使用 Spring Boot 和 MyBatis 构建 REST CRUD API
大家好，这里我们将学习如何使用 Spring Boot、MyBatis 和带有 Annotation 映射的 H2 数据库开发 REST 风格的 CRUD API。您可以从我们的 Github 存储库下载源代码。
更多相关主题：
- Spring + Groovy 模板 CRUD 示例
- Spring Boot + FreeMarker + JPA - CRUD 示例
- Spring Boot + Mustache + JPA - CRUD 示例
- Spring Boot - JPA- Thymeleaf- CRUD 项目
使用的技术：
- Spring Boot 2.5.4
- Spring 5.3.9
- MyBatis 2.2.0
- Java 11
- Maven 3
完成本教程后，我们将构建什么？
我们将构建 REST API CRUD 功能：
- GET - 获取所有用户：/api/v1/users
- GET - 按 ID 获取用户：/api/v1/users/{id}
- POST - 创建用户：/api/v1/users
- PUT - 编辑用户详细信息：/api/v1/users/{id}
- DELETE - 删除用户：/api/v1/users/{id}
项目目录：
├─src│ ├─main│ │ ├─java│ │ │ └─com│ │ │ └─knf│ │ │ └─dev│ │ │ └─demo│ │ │ └─springbootmybatiscrudexample│ │ │ │ SpringbootMybatisCrudExampleApplication.java│ │ │ ││ │ │ ├─controller│ │ │ │ UserController.java│ │ │ ││ │ │ ├─exception│ │ │ │ CustomErrorResponse.java│ │ │ │ GlobalExceptionHandler.java│ │ │ │ UserIdAlreadyExistException.java│ │ │ │ UserIdNotFoundException.java│ │ │ ││ │ │ ├─model│ │ │ │ User.java│ │ │ ││ │ │ └─repository│ │ │ UserRepository.java│ │ ││ │ └─resources│ │ application.properties│ │ schema.sql
Maven 依赖项（pom.xml）
放置 mybatis -spring-boot-starter , h2依赖。
<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.5.4</version><relativePath/> <!-- lookup parent from repository --></parent><groupId>com.knf.dev.demo</groupId><artifactId>springboot-mybatis-crud-example</artifactId><version>0.0.1-SNAPSHOT</version><name>springboot-mybatis-crud-example</name><description>Demo project for Spring Boot</description><properties><java.version>11</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.2.0</version></dependency><dependency><groupId>com.h2database</groupId><artifactId>h2</artifactId><scope>runtime</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>
数据库设置
我们将创建一个名为 users 的表，其中包含一些简单的列。
我们可以通过在资源中创建一个 schema.sql 文件来初始化一个模式。
create table users(id integer not null,firstName varchar(255) not null,lastName varchar(255) not null,emailId varchar(255) not null,primary key(id));
创建用户模型
package com.knf.dev.demo.springbootmybatiscrudexample.model;public class User {private long id;private String firstName;private String lastName;private String emailId;public User() {}public User(long id,String firstName,String lastName, String emailId) {super();this.id=id;this.firstName = firstName;this.lastName = lastName;this.emailId = emailId;}public long getId() {return id;}public void setId(long id) {this.id = id;}public String getFirstName() {return firstName;}public void setFirstName(String firstName) {this.firstName = firstName;}public String getLastName() {return lastName;}public void setLastName(String lastName) {this.lastName = lastName;}public String getEmailId() {return emailId;}public void setEmailId(String emailId) {this.emailId = emailId;}}
创建用户 MyBatis 存储库
默认情况下，MyBatis-Spring-Boot-Starter 将搜索标有 @Mapper 注释的映射器。在此示例中，我们没有使用 XML 映射。
package com.knf.dev.demo.springbootmybatiscrudexample.repository;import com.knf.dev.demo.springbootmybatiscrudexample.model.User;import org.apache.ibatis.annotations.*;import java.util.List;@Mapperpublic interface UserRepository {@Select("select * from users")public List<User> findAll();@Select("SELECT * FROM users WHERE id = #{id}")public User findById(long id);@Delete("DELETE FROM users WHERE id = #{id}")public int deleteById(long id);@Insert("INSERT INTO users(id, firstName, lastName,emailId) " +" VALUES (#{id}, #{firstName}, #{lastName}, #{emailId})")public int insert(User user);@Update("Update users set firstName=#{firstName}, " +" lastName=#{lastName}, emailId=#{emailId} where id=#{id}")public int update(User user);}
创建用户休息控制器
package com.knf.dev.demo.springbootmybatiscrudexample.controller;import com.knf.dev.demo.springbootmybatiscrudexample.exception.UserIdAlreadyExistException;import com.knf.dev.demo.springbootmybatiscrudexample.exception.UserIdNotFoundException;import com.knf.dev.demo.springbootmybatiscrudexample.model.User;import com.knf.dev.demo.springbootmybatiscrudexample.repository.UserRepository;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.http.ResponseEntity;import org.springframework.web.bind.annotation.