SpringBoot读写分离组件开发详解

环境：springboot2.2.6RELEASE

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实现目标：一写多读，读可以任意配置多个，默认都是从写库中进行操作，只有符合条件的方法（指定的目标方法或者标有指定注解的方法才会从读库中操作）。独立打成一个jar包放入本地仓库。

实现原理：通过aop。

1. pom.xml配置文件

			org.springframework.boot
			spring-boot-starter


			org.springframework.boot
			spring-boot-starter-data-jpa


			org.springframework.boot
			spring-boot-configuration-processor
			true

1. application.yml配置文件

pack:
  datasource:
    pointcut: execution(public * net.greatsoft.service.base.*.*(..)) || execution(public * net.greatsoft.service.xxx.*.*(..))
    master:
      driverClassName: oracle.jdbc.driver.OracleDriver
      jdbcUrl: jdbc:oracle:thin:@10.100.102.113:1521/orcl
      username: test
      password: test
      minimumIdle: 10
      maximumPoolSize: 200
      autoCommit: true
      idleTimeout: 30000
      poolName: MbookHikariCP
      maxLifetime: 1800000
      connectionTimeout: 30000
      connectionTestQuery: SELECT 1 FROM DUAL  
    slaves:
      - driverClassName: oracle.jdbc.driver.OracleDriver
        jdbcUrl: jdbc:oracle:thin:@10.100.102.113:1521/orcl
        username: dc
        password: dc
        minimumIdle: 10
        maximumPoolSize: 200
        autoCommit: true
        idleTimeout: 30000
        poolName: MbookHikariCP
        maxLifetime: 1800000
        connectionTimeout: 30000
        connectionTestQuery: SELECT 1 FROM DUAL
      - driverClassName: oracle.jdbc.driver.OracleDriver
        jdbcUrl: jdbc:oracle:thin:@10.100.102.113:1521/orcl
        username: empi
        password: empi
        minimumIdle: 10
        maximumPoolSize: 200
        autoCommit: true
        idleTimeout: 30000
        poolName: MbookHikariCP
        maxLifetime: 1800000
        connectionTimeout: 30000
        connectionTestQuery: SELECT 1 FROM DUAL

pointcut：定义切点，那些方法是需要拦截（从读库中操作）。

master：写库配置。

slaves：读库配置（List集合）。

1. 属性配置类

@Component
@ConfigurationProperties(prefix = "pack.datasource")
public class RWDataSourceProperties {
	
	private String pointcut ;
	private HikariConfig master ;
	private List slaves = new ArrayList<>();
	
}

1. 读写配置类

public class RWConfig  {
	
	private static Logger logger = LoggerFactory.getLogger(RWConfig.class) ;

	@Bean
	public HikariDataSource masterDataSource(RWDataSourceProperties rwDataSourceProperties) {
		return new HikariDataSource(rwDataSourceProperties.getMaster()) ;
	}
	
	@Bean
	public List slaveDataSources(RWDataSourceProperties rwDataSourceProperties) {
		List lists = new ArrayList<>() ;
		for(HikariConfig config : rwDataSourceProperties.getSlaves()) {
			lists.add(new HikariDataSource(config)) ;
		}
		return lists ;
	}
	
	@Bean
  @Primary
	@DependsOn({"masterDataSource", "slaveDataSources"})
	public AbstractRoutingDataSource routingDataSource(@Qualifier("masterDataSource")DataSource masterDataSource,
			@Qualifier("slaveDataSources")List slaveDataSources) {
		BaseRoutingDataSource ds = new BaseRoutingDataSource() ;
		Map targetDataSources = new HashMap<>(2) ;
		targetDataSources.put("master", masterDataSource) ;
		for (int i = 0; i < slaveDataSources.size(); i++) {
			targetDataSources.put("slave-" + i, slaveDataSources.get(i)) ;
		}
		ds.setDefaultTargetDataSource(masterDataSource) ;
		ds.setTargetDataSources(targetDataSources) ;
		return ds ;
	}
	
}

1. 数据源路由

public class BaseRoutingDataSource extends AbstractRoutingDataSource {

	@Resource
	private DataSourceHolder holder;
	
	@Override
	protected Object determineCurrentLookupKey() {
		return holder.get() ;
	}
	
