SpringMVC原理分析 | 数据处理：ModelAndView

太过爱你忘了你带给我的痛 2024-04-22 19:01 5阅读 0赞

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> 
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> 🌐Hello World ！

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### 重定向和转发 ###

#### ModelAndView ####

> 设置ModelAndView对象，根据view的名称、视图解析器跳转到指定的页面
> 
> 页面：\{视图解析器前缀\}+ viewName +\{视图解析器后缀\}

>  *  springmvc-servlet.xml
> 
>     
>         <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver">
>             
>             <property name="prefix" value="/WEB-INF/jsp/"/>
>             
>             <property name="suffix" value=".jsp"/>
>         </bean>
> 
>  *  Controller类
> 
>     //实现了Controller类说明这就是控制器
>     public class ControllerTest1 implements Controller {
>          
>         @Override
>         public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
>          
>             //创建模型和视图对象
>             ModelAndView modelAndView = new ModelAndView();
>             封装数据,向模型添加属性msg与值，可以在jsp页面取出、渲染
>             modelAndView.addObject("msg","ControllerTest1");
>             //视图跳转
>             modelAndView.setViewName("test");
>     
>             //返回视图模型对象
>             return modelAndView;
>         }
>     }

#### ServletAPI ####

> 设置ServletAPI，不需要视图解析器
> 
> 通过HttpServletResponse进行输出、重定向、转发

@Controller
    public class ModelTest1 {
        
    
        @RequestMapping("/m1/t1")
        public String test(HttpServletRequest request, HttpServletResponse response){
        
    
            HttpSession session = request.getSession();
            System.out.println(session.getId());
            return "test";
        }
    }

#### SpringMVC ####

> 通过SpringMVC实现转发和重定向，不需要视图解析器

>  *  转发
> 
>     @Controller
>     public class ModelTest1 {
>          
>     
>         @RequestMapping("/m1/t1")
>         public String test(Model model){
>          
>             //转发
>             model.addAttribute("msg","ModelTest");
>             return "/WEB-INF/jsp/test.jsp";
>             //return "forward:/WEB-INF/jsp/test.jsp";
>         }
>     }
> 
>  *  重定向
> 
>     @Controller
>     public class ModelTest1 {
>          
>     
>         @RequestMapping("/m1/t1")
>         public String test(Model model){
>          
>             //重定向
>             model.addAttribute("msg","ModelTest");
>             return "redirect:/index.jsp";
>         }
>     }

### 数据处理 ###

> 接受请求参数及数据回显，处理提交数据

#### 处理提交数据 ####

>  *  提交的域名称和处理方法的参数名`一致`
> 
>     @Controller
>     @RequestMapping("/user")
>     public class UserController {
>          
>     
>         @GetMapping("/t1")
>         public String test(String name, Model model) {
>          
>     
>             //接受前端参数
>             System.out.println("接收到前端的参数为：" + name);
>     
>             //将放回结果传递给前端
>             model.addAttribute("msg",name);
>     
>             //跳转视图
>             return "test";
>         }
>     }
> 
>  *  提交的域名称和处理方法的参数名`不一致`
> 
>     @RequestParam("username")
> 
>     @Controller
>     @RequestMapping("/user")
>     public class UserController {
>          
>     
>         @GetMapping("/t1")
>         public String test(@RequestParam("username") String name, Model model) {
>          
>     
>             //接受前端参数
>             System.out.println("接收到前端的参数为：" + name);
>     
>             //将放回结果传递给前端
>             model.addAttribute("msg",name);
>     
>             //跳转视图
>             return "test";
>         }
>     }
> 
>  *  提交是一个对象（参数名和对象名需要一致，否则返回Null）
>  *  User类
> 
>     @Data
>     @AllArgsConstructor
>     @NoArgsConstructor
>     public class User {
>          
>         private int id;
>         private String name;
>         private int age;
>     }
> 
>  *  UserController类
> 
>     @Controller
>     @RequestMapping("/user")
>     public class UserController {
>          
>         
>         @RequestMapping("/t2")
>         public String test2(User user){
>          
>             System.out.println(user);
>             return "test";
>         }
>         
>     }
>     //输出结果：User(id=1, name=weishuo, age=18)

