SpringBoot读写分离组件开发详解-51CTO.COM

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。

pom.xml配置文件

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-configuration-processor</artifactId>
  <optional>true</optional>
</dependency>

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）。

属性配置类

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

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<HikariDataSource> slaveDataSources(RWDataSourceProperties rwDataSourceProperties) {
    List<HikariDataSource> 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<HikariDataSource> slaveDataSources) {
    BaseRoutingDataSource ds = new BaseRoutingDataSource() ;
    Map<Object, Object> 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 ;
  }
  
}

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<Integer> context = new ThreadLocal<Integer>() {
    @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<HikariDataSource> 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() ;
}

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 ;
}

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的注解方法或类都会从读库中操作。

到此读写分离组件开发完成。

打包安装到本地仓库

mvn install -Dmaven.test.skip=true

新建base-web项目

引入依赖

<dependency>
  <groupId>com.pack</groupId>
  <artifactId>xg-component-rw</artifactId>
  <version>1.0.0</version>
</dependency>

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：

图片

第二次查询：

图片

为了区别两个从库设置不同的数据

这里是写库