 Model 传值

        Test.java

package com.test;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
public class Test {
	
	@RequestMapping(value="user",method=RequestMethod.POST)
	public String addUser(Model model, Integer uid, String uname) {
		model.addAttribute("uid",uid);
		model.addAttribute("uname",uname);
		return "show";
	}
}

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