关于后端:Java编程精选掌握Spring-BootMySQL和MyBatis的增删改查实战

当应用Spring Boot和MyBatis来实现对数据库的操作时，能够依照以下步骤进行配置和开发：

1. 确保曾经在我的项目的pom.xml文件中增加了Spring Boot和MyBatis的依赖。

<!-- Spring Boot 依赖 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

<!-- MyBatis 依赖 -->
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
</dependency>

<!-- MySQL 数据库驱动依赖 -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>

2. 配置数据库连贯信息。在application.properties文件中增加以下配置：

# 数据库连贯信息
spring.datasource.url=jdbc:mysql://localhost:3306/db_example
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

# MyBatis 配置
mybatis.mapper-locations=classpath:mapper/*.xml

请依据理论状况批改数据库连贯URL、用户名和明码。

3. 创立实体类（Entity）。例如，创立一个名为User的实体类，与数据库表的字段一一对应。

public class User {
    private Long id;
    private String name;
    private String email;
    // ... 其余字段的 getter 和 setter 办法
}

4. 创立Mapper接口和XML映射文件。

在UserMapper.java中定义数据库操作的办法。

@Mapper
public interface UserMapper {
    List<User> getAllUsers();

    User getUserById(Long id);

    void createUser(User user);

    void updateUser(User user);

    void deleteUser(Long id);
}

在UserMapper.xml中编写SQL语句的映射配置。

<?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.example.repository.UserMapper">
    <resultMap id="userResultMap" type="com.example.entity.User">
        <id property="id" column="id"/>
        <result property="name" column="name"/>
        <result property="email" column="email"/>
        <!-- 其余字段映射 -->
    </resultMap>

    <select id="getAllUsers" resultMap="userResultMap">
        SELECT * FROM users
    </select>

    <select id="getUserById" resultMap="userResultMap">
        SELECT * FROM users WHERE id = #{id}
    </select>

    <insert id="createUser">
        INSERT INTO users (name, email) VALUES (#{name}, #{email})
    </insert>

    <update id="updateUser">
        UPDATE users SET name = #{name}, email = #{email} WHERE id =

 #{id}
    </update>

    <delete id="deleteUser">
        DELETE FROM users WHERE id = #{id}
    </delete>
</mapper>

5. 创立服务层（Service）。在UserService.java和UserServiceImpl.java中定义对数据库操作的业务逻辑。

public interface UserService {
    List<User> getAllUsers();

    User getUserById(Long id);

    void createUser(User user);

    void updateUser(User user);

    void deleteUser(Long id);
}

@Service
public class UserServiceImpl implements UserService {
    private final UserMapper userMapper;

    public UserServiceImpl(UserMapper userMapper) {
        this.userMapper = userMapper;
    }

    @Override
    public List<User> getAllUsers() {
        return userMapper.getAllUsers();
    }

    @Override
    public User getUserById(Long id) {
        return userMapper.getUserById(id);
    }

    @Override
    public void createUser(User user) {
        userMapper.createUser(user);
    }

    @Override
    public void updateUser(User user) {
        userMapper.updateUser(user);
    }

    @Override
    public void deleteUser(Long id) {
        userMapper.deleteUser(id);
    }
}

6. 创立管制层（Controller）。在UserController.java中定义接口办法，并解决HTTP申请。

@RestController
@RequestMapping("/users")
public class UserController {
    private final UserService userService;

    public UserController(UserService userService) {
        this.userService = userService;
    }

    @GetMapping
    public List<User> getAllUsers() {
        return userService.getAllUsers();
    }

    @GetMapping("/{id}")
    public User getUserById(@PathVariable("id") Long id) {
        return userService.getUserById(id);
    }

    @PostMapping
    public void createUser(@RequestBody User user) {
        userService.createUser(user);
    }

    @PutMapping("/{id}")
    public void updateUser(@PathVariable("id") Long id, @RequestBody User user) {
        user.setId(id);
        userService.updateUser(user);
    }

    @DeleteMapping("/{id}")
    public void deleteUser(@PathVariable("id") Long id) {
        userService.deleteUser(id);
    }
}

当初，能够应用Apifox或其余API测试工具来测试这些接口。例如，发送GET申请到/users能够获取所有用户列表，发送POST申请到/users能够创立新用户，发送PUT申请到/users/{id}能够更新用户信息，发送DELETE申请到/users/{id}能够删除用户。

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