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SpringMVC---请求与响应的处理（实战二）

 3 years ago
source link: https://segmentfault.com/a/1190000025190908
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本篇文章讲述响应的处理，关于请求的处理可以看我第一篇文章

链接地址： https://segmentfault.com/a/11...

前期准备

使用环境

  • JDK：1.8
  • Tomcat：9.0.3
  • Spring：5.2.8
  • Maven：3.6.3
  • 编译器：IntelliJ IDEA 2019

web.xml配置

<?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">
     
     <servlet> 
        <servlet-name>mvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param> 
            <param-name>contextConfigLocation</param-name>
        <param-value>classpath:ApplicationContext.xml</param-value>
        </init-param> 
    </servlet>
    <servlet-mapping> 
        <servlet-name>mvc</servlet-name>
        <url-pattern>*.do</url-pattern>
     </servlet-mapping>
</web-app>

ApplicationContext.xml配置（Spring核心配置文件）

<?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:context="http://www.springframework.org/schema/context"
 xmlns:aop="http://www.springframework.org/schema/aop"
 xmlns:mvc="http://www.springframework.org/schema/mvc"
 xsi:schemaLocation="http://www.springframework.org/schema/beans
 https://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <!-- 开启spring注解驱动-->
     <context:component-scan base-package="com.cjh"/>
    <!-- 开启mvc注解驱动-->
     <mvc:annotation-driven></mvc:annotation-driven>
</beans>

响应处理

原生的Servlet处理有直接采用response获取输出流直接响应会给浏览器，通过request转发或者重定向三种方式，现在使用spring-mvc进行响应的处理

返回String

  • "forward:资源路径名"：转发到冒号后面的资源路径
  • "redirect:资源路径名"：重定向到冒号后面的资源路径名
  • ""：如果返回的是空串，则会找index.jsp资源
  • 示例代码如下：
@Controller
public class UserController {
    
    //方法中传入实体对象：对象里面有list集合
    @RequestMapping("test.do")
    public String testFive(User user){
        System.out.println(user);
        return "redirect:welcome.jsp";
    }
}

ModelAndView

  • Model、ModelMap和ModelAndView的区别

    • Model和ModelMap只能存储返回的参数(key-value)
    • ModelAndView既能存储返回的参数，也能存储资源路径

  • ModelAndView中有两个重要的属性：

    • Object view：存储资源路径
    • ModelMap model：存储返回的参数,mvc框架会将存储的Key-value数据存入request作用域

  • 代码如下：

    • index.jsp：
    <%@ page contentType="text/html; charset=UTF-8" language="java" %>
<html>
<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <title>cai jin hong</title>
</head>
<body>
 <form action="test.do" method="post">
     account：<input type="text" name="account" value=""><br>
     password：<input type="text" name="password" value=""><br>
     balance：<input type="text" name="balance" value=""><br>
     address1:<input type="text" name="addressList[0].address" value=""><br>
     address2:<input type="text" name="addressList[1].address" value=""><br>
     <input type="submit" value="submit">
 </form></body>
</html>
    • welcome.jsp：（这时候，Jsp就能从requestScope作用域里面提取到我们存进去的account）
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
 <title>Title</title>
</head>
<body>
 param:welcome,${param.account}<br>
 requestScope:welcome,${requestScope.account}<br>
</body>
</html>
    • Java：
    @Controller
public class UserController {
     //方法中传入实体对象：对象里面有list集合
     @RequestMapping("test.do")
     public ModelAndView testFive(User user){
         //创建ModelAndView对象
         ModelAndView mv = new ModelAndView();
         //设置返回的参数
         mv.addObject("account", user.getAccount());
         mv.addObject("password", user.getBalance());
         //设置返回路径
         mv.setViewName("welcome.jsp");
         return mv;
     }
}

存入Session作用域

  • 首先，需要将参数(Key-value)存入request作用域
  • 然后通过@SessionAttributes({"key",""})注解存入Session作用域
  • 代码如下：（此时，welcome.jsp就能从SessionScope作用域里获取到account的值）
@Controller
@SessionAttributes("account")
public class UserController {
    //方法中传入实体对象：对象里面有list集合
     @RequestMapping("test.do")
     public ModelAndView testFive(User user){
         //创建ModelAndView对象
         ModelAndView mv = new ModelAndView();
         //设置返回的参数
         mv.addObject("account", user.getAccount());
         mv.addObject("password", user.getBalance());
         //设置返回路径
         mv.setViewName("welcome.jsp");
         return mv;
     }
}

report

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