springmvc后台基于@ModelAttribute获取表单提交的数据
时间：2020-11-14 11:33:48 | 栏目：JAVA代码 | 点击：次
1、通过注解ModelAttribute直接映射表单中的参数到POJO。在from中的action写提交的路径，在input的name写参数的名称。
POJO
package com.demo.model;
public class user {
private String username;
private String password;
private int nsex;
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 void setNsex(int nsex) {
this.nsex = nsex;
}
public int getNsex() {return nsex;}
}
FORM
<%--
Created by IntelliJ IDEA.
User: wym
Date: 2019/10/8
Time: 23:17
To change this template use File | Settings | File Templates.
--%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Login</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/login" method="post">
用户名：<input type="text" name="username"/> <br><br>
密码：<input type="password" name="password"/> <br><br>
<input type="submit" value="提交"/>
</form>
</body>
</html>
CONTROLLER
package com.demo.controller;
import com.demo.model.user;
import com.demo.service.Userservice;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import javax.servlet.http.HttpSession;
@Controller
public class LoginController {
@Autowired
private Userservice userService;
@RequestMapping(value="/login", method= RequestMethod.POST)
public String hello(@ModelAttribute user u, HttpSession session){
session.setAttribute("user", u);
user user = userService.findbyname(u.getUsername());
if(user == null)
return "loginfail";
else if(!user.getPassword().equals(u.getPassword()))
return "falsepaswd";
else
return "helloworld";
}
}
注意！！这里只有input的参数name名称和pojo中的成员域名称完全相同才可以通过@ModelAttribute进行直接映射，否则无法被赋值的参数将会以默认值的方式呈现。
2.显然不可能form获取的内容总是某个pojo的属性，完全有可能是单独出现的。这时可以使用@RequestParam获取参数。
public String hello(@RequestParam(value="username") String A, @RequestParam(value="password") String B, HttpSession session){
session.setAttribute("a", A);
session.setAttribute("b", B);
user user = userService.findbyname(A);
if(user == null)
return "loginfail";
else if(!user.getPassword().equals(B))
return "falsepaswd";
else
return "helloworld";
}
这时候只需跟在@RequestParam后的参数和form的name一致即可，String的名称可以随便取。
3.可以直接啥注解都不加，只需保证参数名称和form的name即可
public String hello( String username, String password, HttpSession session){
session.setAttribute("a", username);
session.setAttribute("b", password);
user user = userService.findbyname(username);
if(user == null)
return "loginfail";
else if(!user.getPassword().equals(password))
return "falsepaswd";
else
return "helloworld";
}
4.通过HttpServletRequest接收
public String hello( HttpServletRequest req, HttpSession session){
username=req.getParameter("username");
password=req.getParameter("password");
session.setAttribute("a", username);
session.setAttribute("b", password);
user user = userService.findbyname(username);
if(user == null)
return "loginfail";
else if(!user.getPassword().equals(password))
return "falsepaswd";
else
return "helloworld";
}
此外，还有一些其他的方式接受数据，例如通过@RequestBody等方式传递json数据。