springmvc后台基于@ModelAttribute获取表单提交的数据

时间:2021-04-02 人气:0

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。

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