4 数据处理及跳转

4 数据处理及跳转

结果跳转方式

ModelAndView

设置 ModelAndView 对象,根据 View 的名称和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}

    <!--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>

对应的Controller类

package com.zzb.controller;import org.springframework.web.servlet.ModelAndView;import org.springframework.web.servlet.mvc.Controller;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class ControllerTest1 implements Controller {    public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {        // 创建模型视图        ModelAndView modelAndView = new ModelAndView();        // 调用业务层        String msg = "ControllerTest1";        modelAndView.addObject("msg", msg);        // 设置跳转视图        modelAndView.setViewName("test");        return modelAndView;    }}

ServletAPI

通过设置ServletAPI,不需要视图解析器

1、通过HttpServletResponse进行输出

2、通过HttpServletResponse实现重定向

3、通过HttpServletRequest实现转发

package com.zzb.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import javax.servlet.ServletException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;@Controller@RequestMapping("/t3")public class ControllerTest3 {    @RequestMapping("/t1")    public void test1(HttpServletRequest req, HttpServletResponse resp) throws IOException {        resp.getWriter().println("Hello,Spring BY servlet API");    }    @RequestMapping("/t2")    public void test2(HttpServletRequest req, HttpServletResponse resp) throws IOException {        // 重定向        resp.sendRedirect(req.getContextPath() + "/index.jsp");    }    @RequestMapping("/t3")    public void test3(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        // 转发        req.setAttribute("msg", "/t3/t3");        req.getRequestDispatcher("/WEB-INF/jsp/test.jsp").forward(req, resp);    }}

Spring MVC

通过 Spring MVC 来实现转发和重定向——不需要视图解析器。

注意:测试前先将视图解析器注释掉。

package com.zzb.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;@Controller@RequestMapping("/t4")public class ControllerTest4 {    @RequestMapping("/t1")    public String test1(){        // 转发        return "/index.jsp";    }    @RequestMapping("/t2")    public String test2(){        // 显示转发        return "forward:/index.jsp";    }    @RequestMapping("/t3")    public String test3(){        // 重定向        return "redirect:/index.jsp";    }}

通过 Spring MVC 来实现转发和重定向——使用视图解析器。

注意:开启视图解析器。

package com.zzb.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;@Controller@RequestMapping("/t5")public class ControllerTest5 {    @RequestMapping("/t1")    public String test1(){        // 转发        return "test";    }    @RequestMapping("/t2")    public String test2(){        // 重定向        return "redirect:/index.jsp";    }}

数据处理

处理提交数据

1、提交的域名数据名称和处理方法的参数名一致

package com.zzb.controller;import com.zzb.pojo.User;import org.springframework.stereotype.Controller;import org.springframework.ui.Model;import org.springframework.web.bind.annotation.RequestMapping;@Controller@RequestMapping("/data")public class DataController {    // 域名参数与控制器参数名一致的情况    @RequestMapping("/t1")    public String test1(String name, Model model){        // 1 接收前端参数        System.out.println(name);        // 2 将数据返回给前端        model.addAttribute("msg", name);        return "test";    }}

测试结果:

2、提交的域名数据名称和处理方法的参数名不一致

    // 域名参数与控制器参数名不一致的情况    @RequestMapping("/t2")    public String test2(@RequestParam("username") String name, Model model){        // 1 接受前端参数        System.out.println(name);        // 2 将参数传递给前端展示        model.addAttribute("msg", name);        return "test";    }

测试结果:

3、参数是一个对象

package com.zzb.pojo;public class User {    private  int id;    private  String name;    private int age;    public User() {    }    public User(int id, String name, int age) {        this.id = id;        this.name = name;        this.age = age;    }    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }    @Override    public String toString() {        return "User{" +                "id=" + id +                ", name='" + name + '\'' +                ", age=" + age +                '}';    }}
    // 前端提交的参数是一个对象    @RequestMapping("/t3")    public String test3(User user, Model model){        // 1 接收前端传递的参数        System.out.println(user.toString());        // 2 将参数传递给前端页面展示        model.addAttribute("msg", user.toString());        return "test";    }

测试结果:

