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spring boot(四) 多数据源

前言

        前一篇中我们使用spring boot+mybatis创建了单一数据源,其中单一数据源不需要我们自己手动创建,spring boot自动配置在程序启动时会替我们创建好数据源。

准备工作

       application.yml中配置connection的4个属性

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

  

多数据源创建方法

      1、多数据源主要是需要我们手动来创建DataSource、SqlSessionFactory、SqlSessionTemplate。这里我们基于同一个库来创建读写分离的数据源。这里两个方法的返回值都是javax.sql.DataSource。

   

@Configurationpublic 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、读写分离的配置类。也就是分别创建读写的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、分别创建读写的mapper文件。我本地分别创建了: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。以上几部就搞定了读写分离的准备工作,接着就可以在controller里调用了。 准备工作完成后,还有重要的一点就是需要在程序入口处排除springboot自动属性提供的数据源  @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(); }}

  

 

总结

       好了,基本上又是3分钟就搞定了SpringBoot+MyBatis多数据源或者叫做读写分离的工作。那么不知道你又没有反问我们手动创建的DataSource具体类型是什么呢? 这里我们在这里只写了javax.sql.DataSource接口。 我本地用的是springboot 2.0.2 ,当前 DataSourceBuilder 只支持3种类型的数据源: com.zaxxer.hikari.HikariDataSource、org.apache.tomcat.jdbc.pool.DataSource、org.apache.commons.dbcp2.BasicDataSource。可以在DataSourceBuilder类中看到相关代码。那么现在这种情况因为我们引用的内嵌tomcat,所以我们这里返回的数据源类型是org.apache.tomcat.jdbc.pool.DataSource。 可以用instanceof测试一下具体的数据源类型。

 

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