Spring Boot 集成Mybatis实现主从(多数据源)分离方案示例
本文将介绍使用Spring Boot集成Mybatis并实现主从库分离的实现(同样适用于多数据源)。延续之前的Spring Boot 集成MyBatis。项目还将集成分页插件PageHelper、通用Mapper以及Druid。 新建一个Maven项目,最终项目结构如下: 多数据源注入到sqlSessionFactory POM增加如下依赖: <!--JSON--> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> </dependency> <dependency> <groupId>com.fasterxml.jackson.datatype</groupId> <artifactId>jackson-datatype-joda</artifactId> </dependency> <dependency> <groupId>com.fasterxml.jackson.module</groupId> <artifactId>jackson-module-parameter-names</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>1.0.11</version> </dependency> <!--mybatis--> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>1.1.1</version> </dependency> <!--mapper--> <dependency> <groupId>tk.mybatis</groupId> <artifactId>mapper-spring-boot-starter</artifactId> <version>1.1.0</version> </dependency> <!--pagehelper--> <dependency> <groupId>com.github.pagehelper</groupId> <artifactId>pagehelper-spring-boot-starter</artifactId> <version>1.1.0</version> <exclusions> <exclusion> <artifactId>mybatis-spring-boot-starter</artifactId> <groupId>org.mybatis.spring.boot</groupId> </exclusion> </exclusions> </dependency> 这里需要注意的是:项目是通过扩展mybatis-spring-boot-starter的org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration来实现多数据源注入的。在mybatis-spring-boot-starter:1.2.0中,该类取消了默认构造函数,因此本项目依旧使用1.1.0版本。需要关注后续版本是否会重新把扩展开放处理。 之所以依旧使用旧方案,是我个人认为开放扩展是合理的,相信在未来的版本中会回归。 如果你需要其他方案可参考传送门 增加主从库配置(application.yml) druid: type: com.alibaba.druid.pool.DruidDataSource master: url: jdbc:mysql://192.168.249.128:3307/db-test?characterEncoding=UTF-8&autoReconnect=true&zeroDateTimeBehavior=convertToNull&useUnicode=true driver-class-name: com.mysql.jdbc.Driver username: root password: root initial-size: 5 min-idle: 1 max-active: 100 test-on-borrow: true slave: url: jdbc:mysql://192.168.249.128:3317/db-test?characterEncoding=UTF-8&autoReconnect=true&zeroDateTimeBehavior=convertToNull&useUnicode=true&characterEncoding=utf-8 driver-class-name: com.mysql.jdbc.Driver username: root password: root initial-size: 5 min-idle: 1 max-active: 100 test-on-borrow: true 创建数据源 @Configuration @EnableTransactionManagement public class DataSourceConfiguration { @Value("${druid.type}") private Class<? extends DataSource> dataSourceType; @Bean(name = "masterDataSource") @Primary @ConfigurationProperties(prefix = "druid.master") public DataSource masterDataSource(){ return DataSourceBuilder.create().type(dataSourceType).build(); } @Bean(name = "slaveDataSource") @ConfigurationProperties(prefix = "druid.slave") public DataSource slaveDataSource1(){ return DataSourceBuilder.create().type(dataSourceType).build(); } } 将多数据源注入到sqlSessionFactory中 前面提到了这里通过扩展mybatis-spring-boot-starter的org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration来实现多数据源注入的 @Configuration @AutoConfigureAfter({DataSourceConfiguration.class}) public class MybatisConfiguration extends MybatisAutoConfiguration { private static Log logger = LogFactory.getLog(MybatisConfiguration.class); @Resource(name = "masterDataSource") private DataSource masterDataSource; @Resource(name = "slaveDataSource") private DataSource slaveDataSource; @Bean public SqlSessionFactory sqlSessionFactory() throws Exception { return super.sqlSessionFactory(roundRobinDataSouceProxy()); } public AbstractRoutingDataSource roundRobinDataSouceProxy(){ ReadWriteSplitRoutingDataSource proxy = new ReadWriteSplitRoutingDataSource(); Map<Object,Object> targetDataResources = new