使用 Spring Boot 和 MyBatis 构建 REST CRUD API

Dear 丶 2023-10-01 03:30 120阅读 0赞

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 _ Groovy _ CRUD]
 *  [Spring Boot + FreeMarker + JPA - CRUD 示例][Spring Boot _ FreeMarker _ JPA - CRUD]
 *  [Spring Boot + Mustache + JPA - CRUD 示例][Spring Boot _ Mustache _ JPA - CRUD]
 *  [Spring Boot - JPA- Thymeleaf- CRUD 项目][Spring Boot - JPA- Thymeleaf- CRUD]

#### 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：

1.  GET - 获取所有用户：/api/v1/users
2.  GET - 按 ID 获取用户：/api/v1/users/\{id\}
3.  POST - 创建用户：/api/v1/users
4.  PUT - 编辑用户详细信息：/api/v1/users/\{id\}
5.  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/4.0.0 
                https://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/> 
       </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;
    
    @Mapper
    public 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 {
        @Autowired
        private 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;
    
    @ControllerAdvice
    public 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;
    
    @SpringBootApplication
    public 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。

####  ####

#### 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：

![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAYWxsd2F5Mg_size_20_color_FFFFFF_t_70_g_se_x_16][]

获取所有用户：

![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAYWxsd2F5Mg_size_20_color_FFFFFF_t_70_g_se_x_16 1][]

通过 ID 获取用户：

![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAYWxsd2F5Mg_size_20_color_FFFFFF_t_70_g_se_x_16 2][]

更新用户：

![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAYWxsd2F5Mg_size_20_color_FFFFFF_t_70_g_se_x_16 3][]

按 ID 删除用户：

![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAYWxsd2F5Mg_size_20_color_FFFFFF_t_70_g_se_x_16 4][]

[点击这里下载源代码][Link 1]

[Spring _ Groovy _ CRUD]: https://www.knowledgefactory.net/2021/09/spring-groovy-templates-crud-example.html
[Spring Boot _ FreeMarker _ JPA - CRUD]: https://www.knowledgefactory.net/2021/09/spring-boot-freemarker-jpa-crud-example.html
[Spring Boot _ Mustache _ JPA - CRUD]: https://www.knowledgefactory.net/2021/09/spring-boot-mustache-jpa-crud-example.html
[Spring Boot - JPA- Thymeleaf- CRUD]: https://www.knowledgefactory.net/2019/09/spring-boot-jpa-thymeleaf-crud-project.html
[watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAYWxsd2F5Mg_size_20_color_FFFFFF_t_70_g_se_x_16]: https://img-blog.csdnimg.cn/8f462e7ee8d448cd98bab8c7d3bd1dd2.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBAYWxsd2F5Mg==,size_20,color_FFFFFF,t_70,g_se,x_16
[watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAYWxsd2F5Mg_size_20_color_FFFFFF_t_70_g_se_x_16 1]: https://img-blog.csdnimg.cn/b02662c23d644e088ea3afbc5bd16522.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBAYWxsd2F5Mg==,size_20,color_FFFFFF,t_70,g_se,x_16
[watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAYWxsd2F5Mg_size_20_color_FFFFFF_t_70_g_se_x_16 2]: https://img-blog.csdnimg.cn/993be6a8999347bb9575c1487e2930ca.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBAYWxsd2F5Mg==,size_20,color_FFFFFF,t_70,g_se,x_16
[watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAYWxsd2F5Mg_size_20_color_FFFFFF_t_70_g_se_x_16 3]: https://img-blog.csdnimg.cn/3d871a5465ac45f29ecb3c74415f8331.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBAYWxsd2F5Mg==,size_20,color_FFFFFF,t_70,g_se,x_16
[watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAYWxsd2F5Mg_size_20_color_FFFFFF_t_70_g_se_x_16 4]: https://img-blog.csdnimg.cn/b868814ad87b4b33b03b99551cefd808.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBAYWxsd2F5Mg==,size_20,color_FFFFFF,t_70,g_se,x_16
[Link 1]: https://github.com/knowledgefactory4u/KnowledgeFactory