这篇文章主要介绍springboot结合mysql主从来实现读写分离的方法,文中介绍的非常详细,具有一定的参考价值,感兴趣的小伙伴们一定要看完!
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。
application.properties中的配置
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
@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
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
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。
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
@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:
@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,
@DataSource(DBTypeEnum.SLAVE)
然后AOP方法修改为:
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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