$.ajax=>@ModelAttribute=null

我是一名学习Java的学生

我在学习和练习，但我问你一个问题，因为我有一个问题

通过$.ajax从join.jsp向controller发送（用户名、密码、irum、电子邮件）

从控制器获取@modeldattribute并将其移交给服务

将服务作为insert输入数据库 我在想一些事情

另外

不发送电子邮件

ID和密码规则不适用

我来写代码

join.jsp

$("#join_btn").on("click", function() {
    var formData = new FormData($("#join_form")[0]);
    for(var item of formData.entries()) {                // Normal output
        console.log(item [0]+ ' : '+ item [1]); 
    }
    alert("콘솔확인용");                                       // Normal output
    $.ajax({
        url: "/www/users/user",
        method: "post",
        data: formData,
        contentType: false,     
        processData: false      
    }).done(()=>{alert("succ")})
    .fail(()=>{alert("fail")});                     // "fail" output
});

↓

↓ 控制器

@PostMapping("/users/user")
public ResponseEntity<?> join(@ModelAttribute UserDto.Join dto) {
    System.out.println("==============================================");
    System.out.println("dto : " + dto);            // null output
    service.join(dto);
    return ResponseEntity.ok(null);
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3- 
mapper.dtd">
 <mapper namespace="com.iciamall.www.dao.UserDao">

    <insert id="insert">
         insert into users(username, password, irum, email)
         values(#{username}, #{password}, #{irum}, #{email})
    </insert>

dto

@NoArgsConstructor
public class UserDto {
  @Data
  public static class Join {
      private String username;
      private String password;
      private String irum;
      private String email;
   }
}

public interface UserDao {

public User findById(String username);
public User findByEmail(String email);
public int insert(User user);
}

dao

@NoArgsConstructor
public class UserDto {
  @Data
  public static class Join {
      private String username;
      private String password;
      private String irum;
      private String email;
   }
}

public interface UserDao {

public User findById(String username);
public User findByEmail(String email);
public int insert(User user);
}

实体

@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
@Accessors(chain=true)
public class User {
    private String username;
    private String password;
    private String irum;
    private String email;
}

userMapper

@PostMapping("/users/user")
public ResponseEntity<?> join(@ModelAttribute UserDto.Join dto) {
    System.out.println("==============================================");
    System.out.println("dto : " + dto);            // null output
    service.join(dto);
    return ResponseEntity.ok(null);
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3- 
mapper.dtd">
 <mapper namespace="com.iciamall.www.dao.UserDao">

    <insert id="insert">
         insert into users(username, password, irum, email)
         values(#{username}, #{password}, #{irum}, #{email})
    </insert>

插入用户（用户名、密码、irum、电子邮件）
值（#{username}、#{password}、#{irum}、#{email}）

=========================================================================================================

控制器 System.out.println（“dto:+dto”）； =>UserDto.Join（用户名=null，密码=null，irum=null，电子邮件=null）

控制台 =>[请求处理失败；嵌套异常为java.lang.NullPointerException:无法调用“com.iciamall.www.service.UserRestService.join（com.iciamall.www.dto.UserDto$join）”，因为“this.service”为null]