SpringMVC原理分析 | 数据处理：ModelAndView-编程知识

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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

    <!--视图解析器--><bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver"><!--前缀--><property name="prefix" value="/WEB-INF/jsp/"/><!--后缀--><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 {@Overridepublic 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

@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 {@Overridepublic 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 {@Overridepublic void init(FilterConfig filterConfig) throws ServletException {}@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {servletRequest.setCharacterEncoding("utf-8");servletResponse.setCharacterEncoding("utf-8");filterChain.doFilter(servletRequest, servletResponse);}@Overridepublic 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

<!--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>