ClassLoaderRepository.SoftHashMap(); targetDataResources.put(DbContextHolder.DbType.MASTER,masterDataSource); targetDataResources.put(DbContextHolder.DbType.SLAVE,slaveDataSource); proxy.setDefaultTargetDataSource(masterDataSource);//默认源 proxy.setTargetDataSources(targetDataResources); return proxy; } } 实现读写分离(多数据源分离) 这里主要思路如下: 1-将不同的数据源标识记录在ThreadLocal中 2-通过注解标识出当前的service方法使用哪个库 3-通过Spring AOP实现拦截注解并注入不同的标识到threadlocal中 4-获取源的时候通过threadlocal中不同的标识给出不同的sqlSession 标识存放ThreadLocal的实现 public class DbContextHolder { public enum DbType{ MASTER,SLAVE } private static final ThreadLocal<DbType> contextHolder = new ThreadLocal<>(); public static void setDbType(DbType dbType){ if(dbType==null)throw new NullPointerException(); contextHolder.set(dbType); } public static DbType getDbType(){ return contextHolder.get()==null?DbType.MASTER:contextHolder.get(); } public static void clearDbType(){ contextHolder.remove(); } } 注解实现 /** * 该注解注释在service方法上,标注为链接slaves库 * Created by Jason on 2017/3/6. */ @Target({ElementType.METHOD,ElementType.TYPE}) @Retention(RetentionPolicy.RUNTIME) public @interface ReadOnlyConnection { } Spring AOP对注解的拦截 @Aspect @Component public class ReadOnlyConnectionInterceptor implements Ordered { public static final Logger logger = LoggerFactory.getLogger(ReadOnlyConnectionInterceptor.class); @Around("@annotation(readOnlyConnection)") public Object proceed(ProceedingJoinPoint proceedingJoinPoint,ReadOnlyConnection readOnlyConnection) throws Throwable { try { logger.info("set database connection to read only"); DbContextHolder.setDbType(DbContextHolder.DbType.SLAVE); Object result = proceedingJoinPoint.proceed(); return result; }finally { DbContextHolder.clearDbType(); logger.info("restore database connection"); } } @Override public int getOrder() { return 0; } } 根据标识获取不同源 这里我们通过扩展AbstractRoutingDataSource来获取不同的源。它是Spring提供的一个可以根据用户发起的不同请求去转换不同的数据源,比如根据用户的不同地区语言选择不同的数据库。通过查看源码可以发现,它是通过determineCurrentLookupKey()返回的不同key到sqlSessionFactory中获取不同源(前面已经展示了如何在sqlSessionFactory中注入多个源) public class ReadWriteSplitRoutingDataSource extends AbstractRoutingDataSource { @Override protected Object determineCurrentLookupKey() { return DbContextHolder.getDbType(); } } 以上就完成了读写分离(多数据源)的配置方案。下面是一个具体的实例 使用方式 Entity @Table(name = "t_sys_dic_type") public class DicType extends BaseEntity{ String code; String name; Integer status; ... } Mapper public interface DicTypeMapper extends BaseMapper<DicType> { } Service @Service public class DicTypeService { @Autowired private DicTypeMapper dicTypeMapper; @ReadOnlyConnection public List<DicType> getAll(DicType dicType){ if (dicType.getPage() != null && dicType.getRows() != null) { PageHelper.startPage(dicType.getPage(),dicType.getRows()); } return dicTypeMapper.selectAll(); } } 注意这里的@ReadOnlyConnection注解 Controller @RestController @RequestMapping("/dictype") public class DicTypeController { @Autowired private DicTypeService dicTypeService; @RequestMapping(value = "/all") public PageInfo<DicType> getALL(DicType dicType){ List<DicType> dicTypeList = dicTypeService.getAll(dicType); return new PageInfo<>(dicTypeList); } } 通过mvn spring-boot:run启动后,即可通过http://localhost:9090/dictype/all 获取到数据 后台打印出 c.a.d.m.ReadOnlyConnectionInterceptor : set database connection to read only 说明使用了从库的链接获取数据 备注:如何保证多源事务呢? 1-在读写分离场景中不会考虑主从库事务,在纯读的上下文上使用@ReadOnlyConnection标签。其他则默认使用主库。 2-在多源场景中,Spring的@Transaction是可以保证多源的事务性的。 本文使用代码 以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持编程小技巧。 您可能感兴趣的文章:
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