SpringBoot 2.0 整合Mybatis详细步骤
=======spring boot 2.0 + Mybatis整合篇之XML，注解=======================================
1.pom.xml添加:--------------------------------------------------------------------------
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.2</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.1.9</version>
</dependency>
2.第2步分两个分支同步进行，支持XML和注解两种方式，如果SQL中没有Left join等高级关联查询，用注解方式即可解决，
如果有高级查询，需要配合XML方式写高级SQL语句。---------------------------------------------------------------
2.1 XML方式：接口类UserMapper
2.1.1 application.properties文件中添加：-----------------------------------------------------
mybatis.config-location=classpath:mybatis-config.xml
server.port=81
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.url=jdbc:mysql://localhost:3306/mybaitsdemo
spring.datasource.username=root
spring.datasource.password=
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
2.1.2 建立实体类:-------------------------------------------------------------------------------
//需要建立set get方法，此处暂且省略了。
public class User {
private Long id;
private Integer age;
private String name;
public User() {
}
}
--接口类-Dao包中-------------------------------------------------------------------
@Component
public interface UserM {
User findById(@Param("id") Long id);
}
--------------------------------------------------------------
2.1.3 resources文件夹目录添加: mybatis-config.xml文件 ---------------------------------------
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<mappers>
<mapper resource="mapper/UserMapper.xml"/>
</mappers>
</configuration>
2.1.4 resources文件夹目录添加: mapper目录,在mapper目录里添加UserMapper.xml-------------------
------------------添加完后的目录结构:resources/mapper/UserMapper.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.lemi.xxxx">
<select id="selectById" resultType="com.lemi.mydemo.entity.User">
select * from user where id = #{id}
</select>
</mapper>
2.1.5 在UserDao类中定义: 属性，sqlSession对象在spring boot加载的IOC容器中自动建立
并且把application.properties文件中配置的DataSource的值赋给sqlSession对象。------------------------------
@Component //UserDao必须加 @Component 注解，在controller中可以自动注入 @Autowired
public UserDao class{
@Autowired
private SqlSession sqlSession;
public User selectById(long id) {
return this.sqlSession.selectOne("selectById", id); //sqlSession.selectOne(String,gvr)
}
}
2.1.6 在controller包下添加：
@RestController
public class Home {
@Autowired
private UserDao userDao;
@RequestMapping("/")
public User index(){
return userDao.selectById(1);
}
}
2.1.7 运行程序测试是否正常,浏览器中输入:http:localhost:81/ ----------------------------------------------------------
2.2 注解方式：注解方式下必须要Mapper接口类-------------------------------------------------------
2.2.1 application.properties文件中添加：-----------------------------------------------------
##mybatis.config-location=classpath:mybatis-config.xml (注解方式下不需要)
server.port=81
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.url=jdbc:mysql://localhost:3306/mybaitsdemo
spring.datasource.username=root
spring.datasource.password=
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
2.2.2 建立实体类:-------------------------------------------------------------------------------
//需要建立set get方法，此处暂且省略了。
public class User {
private Long id;
private Integer age;
private String name;
public User() {
}
}
2.2.3 根据实体类建立Mapper接口类文件:UserMapper或UserM 名字随便起意义最好与实体类有关联 -------
@Component
public interface UserM {
//注解形式配置SQL
@Select("select * from user where id = #{id} ")
User findById(@Param("id") Long id);
}
2.2.4在UserDao类中定义：-------------------------------------------------------------------------
@Component
public UserDao class{
@Autowired
private UserMapper userMapper;
public User selectById(long id) {
return userMapper.findById(id);
}
}
2.2.5 在程序启动类中添加 @MapperScan("com.lemi.mydemo.dao")------------------------------------
------------------指定UserMapper接口类的包名，也可以是com.lemi.mydemo.* -----------------
@SpringBootApplication
@MapperScan("com.lemi.mydemo.dao")
public class MydemoApplication {
public static void main(String[] args) {
SpringApplication.run(MydemoApplication.class, args);
}
}
2.2.6 在controller包下添加
@RestController
public class Home {
@Autowired
private UserDao userDao;
@RequestMapping("/")
public User index(){
return userDao.selectById(1);
}
}
2.2.7 运行程序测试是否正常,浏览器中输入:http:localhost:81/ ----------------------------------------------------------
