springboot使用Mapping文件查询数据
时间: 2023-07-14 17:12:45 浏览: 137
Spring Boot中使用Mapping文件进行查询数据需要使用MyBatis框架,具体步骤如下:
1. 在pom.xml文件中添加MyBatis和MyBatis-Spring Boot Starter的依赖:
```xml
<!-- MyBatis依赖 -->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.2.0</version>
</dependency>
```
2. 在application.properties文件中配置数据库连接信息:
```properties
spring.datasource.url=jdbc:mysql://localhost:3306/testdb?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
```
3. 创建一个Mapping文件,例如UserMapper.xml,定义查询语句:
```xml
<?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.mapper.UserMapper">
<select id="getUserById" resultType="com.example.entity.User">
select * from user where id = #{id}
</select>
</mapper>
```
4. 创建一个User实体类,例如:
```java
public class User {
private int id;
private String name;
private int age;
// 省略getter和setter方法
}
```
5. 创建一个UserMapper接口,定义查询方法:
```java
@Mapper
public interface UserMapper {
User getUserById(int id);
}
```
6. 在Service中注入UserMapper,并调用查询方法:
```java
@Service
public class UserService {
@Autowired
private UserMapper userMapper;
public User getUserById(int id) {
return userMapper.getUserById(id);
}
}
```
7. 最后,在Controller中调用Service中的方法:
```java
@RestController
public class UserController {
@Autowired
private UserService userService;
@GetMapping("/user/{id}")
public User getUserById(@PathVariable int id) {
return userService.getUserById(id);
}
}
```
这样,就可以通过Mapping文件进行查询数据了。