Spring Boot Post请求接收默认值而非传入值问题求助

我是Spring Boot新手，开发的Post请求接口始终接收默认值，而非Postman请求体中传入的实际值，请求帮助。以下是相关代码及Postman请求内容：

Postman传入的JSON #

{   
    "email": "Katie",
    "pass": "UnicornPoop",
    "city": "",
    "hairstyleType": "color"
}

Controller代码 #

package com.example.Cosmo.Budget.Tracker.controllers;
import com.example.Cosmo.Budget.Tracker.Models.WebUser;
import com.example.Cosmo.Budget.Tracker.WebUserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;


@RestController

public class CosmoController {
    //webUserRepository is an instance variable that allows me to access the records in my table.
    // WebUserRepository is the class/interface that communicates with Database/Table
    @Autowired
    private WebUserRepository webUserRepository;

    @PostMapping("/addusers")
    public String addWebUser(@RequestParam(value ="email", defaultValue = "user1") String email,
                             @RequestParam(value = "pass", defaultValue="Rih") String pass,
                             @RequestParam(value = "hairstyleType", defaultValue="shampoo")String hairstyleType,
                             @RequestParam(value = "city", defaultValue="Tampa")String city
    )
    {
        WebUser webUser = new WebUser();
        webUser.setUsername(email);
        webUser.setPassword(pass);
        webUser.setCity(city);
        webUser.setHairstyle(hairstyleType);
        webUserRepository.save(webUser);
        return "Added new users to repo!";
    }

    @GetMapping("/getusers")
    public Iterable<WebUser> getWebUser() {
        return webUserRepository.findAll();
    }
}

Model代码 #

package com.example.Cosmo.Budget.Tracker.Models;
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.Id;
  @Entity
    public class WebUser {
        @Id
        @GeneratedValue
        private Long id;
        private String email;
        private String pass;
        private String hairstyleType;
        private String city;


        public void setId(Long id) {
            this.id = id;
        }

        public WebUser(String email,
                       String pass,
                       String hairstyleType,
                       String city
        )
        {
            this.email = email;
            this.pass = pass;
            this.hairstyleType = hairstyleType;
            this.city = city;
        }

        public WebUser(){

        }

        public String getUsername() {
            return email;
        }

        public void setUsername(String email) {
            this.email = email;
        }

        public String getPassword() {
            return pass;
        }

        public void setPassword(String pass) {
            this.pass = pass;
        }

        public String getCity() {
            return city;
        }
        public void setCity(String city) {
            this.city = city;
        }
        
        public String getHairstyle() {
            return hairstyleType;
        }
        public void setHairstyle(String hairstyleType) {
            this.hairstyleType = hairstyleType;
        }

        public Long getId() {
            return id;
        }

        @Override
        public String toString() {

            return "webUser{" +
                    "id=" + id +
                    ", username='" + email + '\'' +
                    ", password='" + pass + '\'' +
                    ", hairstyleType='" + hairstyleType + '\'' +
                    ", city='" + city + '\'' +
                    '}';
        }
    }

应用启动类代码 #

package com.example.Cosmo.Budget.Tracker;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;


@SpringBootApplication
public class CosmoApplication {

    public static void main(String[] args) {
        SpringApplication.run(CosmoApplication.class, args);

    }
}

Repository代码 #

package com.example.Cosmo.Budget.Tracker;
import com.example.Cosmo.Budget.Tracker.Models.WebUser;
import org.springframework.data.repository.CrudRepository;
public interface WebUserRepository extends CrudRepository<WebUser, Long> {

}

问题原因及解决方案 #

核心问题 #

你当前使用@RequestParam接收参数，该注解用于获取URL查询参数或表单提交参数，但你在Postman中是通过JSON请求体传递参数，两者不匹配，导致接口只能读取到默认值。

修复步骤 #

1. 修改Controller方法参数：将@RequestParam替换为@RequestBody，直接接收WebUser对象，Spring会自动完成JSON请求体到实体类的映射。修改后的Controller方法如下：

   @PostMapping("/addusers")
   public String addWebUser(@RequestBody WebUser webUser) {
       webUserRepository.save(webUser);
       return "Added new users to repo!";
   }
   

   无需手动创建WebUser对象并赋值，@RequestBody会自动完成数据绑定。

2. 规范实体类的Getter/Setter（可选但建议）：你的实体类中存在属性名与Getter/Setter名称不一致的情况（如email属性对应getUsername()），虽然不影响映射，但为符合JavaBean规范，建议将getUsername()改为getEmail()、setUsername()改为setEmail()，getPassword()改为getPass()、setPassword()改为setPass()。

3. 校验Postman请求设置：确保Postman请求头中Content-Type设置为application/json，请求体选择raw->JSON格式，保证Spring能正确解析JSON数据。

验证 #

修改后重启应用，用Postman发送原JSON请求，接口即可正确接收请求体中的实际值。

内容的提问来源于stack exchange，提问作者Mimi