前言
前一篇中我們使用spring boot+mybatis創建了單一數據源，其中單一數據源不需要我們自己手動創建，spring boot自動配置在程序啟動時會替我們創建好數據源。
准備工作
application.yml中配置connection的4個屬性
spring:
datasource:
read:
driver-class-name: com.mysql.jdbc.Driver
url: jdbc:mysql://192.168.80.129:3306/test
username: root
password: 123456
write:
driver-class-name: com.mysql.jdbc.Driver
url: jdbc:mysql://192.168.80.129:3306/test
username: root
password: 123456
多數據源創建方法
1、多數據源主要是需要我們手動來創建DataSource、SqlSessionFactory、SqlSessionTemplate。這里我們基於同一個庫來創建讀寫分離的數據源。這里兩個方法的返回值都是javax.sql.DataSource。
@Configuration
public class DataSourceConfig {
@Primary
@Bean(name="readDataSource")
@ConfigurationProperties(prefix = "spring.datasource.read")
public DataSource readDataSource(){
return DataSourceBuilder.create().build();
}
@Bean(name="writeDataSource")
@ConfigurationProperties(prefix = "spring.datasource.write")
public DataSource writeDataSource(){
return DataSourceBuilder.create().build();
}
}
2、讀寫分離的配置類。也就是分別創建讀寫的SqlSessionFactory和SqlSessionTemplate
@Configuration
@MapperScan(basePackages = {"com.zhangfei.dao.read"},sqlSessionFactoryRef = "readSqlSessionFactory")
public class MyBatisDbAConfig {
@Autowired
@Qualifier("readDataSource")
private DataSource dataSource;
@Bean
public SqlSessionFactory readSqlSessionFactory() throws Exception{
SqlSessionFactoryBean sqlSessionFactoryBean=new SqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(dataSource);
PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
Resource[] resource=resolver.getResources("classpath:mybatis/read/*.xml");
sqlSessionFactoryBean.setMapperLocations(resource);
return sqlSessionFactoryBean.getObject();
}
@Bean
public SqlSessionTemplate readSqlSession() throws Exception{
SqlSessionTemplate sqlSessionTemplate=new SqlSessionTemplate(readSqlSessionFactory());
return sqlSessionTemplate;
}
}
@Configuration
@MapperScan(basePackages = {"com.zhangfei.dao.write"},sqlSessionFactoryRef = "writeSqlSessionFactory")
public class MyBatisDbBConfig {
@Autowired
@Qualifier("writeDataSource")
private DataSource dataSource;
@Bean
public SqlSessionFactory writeSqlSessionFactory() throws Exception{
SqlSessionFactoryBean sqlSessionFactoryBean=new SqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(dataSource);
PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
Resource[] resource=resolver.getResources("classpath:mybatis/write/*.xml");
sqlSessionFactoryBean.setMapperLocations(resource);
return sqlSessionFactoryBean.getObject();
}
@Bean
public SqlSessionTemplate writeSqlSession() throws Exception{
SqlSessionTemplate sqlSessionTemplate=new SqlSessionTemplate(writeSqlSessionFactory());
return sqlSessionTemplate;
}
}
3、read包下的dao接口
public interface StudentReadDao {
List<Student> getStudentList();
Student getById(long id);
}
4、wite包下的dao接口
public interface StudentWriteDao {
int delete(long id);
int insert(Student student);
int update(Student student);
}
5、分別創建讀寫的mapper文件。我本地分別創建了：resources/mybatis/read/studentdao.xml、/resources/mybatis/write/studentdao.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.zhangfei.dao.read.StudentReadDao">
<select id="getStudentList" resultType="com.zhangfei.entity.Student">
select * from student;
</select>
<select id="getById" resultType="com.zhangfei.entity.Student">
select * from student where id=#{id};
</select>
</mapper>
<?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.zhangfei.dao.write.StudentWriteDao">
<insert id="insert" parameterType="com.zhangfei.entity.Student">
insert into student (name,age) values (#{name},#{age})
</insert>
<update id="update" parameterType="com.zhangfei.entity.Student">
update student set name=#{name},age=#{age} where id=#{id}
</update>
<delete id="delete" parameterType="long">
delete from student where id=#{id}
</delete>
</mapper>
OK。以上幾部就搞定了讀寫分離的准備工作，接着就可以在controller里調用了。 准備工作完成后，還有重要的一點就是需要在程序入口處排除springboot自動屬性提供的數據源 @SpringBootApplication(exclude = DataSourceAutoConfiguration.class)
@RestController
@RequestMapping("/student")
public class StudentController {
@Autowired
StudentReadDao studentDao;
@GetMapping("/getbyid/{id}/")
public Student getById(@PathVariable("id")long id){
Student student=studentDao.getById(id);
return student;
}
@GetMapping("/all/")
public List<Student> getAll(){
return studentDao.getStudentList();
}
}
總結
好了，基本上又是3分鍾就搞定了SpringBoot+MyBatis多數據源或者叫做讀寫分離的工作。那么不知道你又沒有反問我們手動創建的DataSource具體類型是什么呢？ 這里我們在這里只寫了javax.sql.DataSource接口。 我本地用的是springboot 2.0.2 ，當前 DataSourceBuilder 只支持3種類型的數據源： com.zaxxer.hikari.HikariDataSource、org.apache.tomcat.jdbc.pool.DataSource、org.apache.commons.dbcp2.BasicDataSource。可以在DataSourceBuilder類中看到相關代碼。那么現在這種情況因為我們引用的內嵌tomcat，所以我們這里返回的數據源類型是org.apache.tomcat.jdbc.pool.DataSource。 可以用instanceof驗證一下具體的數據源類型。