### 数据显示到前端 ###

#### ModelAndView ####

//实现了Controller类说明这就是控制器
    public class ControllerTest1 implements Controller {
        
        @Override
        public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
        
            //创建模型和视图对象
            ModelAndView modelAndView = new ModelAndView();
            封装数据,向模型添加属性msg与值，可以在jsp页面取出、渲染
            modelAndView.addObject("msg","ControllerTest1");
            //视图跳转
            modelAndView.setViewName("test");
    
            //返回视图模型对象
            return modelAndView;
        }
    }

#### Model ####

@Controller
    @RequestMapping("/user")
    public class UserController {
        
    
        @GetMapping("/t1")
        public String test(@RequestParam("username") String name, Model model) {
        
    
            //接受前端参数
            System.out.println("接收到前端的参数为：" + name);
    
            //将放回结果传递给前端
            model.addAttribute("msg",name);
    
            //跳转视图
            return "test";
        }
    }

#### ModelMap ####

@Controller
    @RequestMapping("/user")
    public class UserController {
        
    
        @RequestMapping("/t3")
        public String test3(ModelMap map){
        
            map.addAttribute("msg","HELLO ModelMap");
            return "test";
        }
        
    }

#### 总结 ####

>  *  Model 只有寥宴几个方法只适合用于储存数据，简化了新手对于Model对象的操作和理解
>  *  ModelMap 继承了 LinkedMap，除了实现了自身的一些方法，同样的继承LinkedMap 的方法和特性
>  *  ModelAndview 可以在储存数据的同时，可以进行设置返回的逻辑视图，进行控制展示层的跳转

### 过滤器解决乱码 ###

#### Javaweb过滤器 ####

>  *  EncodingController类
> 
>     @Controller
>     public class EncodingController {
>          
>         
>         @GetMapping("/e/t1")
>         public String test1(String name, Model model, HttpServletRequest request) throws UnsupportedEncodingException {
>          
>             request.setCharacterEncoding("utf-8");
>             System.out.println(name);
>             model.addAttribute("msg",name);
>             return "test";
>         }
>     }
> 
>  *  EncodingFilter过滤器
> 
>     public class EncodingFilter implements Filter {
>          
>         @Override
>         public void init(FilterConfig filterConfig) throws ServletException {
>          
>     
>         }
>     
>         @Override
>         public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
>          
>             servletRequest.setCharacterEncoding("utf-8");
>             servletResponse.setCharacterEncoding("utf-8");
>             filterChain.doFilter(servletRequest, servletResponse);
>         }
>     
>         @Override
>         public void destroy() {
>          
>     
>         }
>     }
> 
>  *  web.xml配置过滤器
> 
>     <filter>
>         <filter-name>encoding</filter-name>
>         <filter-class>com.wei.filter.EncodingFilter</filter-class>
>     </filter>
>     <filter-mapping>
>         <filter-name>encoding</filter-name>
>         <url-pattern>/</url-pattern>
>     </filter-mapping>

### SpringMVC过滤器 ###

> SpringMVC中提供了过滤器，可以在web.xml中配置

>  *  EncodingController类
> 
>     @Controller
>     public class EncodingController {
>          
>     
>         @RequestMapping("/e/t1")
>         public String test1(String name, Model model, HttpServletRequest request) throws UnsupportedEncodingException {
>          
>             request.setCharacterEncoding("utf-8");
>             System.out.println(name);
>             model.addAttribute("msg",name);
>             return "test";
>         }
>     }
> 
>  *  web.xml配置SpringMVC乱码过滤器
> 
>     
>     <filter>
>         <filter-name>encoding</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>
>     </filter>
>     <filter-mapping>
>         <filter-name>encoding</filter-name>
>         <url-pattern>/*</url-pattern>
>     </filter-mapping>

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[wei_shuo]: https://blog.csdn.net/weixin_62765017
[wei_shuo 1]: https://bbs.csdn.net/forums/wei_shuo_study
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