MyBatis是一款优秀的持久层框架,用于简化JDBC的开发.
本文及后续JavaWeb所创建的项目均为Maven+SpringBoot项目,用的是Aliyun的Maven仓库.
主要记录MyBatis依赖的安装过程和入门操作.
1. MyBatis的安装
1.1. 导入MyBatis依赖和MySQL驱动
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| <dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>3.0.3</version>
</dependency>
<dependency>
<groupId>com.mysql</groupId>
<artifactId>mysql-connector-j</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
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1.2. 项目结构
项目结构如下:
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| MyBatisDemo
├── src
│ ├── main
│ │ ├── java
│ │ │ └── com
│ │ │ └── example
│ │ │ └── mybatisdemo
│ │ │ ├── domain
│ │ │ │ └── pojo
│ │ │ │ └──User.java
│ │ │ ├── mapper
│ │ │ │ └── UserMapper.java
│ │ │ └── MyBatisDemoApplication.java
│ │ ├── test
│ │ │ └── java
│ │ │ └── com
│ │ │ └── example
│ │ │ └── mybatisdemo
│ │ │ └── MyBatisDemoApplicationTests.java
│ │ └── resources
│ │ └── application.properties
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1.3. 项目配置
在application.properties中配置数据库连接信息.
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spring.datasource.url=jdbc:mysql://localhost:3306/databaseName
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.username=root
spring.datasource.password=pass
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2. MyBatis的初编码
2.1. 编写Mapper接口
在src/main/java/com/example/mybatisdemo/mapper目录下创建UserMapper.
持久层接口定义SQL语句.
java文件.
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| @Mapper
public interface UserMapper {
@Select("select * from user")
List<User> selectAll();
@Insert("insert into user (username, password) values (#{username}, #{password})")
int insertUser(User user);
@Update("update user set username = #{username}, password = #{password} where id = #{id}")
int updateUser(String username, String password, int id);
@Delete("delete from user where id = #{id}")
int deleteUser(int id);
}
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2.2. 单元测试
在src/test/java/com/example/mybatisdemo/MyBatisDemoApplicationTests.java中编写单元测试.
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| @SpringBootTest
class MyBatisDemoApplicationTests {
@Autowired
private UserMapper userMapper;
@Test
void testSelectAll() {
List<User> userList = userMapper.selectAll();
for (User user : userList) {
System.out.println(user);
}
}
@Test
void testInsertUser() {
User user = new User();
user.setUsername("test");
user.setPassword("123456");
int result = userMapper.insertUser(user);
assertEquals(1, result);
}
@Test
void testUpdateUser() {
int result = userMapper.updateUser("test2", "1234567", 1);
assertEquals(1, result);
}
@Test
void testDeleteUser() {
int result = userMapper.deleteUser(1);
assertEquals(1, result);
}
}
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2.3. 调用逻辑
MyBatis的调用逻辑是通过Mapper接口与数据库进行交互的.在Spring Boot中,MyBatis会自动扫描Mapper接口并生成代理对象.