注意:如果传递参数是对象的话,前端传递的参数名和对象的属性名必须一致,否则为null。

前端展示数据

1、ModelAndView

package com.zzb.controller;import org.springframework.web.servlet.ModelAndView;import org.springframework.web.servlet.mvc.Controller;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class ControllerTest1 implements Controller {    public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {        // 创建模型视图        ModelAndView modelAndView = new ModelAndView();        // 调用业务层        String msg = "ControllerTest1";        modelAndView.addObject("msg", msg);        // 设置跳转视图        modelAndView.setViewName("test");        return modelAndView;    }}

2、ModelMap

    @RequestMapping("/t1")    public String test1(String name, ModelMap modelMap){        // 1 接收前端参数        System.out.println(name);        // 2 将数据返回给前端        modelMap.addAttribute("msg", name);        return "test";    }

3、Model

    @RequestMapping("/t1")    public String test1(String name, Model model){        // 1 接收前端参数        System.out.println(name);        // 2 将数据返回给前端        model.addAttribute("msg", name);        return "test";    }

3种方法对比:

  • Model 只有寥寥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。

乱码问题

1、在index.jsp页面写一个表单

<%@ page contentType="text/html;charset=UTF-8" language="java" %><html>  <head>    <title>$Title$</title>  </head>  <body>  <form action=${pageContext.request.contextPath}/data/t1 method="post">    <input type="text" name="name">    <input type="submit">  </form>  </body></html>

2、后端处理程序

@Controller@RequestMapping("/data")public class DataController {    // 域名参数与控制器参数名一致的情况    @RequestMapping("/t1")    public String test1(String name, Model model){        // 1 接收前端参数        System.out.println(name);        // 2 将数据返回给前端        model.addAttribute("msg", name);        return "test";    }}

3、输入中文 哈哈哈 测试

乱码问题通过过滤器解决,Spring MVC 提供了一个过滤器,需要在web.xml中配置!

    <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>

自定义过滤器:

package com.zzb.filter;import javax.servlet.*;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletRequestWrapper;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.io.UnsupportedEncodingException;import java.util.Map;/*** 解决get和post请求 全部乱码的过滤器*/public class GenericEncodingFilter implements Filter {   @Override   public void destroy() {  }   @Override   public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {       //处理response的字符编码       HttpServletResponse myResponse=(HttpServletResponse) response;       myResponse.setContentType("text/html;charset=UTF-8");       // 转型为与协议相关对象       HttpServletRequest httpServletRequest = (HttpServletRequest) request;       // 对request包装增强       HttpServletRequest myrequest = new MyRequest(httpServletRequest);       chain.doFilter(myrequest, response);  }   @Override   public void init(FilterConfig filterConfig) throws ServletException {  }}//自定义request对象,HttpServletRequest的包装类class MyRequest extends HttpServletRequestWrapper {   private HttpServletRequest request;   //是否编码的标记   private boolean hasEncode;   //定义一个可以传入HttpServletRequest对象的构造函数,以便对其进行装饰   public MyRequest(HttpServletRequest request) {       super(request);// super必须写       this.request = request;  }   // 对需要增强方法 进行覆盖   @Override   public Map getParameterMap() {       // 先获得请求方式       String method = request.getMethod();       if (method.equalsIgnoreCase("post")) {           // post请求           try {               // 处理post乱码               request.setCharacterEncoding("utf-8");               return request.getParameterMap();          } catch (UnsupportedEncodingException e) {               e.printStackTrace();          }      } else if (method.equalsIgnoreCase("get")) {           // get请求           Map<String, String[]> parameterMap = request.getParameterMap();           if (!hasEncode) { // 确保get手动编码逻辑只运行一次               for (String parameterName : parameterMap.keySet()) {                   String[] values = parameterMap.get(parameterName);                   if (values != null) {                       for (int i = 0; i < values.length; i++) {                           try {                               // 处理get乱码                               values[i] = new String(values[i]                                      .getBytes("ISO-8859-1"), "utf-8");                          } catch (UnsupportedEncodingException e) {                               e.printStackTrace();                          }                      }                  }              }               hasEncode = true;          }           return parameterMap;      }       return super.getParameterMap();  }   //取一个值   @Override   public String getParameter(String name) {       Map<String, String[]> parameterMap = getParameterMap();       String[] values = parameterMap.get(name);       if (values == null) {           return null;      }       return values[0]; // 取回参数的第一个值  }   //取所有值   @Override   public String[] getParameterValues(String name) {       Map<String, String[]> parameterMap = getParameterMap();       String[] values = parameterMap.get(name);       return values;  }}

然后在web.xml中配置这个过滤器即可!

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