}

public class DataSourceHolder {
	
	private ThreadLocal context = new ThreadLocal() {
		@Override
		protected Integer initialValue() {
			return 0 ;
		}
	};
	
	@Resource
	private BaseSlaveLoad slaveLoad ;
	
	public String get() {
		Integer type = context.get() ;
		return type == null || type == 0 ? "master" : "slave-" + slaveLoad.load() ;
	}
	
	public void set(Integer type) {
		context.set(type) ;
	}
	
}

通过aop动态设置context的内容值，0为从写库中操作，其它的都在读库中操作。

BaseSlaveLoad类为到底从那个读库中选取的一个算法类，默认实现使用的是轮询算法。

public interface BaseSlaveLoad {

	int load() ;
	
}

public abstract class AbstractSlaveLoad implements BaseSlaveLoad {

	@Resource
	protected List slaveDataSources ;
	
}

这里定义一个抽象类注入了读库列表，所有的实现类从该类中继承即可。

public class PollingLoad extends AbstractSlaveLoad {
	
	private int index = 0 ;
	private int size = 1 ;
	
	@PostConstruct
	public void init() {
		size = slaveDataSources.size() ;
	}
	
	@Override
	public int load() {
		int n = index ;
		synchronized (this) {
			index = (++index) % size ;
		}
		return n ;
	}
	
}

配置成Bean

@Bean
	@ConditionalOnMissingBean
	public BaseSlaveLoad slaveLoad() {
		return new PollingLoad() ;
	}
	
	@Bean
	public DataSourceHolder dataSourceHolder() {
		return new DataSourceHolder() ;
	}

1. 数据源AOP

public class DataSourceAspect implements MethodInterceptor {

	private DataSourceHolder holder ;
	
	public DataSourceAspect(DataSourceHolder holder) {
		this.holder = holder ;
	}
	
	@Override
	public Object invoke(MethodInvocation invocation) throws Throwable {
		Method method = invocation.getMethod() ;
		String methodName = method.getName() ;
		SlaveDB slaveDB = method.getAnnotation(SlaveDB.class) ;
		if (slaveDB == null) {
			slaveDB = method.getDeclaringClass().getAnnotation(SlaveDB.class) ;
		}
		if (methodName.startsWith("find") 
				|| methodName.startsWith("get")
				|| methodName.startsWith("query")
				|| methodName.startsWith("select")
				|| methodName.startsWith("list")
				|| slaveDB != null) {
			holder.set(1) ;
		} else {
			holder.set(0) ;
		}
		return invocation.proceed();
	}

}

应该切点需要动态配置，所以这里采用spring aop的方式来配置

@Bean
	public AspectJExpressionPointcutAdvisor logAdvisor(RWDataSourceProperties props, DataSourceHolder holder) {
		AspectJExpressionPointcutAdvisor advisor = new AspectJExpressionPointcutAdvisor() ;
		logger.info("执行表达式：{}", props.getPointcut()) ;
		advisor.setExpression(props.getPointcut()) ;
		advisor.setAdvice(new DataSourceAspect(holder)) ;
		return advisor ;
	}

1. Enable开启功能

public class RWImportSelector implements ImportSelector {

	@Override
	public String[] selectImports(AnnotationMetadata importingClassMetadata) {
		return new String[] {RWConfig.class.getName()} ;
	}

}

这里的RWConfig为我们上面的配置类

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Import({RWImportSelector.class})
public @interface EnableRW {
}

@Documented
@Retention(RUNTIME)
@Target({ TYPE, METHOD })
public @interface SlaveDB {
}

有@SlaveDB的注解方法会类都会从读库中操作。

到此读写分离组件开发完成。

1. 打包安装到本地仓库

mvn install -Dmaven.test.skip=true

1. 新建base-web项目

引入依赖

			com.pack
			xg-component-rw
			1.0.0

启动类添加注解开启读写分离功能

@SpringBootApplication
@EnableRW
public class BaseWebApplication {

	public static void main(String[] args) {
		SpringApplication.run(BaseWebApplication.class, args);
	}

}

测试：

第一次查询：

 

第二次查询：

 

为了区别两个从库设置不同的数据

这里是写库

完毕！！！

给个转发+关注呗谢谢

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