Spring Boot CRUD应用POST请求返回404错误问题求助

问题概述 #

开发基于PostgreSQL的Spring Boot CRUD应用时，@GetMapping请求可正常返回空对象数组，但@PostMapping请求返回404错误。此前使用@RequestMapping("api/v1/customers")时收到405错误，修改为@RequestMapping(name = "api/v1/customers" ,method = RequestMethod.POST)后变为404错误。同时customerRepository.save(customer)不允许将依赖注入设为final，IDEA建议设为static但无效。

代码问题分析 #

1. 请求映射配置错误 #

• 类级别@RequestMapping误用name属性：name仅作为路径别名，不会实际映射请求路径；同时指定method = RequestMethod.POST会限制整个类的请求只能是POST，导致原本正常的@GetMapping请求出现405（方法不允许）。
• @PostMapping注解位置错误：放在了内部record类NewCustomerRequest中，Spring无法识别该类中的控制器方法，因为record未被标记为控制器组件。

2. 依赖注入错误 #

使用static修饰CustomerRepository，Spring容器管理的Bean实例不应为静态，静态成员会脱离容器的生命周期管理，导致依赖注入失效。

修复后的代码 #

SpringRecapApplication.java #

package com.example.SpringRecap;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@SpringBootApplication(exclude = SecurityAutoConfiguration.class)
@RequestMapping("api/v1/customers") // 正确使用value属性映射基础路径
public class SpringRecapApplication {
    // 使用final修饰，依赖注入由Spring容器管理
    private final CustomerRepository customerRepository;

    // 构造注入，无需static
    public SpringRecapApplication(CustomerRepository customerRepository) {
        this.customerRepository = customerRepository;
    }

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

    @GetMapping
    public List<Customer> getCustomer() {
        return customerRepository.findAll();
    }

    // 将PostMapping方法移到类级别，作为控制器方法
    @PostMapping
    public void addCustomer(@RequestBody NewCustomerRequest newCustomerRequest) {
        Customer customer = new Customer();
        customer.setAge(newCustomerRequest.age());
        customer.setName(newCustomerRequest.name());
        customer.setEmail(newCustomerRequest.email());
        customerRepository.save(customer);
    }

    // 仅作为DTO的record，无需注解
    record NewCustomerRequest(
            String name,
            String email,
            Integer age
    ) {}
}

CustomerRepository.java（无需修改） #

package com.example.SpringRecap;

import org.springframework.data.jpa.repository.JpaRepository;

public interface CustomerRepository extends JpaRepository<Customer,Integer> {
}

Customer.java（无需修改） #

package com.example.SpringRecap;

import jakarta.persistence.*;

import java.util.Objects;

@Entity
public class Customer {
    @Id
    @SequenceGenerator(
            name = "customer_id_sequence",
            sequenceName = "customer_id_sequence",
            allocationSize = 1

    )
    @GeneratedValue(
            strategy = GenerationType.SEQUENCE,
            generator = "customer_id_sequence"

    )
    private Integer id;
    private String name;
    private String email;
    private Integer age;

    public Customer(Integer id, String name, String email, Integer age) {
        this.id = id;
        this.name = name;
        this.email = email;
        this.age = age;
    }

    public Customer() {

    }


    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

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

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Customer customer = (Customer) o;
        return Objects.equals(id, customer.id) && Objects.equals(name, customer.name) && Objects.equals(email, customer.email) && Objects.equals(age, customer.age);
    }

    @Override
    public int hashCode() {
        return Objects.hash(id, name, email, age);
    }

    @Override
    public String toString() {
        return "Customer{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", email='" + email + '\'' +
                ", age=" + age +
                '}';
    }
}

测试验证 #

修复后，使用Postman发送POST请求到http://localhost:8080/api/v1/customers，请求体使用JSON格式：

{
    "name": "Test User",
    "email": "test@example.com",
    "age": 25
}

此时请求应返回200状态码，数据成功存入PostgreSQL数据库；@GetMapping请求http://localhost:8080/api/v1/customers可返回新增的用户数据。

内容的提问来源于stack exchange，提问作者Nimasha Madhushani