1.实现的功能
基于springboot框架，application.yml配置多个数据源，使用AOP以及AbstractRootingDataSource、ThreadLocal来实现多数据源切换，以实现读写分离。mysql的主从数据库需要进行设置数据之间的同步。
2.代码实现
application.properties中的配置
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spring.datasource.druid.master.driver-class-name=com.mysql.jdbc.Driver spring.datasource.druid.master.url=jdbc:mysql://127.0.0.1:3306/node2?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true&autoReconnect=true&useSSL=false spring.datasource.druid.master.username=root spring.datasource.druid.master.password=123456
spring.datasource.druid.slave.driver-class-name=com.mysql.jdbc.Driver spring.datasource.druid.slave.url=jdbc:mysql://127.0.0.1:3306/node1?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true&autoReconnect=true&useSSL=false spring.datasource.druid.slave.username=root spring.datasource.druid.slave.password=123456 |
写一个DataSourceConfig.java来注入两个bean
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@Bean @ConfigurationProperties ( "spring.datasource.druid.master" ) public DataSource masterDataSource() { logger.info( "select master data source" ); return DruidDataSourceBuilder.create().build(); }
@Bean @ConfigurationProperties ( "spring.datasource.druid.slave" ) public DataSource slaveDataSource() { logger.info( "select slave data source" ); return DruidDataSourceBuilder.create().build(); } |
写一个enum来标识有哪些数据源
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public enum DBTypeEnum { MASTER, SLAVE; } |
然后写一个ThreadLocal本地线程的管理类,用于设置当前线程是那一个数据源
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private static final ThreadLocal<DBTypeEnum> contextHolder = new ThreadLocal<>();
private static final ThreadLocal<DBTypeEnum> contextHolder2 = ThreadLocal.withInitial(() -> DBTypeEnum.MASTER);
public static void set(DBTypeEnum dbType) { contextHolder.set(dbType); }
public static DBTypeEnum get() { return contextHolder.get(); }
public static void master() { set(DBTypeEnum.MASTER); logger.info( "切换到master数据源" ); }
public static void slave() { set(DBTypeEnum.SLAVE); logger.info( "切换到slave数据源" ); }
public static void cleanAll() { contextHolder.remove(); } |
然后写一个DynamicDataSource继承AbstractRootingDataSource,重写它的determineCurrentLookupKey方法。
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public class DynamicDataSource extends AbstractRoutingDataSource { private Logger logger = LogManager.getLogger(DynamicDataSource. class );
@Override protected Object determineCurrentLookupKey() { logger.info( "此时数据源为{}" , DBContextHolder.get()); return DBContextHolder.get(); } } |
最后写一个AOP来实现数据源切换
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@Aspect @Order ( 1 ) @Component public class DataSourceAop {
private Logger logger = LogManager.getLogger(DataSourceAop. class );
@Pointcut ( "(execution(* com.springboot.demo.service..*.select*(..)) " + "|| execution(* com.springboot.demo.service..*.find*(..)) " + "|| execution(* com.springboot.demo.service..*.get*(..)))" ) public void readPointcut() { logger.info( "read only operate ,into slave db" ); }
@Pointcut ( "execution(* com.springboot.demo.service..*.insert*(..)) " + "|| execution(* com.springboot.demo.service..*.update*(..)) " + "|| execution(* com.springboot.demo.service..*.delete*(..)) " ) public void writePointcut() { logger.info( "read or write operate ,into master db" ); }
@Before ( "readPointcut()" ) public void read() { logger.info( "read operate" ); DBContextHolder.slave(); }
@Before ( "writePointcut()" ) public void write() { logger.info( "write operate" ); DBContextHolder.master(); }
@After ( "writePointcut(),readPointcut()" ) public void clean() { logger.info( "dataSource cleanAll" ); DBContextHolder.cleanAll(); } } |
注意：这里只是使用了偷懒的方法，对于service里面的select、get、find前缀的方法都使用从库，对于insert、update和delete方法都使用主库。
可以使用注解如下来进行优化:
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@Retention (RetentionPolicy.RUNTIME) @Target (ElementType.METHOD) public @interface DataSource {
@AliasFor ( "dataSource" ) DBTypeEnum value() default DBTypeEnum.MASTER;
DBTypeEnum dataSource() default DBTypeEnum.MASTER;
} |
使用此注解来放入到service方法上，
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@DataSource (DBTypeEnum.SLAVE) |
然后AOP方法修改为：
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private static final String POINT = "execution (* com.springboot.demo.service.*.*(..))" ;
@Around (POINT) public Object dataSourceAround(ProceedingJoinPoint joinPoint) throws Throwable { Object[] args = joinPoint.getArgs(); Object obj; Object target = joinPoint.getTarget(); String methodName = joinPoint.getSignature().getName(); Class clazz = target.getClass(); Class<?>[] parameterTypes = ((MethodSignature) joinPoint.getSignature()).getMethod().getParameterTypes(); boolean isDynamicDataSourceMethod = false ; try { Method method = clazz.getMethod(methodName, parameterTypes); DataSources currentDataSource = null ; if (method != null && method.isAnnotationPresent(DataSource. class )) { isDynamicDataSourceMethod = true ; currentDataSource = method.getAnnotation(DataSource. class ).value(); DataSourceTypeManager.set(currentDataSource); log.info( "DataSourceInterceptor Switch DataSource To {}" ,currentDataSource); } obj = joinPoint.proceed(args); if (isDynamicDataSourceMethod) { log.info( "DataSourceInterceptor DataSource {} proceed" ,currentDataSource); } } finally { if (isDynamicDataSourceMethod) { DataSourceTypeManager.reset(); log.info( "DataSourceInterceptor Reset DataSource To {}" ,DataSourceTypeManager.get()); } } return obj; } |
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原文链接：https://blog.csdn.net/yancun93/article/details/103958645
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