SpringBoot中如何实现一个读写分离组件

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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 

2.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)。

3.属性配置类

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

4.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 ;     }      }

5.数据源路由

1. public class BaseRoutingDataSource extends AbstractRoutingDataSource {

2. @Resource

3. private DataSourceHolder holder;

4. @Override

5. protected Object determineCurrentLookupKey() {

6. return holder.get() ;

7. }

8. }

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。

1. public interface BaseSlaveLoad {

2. int load() ;

3. }

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() ;     }

6.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.set_Expression(props.getPointcut()) ;         advisor.setAdvice(new DataSourceAspect(holder)) ;         return advisor ;     }

7.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

1. @Retention(RetentionPolicy.RUNTIME)

2. @Target(ElementType.TYPE)

3. @Documented

4. @Import({RWImportSelector.class})

5. public @interface EnableRW {

6. }

@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。

8.打包安装到本地仓库

mvn install -Dmaven.test.skip=true

9.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

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