5.SpringMVC数据处理
转载:https://blog.kuangstudy.com/index.php/archives/476/
一.SpringMVC数据处理
1.数据处理的场景
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前端数据传递给后端
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提交的域名称和处理方法的参数名一致
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提交的域名称和处理方法的参数名不一致
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提交一个对象
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后端数据传递给前端
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通过ModelAndView
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通过ModelMap
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通过Model
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数据出现乱码问题
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自己写过滤器设置编码格式
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SpringMVC自带的过滤器(常用)
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终极版本的过滤器
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2.前端数据传递给后端
(1)提交的域名称和处理方法的参数名一致
提交数据 : http://localhost:8080/user/t1?name=你好 , 与处理方法参数name一致
处理方法 :
import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RequestMapping; @Controller @RequestMapping("/user") public class UserController { @GetMapping("/t1") public String test1(String name, Model model) { //1.接收前端传递来的参数 System.out.println("前端传递来的参数为:" + name); //2.返回结果传递给前端,使用Model model.addAttribute("msg",name); //3.视图跳转 return "test"; } }
(2)提交的域名称和处理方法的参数名不一致
提交数据 : http://localhost:8080/user/t2?username=你好 , 与处理方法参数不一致添加注解@RequestParam("username")
注:推荐使用注解@RequestParam,当出错时可以显示错误信息为参数错误
处理方法 :
@GetMapping("/t2") public String test2(@RequestParam("username") String name, Model model) { //1.接收前端传递来的参数 System.out.println("前端传递来的参数为:" + name); //2.返回结果传递给前端,使用Model model.addAttribute("msg",name); //3.视图跳转 return "test"; }
(3)前端提交一个对象
实体类:
import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; @Data @AllArgsConstructor @NoArgsConstructor public class User { private int id; private String name; private int age; }
提交数据 : http://localhost:8080/user/t3?name=王&id=1&age=24
注:参数名必须和对象的属性一致,否则属性值为null
处理方法:
@GetMapping("/t3") public String test3(User user) { System.out.println("前端传递来的参数为:" + user); return "test"; }
3.后端数据传递给前端
(1)通过ModelAndView(基本不用)
还要配置 <bean name="/t1" class="ustc.wzh.controller.ControllerTest1"/>
public class ControllerTest1 implements Controller { public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception { //返回一个模型视图对象 ModelAndView mv = new ModelAndView(); mv.addObject("msg","ControllerTest1"); mv.setViewName("test"); return mv; } }
(2)通过ModelMap
@GetMapping("/t4") public String test4(@RequestParam("username") String name, ModelMap model){ //封装要显示到视图中的数据 //相当于req.setAttribute("name",name); model.addAttribute("msg",name); return "test"; }
(3)通过Model(重点)
@GetMapping("/t5") public String test5(@RequestParam("username") String name, Model model){ //封装要显示到视图中的数据 //相当于req.setAttribute("name",name); model.addAttribute("msg",name); return "test"; }
(4)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。
4.数据出现乱码问题
搭建:
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前端页面
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控制器
在index.jsp同一级的目录下创建form.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>测试乱码问题</title> </head> <body> <form action="/e/t1" method="post"> <input type="text" name="name"> <input type="submit"> </form> </body> </html>
EncodingController.java
import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.PostMapping; import org.springframework.web.bind.annotation.RequestMapping; @Controller @RequestMapping("/e") public class EncodingController { @PostMapping("/t1") public String test1(String name, Model model){ model.addAttribute("msg",name); return "test"; } }
测试发现汉字乱码
(1)自己写过滤器设置编码格式
步骤:
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在controller目录同一级建立filter目录并创建EncodingFilter.java
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在web.xml中注册过滤器
EncodingFilter.java
import javax.servlet.*; import java.io.IOException; public class EncodingFilter implements Filter { public void init(FilterConfig filterConfig) throws ServletException { } public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { servletRequest.setCharacterEncoding("utf-8"); servletResponse.setCharacterEncoding("utf-8"); filterChain.doFilter(servletRequest,servletResponse); } public void destroy() { } }
在web.xml注册
注意路径 <url-pattern>/*</url-pattern>
<!--1.自定义过滤器解决乱码问题(可行)--> <filter> <filter-name>encoding</filter-name> <filter-class>ustc.wzh.filter.EncodingFilter</filter-class> </filter> <filter-mapping> <filter-name>encoding</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>
测试自定义过滤器可行
(2)SpringMVC自带的过滤器(常用)
直接在web.xml中注册即可
注意: <url-pattern>/*</url-pattern> ,有些极端情况下.这个过滤器对get的支持不好 .
<!--2.使用SpringMVC自带的过滤器处理乱码问题(可行)--> <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>
测试自定义过滤器可行
(3)终极版本的过滤器
GenericEncodingFilter.java
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; } }
注册web.xml
<filter> <filter-name>encoding</filter-name> <filter-class>ustc.wzh.filter.GenericEncodingFilter</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>
测试自定义过滤器可行