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【SpringMVC】005-SpringMVC返回值类型

kmoon_b426 2023-02-23 阅读 48
javaspringspring mvchtmlMVCHarmonyOS后端开发


一、返回值是String类型

1、作用

controller方法返回字符串可以指定逻辑视图名，通过视图解析器解析为物理视图地址；

 

2、示例

User类：

package com.zibo.bean;

import java.io.Serializable;

public class User implements Serializable {
    private String username;
    private String password;
    private int age;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "User{" +
                "username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", age=" + age +
                '}';
    }
}

HelloController类：

package com.zibo.controller;

import com.zibo.bean.User;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestMapping;

//控制器
@Controller
public class HelloController {
    //设置路径为"/hello"
    @RequestMapping(value = "/hello")
    public String sayHello(ModelMap modelMap){
        //控制台打印"Hello Spring MVC!"
        System.out.println("Hello Spring MVC!");
        //创建一个对象，假装是从数据库查过来的
        User user = new User();
        user.setUsername("大哥");
        user.setPassword("123");
        user.setAge(20);
        //存入request域对象
        modelMap.addAttribute("user",user);
        //返回success.jsp页面
        return "success";
    }
}

index.jsp页面：

<%--
  Created by IntelliJ IDEA.
  User: ZiBo
  Date: 2020/8/9
  Time: 14:52
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h3>入门程序！</h3>
    <a href="hello">点我调转到success.jsp页面</a>
</body>
</html>

success.jsp页面：

<%--
  Created by IntelliJ IDEA.
  User: ZiBo
  Date: 2020/8/9
  Time: 15:05
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h1>入门成功！</h1>
<%--    取数据--%>
    ${ requestScope.get("user").username }
    <br/>
    ${ user.username }
    <br/>
    ${ user.password }
    <br/>
    ${ user.age }
</body>
</html>

备注：其他代码（环境）参考SpringMVC入门程序；

运行结果：

【SpringMVC】005-SpringMVC返回值类型_java

 

二、返回值是void

1、说明

我们可以通过Servlet原始API中的request和response控制响应结果，进行页面跳转；

 

2、简单示例

HelloController类：

package com.zibo.controller;

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

//控制器
@Controller
public class HelloController {
    //设置路径为"/hello"
    @RequestMapping(value = "/hello")
    public void sayHello(){
        //控制台打印"Hello Spring MVC!"
        System.out.println("Hello Spring MVC!");
    }
}

说明：

只写这么多，服务器默认回去访问XXX/hello.jsp页面，这是不可取的，运行结果如下图：

【SpringMVC】005-SpringMVC返回值类型_spring_02

 

3、通过request跳转页面

HelloController类：

package com.zibo.controller;

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

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

//控制器
@Controller
public class HelloController {
    //设置路径为"/hello"
    @RequestMapping(value = "/hello")
    public void sayHello(HttpServletRequest request, HttpServletResponse response) throws Exception {
        //控制台打印"Hello Spring MVC!"
        System.out.println("Hello Spring MVC!");
        //使用request进行请求转发
        request.getRequestDispatcher("/WEB-INF/pages/success.jsp").forward(request,response);
    }
}

success.jsp页面：

<%--
  Created by IntelliJ IDEA.
  User: ZiBo
  Date: 2020/8/9
  Time: 15:05
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h1>入门成功！</h1>
</body>
</html>

运行结果：

【SpringMVC】005-SpringMVC返回值类型_spring_03

 

4、通过重定向跳转页面

HelloController类：

package com.zibo.controller;

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

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

//控制器
@Controller
public class HelloController {
    //设置路径为"/hello"
    @RequestMapping(value = "/hello")
    public void sayHello(HttpServletRequest request, HttpServletResponse response) throws Exception {
        //控制台打印"Hello Spring MVC!"
        System.out.println("Hello Spring MVC!");
        //使用request进行请求转发
//        request.getRequestDispatcher("/WEB-INF/pages/success.jsp").forward(request,response);
        //重定向跳转,重定向不能直接定向到/WEB-INF/pages/下的success.jsp
        response.sendRedirect(request.getContextPath() + "/redirect.jsp");
    }
}

redirect.jsp页面：

<%--
  Created by IntelliJ IDEA.
  User: ZiBo
  Date: 2020/8/10
  Time: 17:38
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h1>重定向到达的页面！</h1>
</body>
</html>

