【SpringMVC】005-SpringMVC返回值类型

灰太狼 2023-10-05 08:03 63阅读 0赞

# 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： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70][]

# 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： ###

### 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：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 1][]

## 3、通过request跳转页面 ##

### HelloController类： ###

### success.jsp页面： ###

### 运行结果： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 2][]

## 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： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 3][]

## 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： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 4][]

# 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： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 5][]

# 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： ###

### 运行结果： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 6][]

## 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： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 7][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200810165523700.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20200810172146831.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz,size_16,color_FFFFFF,t_70
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 3]: https://img-blog.csdnimg.cn/20200810174543669.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 4]: https://img-blog.csdnimg.cn/20200810175527113.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 5]: https://img-blog.csdnimg.cn/20200810180454823.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 6]: https://img-blog.csdnimg.cn/20200810190954110.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz,size_16,color_FFFFFF,t_70
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