*;import java.util.HashMap;import java.util.List;import java.util.Map;@RestController@RequestMapping("/api/v1/")public class UserController {@Autowiredprivate UserRepository userRepository;// get all users@GetMapping("/users")public List<User> getAllUsers(){return userRepository.findAll();}// create user rest API@PostMapping("/users")public User createUser(@RequestBody User user) {if(userRepository.findById(user.getId())==null) {int id = userRepository.insert(user);return userRepository.findById(user.getId());}else{throw new UserIdAlreadyExistException();}}// get user by id rest api@GetMapping("/users/{id}")public ResponseEntity<User> getUserById(@PathVariable Long id) {User user = userRepository.findById(id);if(user==null){throw new UserIdNotFoundException();}return ResponseEntity.ok(user);}// update user rest api@PutMapping("/users/{id}")public ResponseEntity<User> updateUser(@PathVariable Long id,@RequestBody User userDetails) {if(userRepository.update(new User(id, userDetails.getFirstName(),userDetails.getLastName(), userDetails.getEmailId()))==0){throw new UserIdNotFoundException();}return ResponseEntity.ok(userRepository.findById(id));}// delete user rest api@DeleteMapping("/users/{id}")public ResponseEntity<Map<String, Boolean>> deleteUser(@PathVariable Long id) {userRepository.deleteById(id);Map<String, Boolean> response = new HashMap<>();response.put("deleted", Boolean.TRUE);return ResponseEntity.ok(response);}}
创建自定义异常
UserIdNotFoundException
package com.knf.dev.demo.springbootmybatiscrudexample.exception;public class UserIdNotFoundException extends RuntimeException{public UserIdNotFoundException(){super("User Id Not Found");}}
UserIdAlreadyExistException
package com.knf.dev.demo.springbootmybatiscrudexample.exception;public class UserIdAlreadyExistException extends RuntimeException{public UserIdAlreadyExistException() {super("User Id Already Exist");}}
全局异常处理程序
Spring 支持通过全局异常处理程序 (@ExceptionHandler) 和控制器建议 (@ControllerAdvice) 处理异常。这启用了一种机制，使 ResponseEntity 与 @ExceptionHandler 的类型安全和灵活性一起工作。
package com.knf.dev.demo.springbootmybatiscrudexample.exception;import org.springframework.http.HttpStatus;import org.springframework.http.ResponseEntity;import org.springframework.web.bind.annotation.ControllerAdvice;import org.springframework.web.bind.annotation.ExceptionHandler;import org.springframework.web.context.request.WebRequest;import java.time.LocalDateTime;@ControllerAdvicepublic class GlobalExceptionHandler {@ExceptionHandler(UserIdNotFoundException.class)public ResponseEntity<CustomErrorResponse>globalExceptionHandler(Exception ex, WebRequest request) {CustomErrorResponse errors = new CustomErrorResponse();errors.setTimestamp(LocalDateTime.now());errors.setError(ex.getMessage());errors.setStatus(HttpStatus.NOT_FOUND.value());return new ResponseEntity<>(errors, HttpStatus.NOT_FOUND);}@ExceptionHandler(UserIdAlreadyExistException.class)public ResponseEntity<CustomErrorResponse>globalExceptionHandler2(Exception ex, WebRequest request) {CustomErrorResponse errors = new CustomErrorResponse();errors.setTimestamp(LocalDateTime.now());errors.setError(ex.getMessage());errors.setStatus(HttpStatus.INTERNAL_SERVER_ERROR.value());return new ResponseEntity<>(errors, HttpStatus.INTERNAL_SERVER_ERROR);}}
自定义错误响应
package com.knf.dev.demo.springbootmybatiscrudexample.exception;import com.fasterxml.jackson.annotation.JsonFormat;import java.time.LocalDateTime;public class CustomErrorResponse {@JsonFormat(shape = JsonFormat.Shape.STRING,pattern = "yyyy-MM-dd hh:mm:ss")private LocalDateTime timestamp;private int status;private String error;public LocalDateTime getTimestamp(){return timestamp;}public void setTimestamp(LocalDateTime timestamp){this.timestamp = timestamp;}public int getStatus(){return status;}public void setStatus(int status){this.status = status;}public String getError(){return error;}public void setError(String error){this.error = error;}}
Spring Boot 主类
package com.knf.dev.demo.springbootmybatiscrudexample;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplicationpublic class SpringbootMybatisCrudExampleApplication {public static void main(String[] args) {SpringApplication.run(SpringbootMybatisCrudExampleApplication.class, args);}}
Spring Boot 应用程序的主类包含一个启动 Spring ApplicationContext 的公共静态 void main() 方法。
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本地设置
第 1 步：下载或克隆源代码到本地机器。
第 2 步： mvn clean install
第 3 步：运行 Spring Boot 应用程序
mvn spring-boot:run
使用 Postman 测试 API
创建用户：
获取所有用户：
通过 ID 获取用户：
更新用户：
按 ID 删除用户：
点击这里下载源代码
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