运行结果：

【SpringMVC】005-SpringMVC返回值类型_MVC_04

 

5、直接进行响应

HelloController类：

package com.zibo.controller;

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

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

//控制器
@Controller
public class HelloController {
    //设置路径为"/hello"
    @RequestMapping(value = "/hello")
    public void sayHello(HttpServletResponse response) throws Exception {
        //控制台打印"Hello Spring MVC!"
        System.out.println("Hello Spring MVC!");
        //使用request进行请求转发
//        request.getRequestDispatcher("/WEB-INF/pages/success.jsp").forward(request,response);
        //重定向跳转,重定向不能直接定向到/WEB-INF/pages/下的success.jsp
//        response.sendRedirect(request.getContextPath() + "/redirect.jsp");
        //直接进行响应
        //设置编码，解决中文乱码
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        //响应
        response.getWriter().println("<h1>直接进行响应</h1>");
    }
}

运行结果：

【SpringMVC】005-SpringMVC返回值类型_spring_05

 

三、返回值是ModelAndView类型

1、作用

ModelAndView对象是SpringMVC提供的一个对象，可通过视图解析器跳转页面；

 

2、示例

HelloController类：

package com.zibo.controller;

import com.zibo.bean.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

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

//控制器
@Controller
public class HelloController {
    //设置路径为"/hello"
    @RequestMapping(value = "/hello")
    public ModelAndView sayHello() {
        //控制台打印"Hello Spring MVC!"
        System.out.println("Hello Spring MVC!");
        //使用ModelAndView实现页面跳转
        ModelAndView mv = new ModelAndView();
        //创建一个对象，假装是从数据库查过来的
        User user = new User();
        user.setUsername("大哥");
        user.setPassword("123");
        user.setAge(20);
        mv.addObject("user",user);
        //设置要跳转的页面
        mv.setViewName("success");
        return mv;
    }
}

success.jsp页面：

<%--
  Created by IntelliJ IDEA.
  User: ZiBo
  Date: 2020/8/9
  Time: 15:05
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h1>入门成功！</h1>
    ${ user.username }<br/>
    ${ user.password }<br/>
    ${ user.age }
</body>
</html>

运行结果：

【SpringMVC】005-SpringMVC返回值类型_spring mvc_06

 

四、使用关键字的方式进行转发和重定向（不常用）

1、转发示例

HelloController类：

package com.zibo.controller;

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

//控制器
@Controller
public class HelloController {
    //设置路径为"/hello"
    @RequestMapping(value = "/hello")
    public String sayHello() {
        //控制台打印"Hello Spring MVC!"
        System.out.println("Hello Spring MVC!");
        //转发
        return "forward:/WEB-INF/pages/success.jsp";
    }
}

success.jsp页面：

<%--
  Created by IntelliJ IDEA.
  User: ZiBo
  Date: 2020/8/9
  Time: 15:05
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h1>入门成功！</h1>
</body>
</html>

运行结果：

【SpringMVC】005-SpringMVC返回值类型_html_07

 

2、重定向示例

HelloController类：

package com.zibo.controller;

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

//控制器
@Controller
public class HelloController {
    //设置路径为"/hello"
    @RequestMapping(value = "/hello")
    public String sayHello() {
        //控制台打印"Hello Spring MVC!"
        System.out.println("Hello Spring MVC!");
        //转发
//        return "forward:/WEB-INF/pages/success.jsp";
        //重定向-注意不能重定向到WEB-INF文件夹下，也不需要再写项目名称
        return "redirect:redirect.jsp";
    }
}

运行结果：

【SpringMVC】005-SpringMVC返回值类型_html_08

 

 

 

 

 

 

 

 

 

 

 

 

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