sprint boot 读写分离

思路：

如何切换？

1、利用覆盖实现 AbstractRoutingDataSource.determineCurrentLookupKey 返回当前所需的数据源名称，已达到动态切换数据源。

为了线程安全，将determineCurrentLookupKey 返回值定义为ThreadLocal。

什么时候切换？

1、利用spring aop 根据当前方法名切换数据源。

AbstractRoutingDataSource实现：

/**
 * 
 * @Description: TODO( spring 通过determineCurrentLookupKey获取数据源名称，
 * 所以动态修改 determineCurrentLookupKey返回值，即可达到切换数据源)
 * @author: chenwm
 * @date:   2017年6月8日 上午9:41:39 
 *
 */
public class ChooseDataSource extends AbstractRoutingDataSource {
	// 获取数据源名称
	protected Object determineCurrentLookupKey() {
		return HandleDataSource.getDataSource();
	}
}

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HandleDataSource实现：

/**
 * 
 * @Description: TODO( 保证数据源线程安全 )
 * @author: chenwm
 * @date:   2017年6月8日 上午9:33:57 
 *
 */
public class HandleDataSource {
	// 数据源名称线程池
	private static final ThreadLocal<String> holder = new ThreadLocal<String>();

	public static void putDataSource(String datasource) {
		holder.set(datasource);
	}

	public static String getDataSource() {
		return holder.get();
	}

	public static void clear() {
		holder.remove();
	}
}

定义切入点：

/**
 * 
 * @Description: TODO( aop切换数据源 )
 * @author: chenwm
 * @date:   2017年6月8日 上午9:33:33 
 *
 */
@Aspect
@Order(-10)//保证该AOP在@Transactional之前执行
@Component
public class DataSourceAspect {

	public static String slaveDSName  = "slaveDataSource";
	public static String masterDSName = "masterDataSource";
	public static String[] slaveReg = new String[]{"get","select","count","list","query","find"};
	public static String[] masterReg    = new String[]{"add","insert","create","update","delete","remove"};
	
	public boolean isMaster(String methodName){
		return StringUtils.startsWithAny(methodName,masterReg);
	}
	
	public boolean isSlave(String methodName){
		return StringUtils.startsWithAny(methodName,slaveReg);
	}
	
	@Pointcut("execution(* org.quickjee.service..*.*(..))")
	public void aspect() {
	}

	/**
	 * 
	 * @Description: TODO( 配置前置通知,使用在方法aspect()上注册的切入点 )   
	 * @param: @param point      
	 * @return: void      
	 * @throws
	 */
	@Before("aspect()")
	public void before(JoinPoint point) {
		String className = point.getTarget().getClass().getName();
		String method = point.getSignature().getName();
		System.out.println(className + "." + method + "(" + StringUtils.join(point.getArgs(), ",") + ")");
		try {
			if(isMaster(method)){//主库
				HandleDataSource.putDataSource(DataSourceAspect.masterDSName);
			}else if(isSlave(method)){//从库
				HandleDataSource.putDataSource(DataSourceAspect.slaveDSName);
			}else{
				HandleDataSource.putDataSource(DataSourceAspect.masterDSName);
			}
		} catch (Exception e) {
			HandleDataSource.putDataSource(DataSourceAspect.masterDSName);
		}
	}

	/**
	 * 
	 * @Description: TODO( 清除当前数据源 )   
	 * @param: @param point      
	 * @return: void      
	 * @throws
	 */
	@After("aspect()")
	public void after(JoinPoint point) {
		HandleDataSource.clear();
	}
}

定义数据源：

public class DynamicDataSourceRegister implements
		ImportBeanDefinitionRegistrar, EnvironmentAware {

	private DataSource masterDataSource;//主库
	private DataSource slaveDataSource;//从库
	private Map<String, DataSource> targetDataSources = new HashMap<String, DataSource>();

	private void initTargetDataSources(DBProperties dbParams) {
		slaveDataSource  = buildDataSources(dbParams,true);//初始化
		masterDataSource = buildDataSources(dbParams,false);
		targetDataSources.put(DataSourceAspect.slaveDSName, slaveDataSource);
		targetDataSources.put(DataSourceAspect.masterDSName, masterDataSource);
	}

	private DataSource buildDataSources(DBProperties dbProperties,boolean readOnly) {
		DruidDataSource dataSource = new DruidDataSource();
		List<Filter> filters = new ArrayList<Filter>();
		dataSource.setDriverClassName(dbProperties.getDriverClassName());
		dataSource.setUrl(dbProperties.getUrl());
		dataSource.setUsername(dbProperties.getUsername());
		dataSource.setPassword(dbProperties.getPassword());
		dataSource.setInitialSize(dbProperties.getInitialSize());
		dataSource.setMaxActive(dbProperties.getMaxActive());
		dataSource.setMinIdle(dbProperties.getMaxIdle());
		dataSource.setDefaultReadOnly(readOnly);//只读
		//dataSource.setProxyFilters(filters);
		dataSource.setTestWhileIdle(true);
		dataSource.setTestOnBorrow(false);
		dataSource.setTestOnReturn(false);
		dataSource.setValidationQuery("SELECT 'x'");
		dataSource.setTimeBetweenLogStatsMillis(dbProperties.getTimeBetweenLogStatsMillis());
		dataSource.setTimeBetweenEvictionRunsMillis(dbProperties.getTimeBetweenEvictionRunsMillis());
		dataSource.setMinEvictableIdleTimeMillis(dbProperties.getMinEvictableIdleTimeMillis());
		return dataSource;
	}

	@Override
	public void setEnvironment(Environment env) {
		DBProperties dbParams = getDBParams(new RelaxedPropertyResolver(
				env, "db."));
		initTargetDataSources(dbParams);
	}

	private DBProperties getDBParams(RelaxedPropertyResolver resolver) {
		DBProperties db = new DBProperties();
		db.setDriverClassName(resolver.getProperty("driverClassName"));
		db.setInitialSize(Integer.parseInt(resolver.getProperty("initialSize")));
		db.setMaxActive(Integer.parseInt(resolver.getProperty("maxActive")));
		db.setMaxIdle(Integer.parseInt(resolver.getProperty("maxIdle")));
		db.setMaxPoolPreparedStatementPerConnectionSize(Integer.parseInt(resolver
				.getProperty("maxPoolPreparedStatementPerConnectionSize")));
		db.setUrl(resolver.getProperty("url"));
		db.setUsername(resolver.getProperty("username"));
		db.setPassword(resolver.getProperty("password"));
		db.setMinIdle(Integer.parseInt(resolver.getProperty("minIdle")));
		db.setMaxWait(Integer.parseInt(resolver.getProperty("maxWait")));
		db.setTimeBetweenLogStatsMillis(Integer.parseInt(resolver
				.getProperty("timeBetweenLogStatsMillis")));
		db.setTimeBetweenEvictionRunsMillis(Integer.parseInt(resolver
				.getProperty("timeBetweenEvictionRunsMillis")));
		db.setMinEvictableIdleTimeMillis(Integer.parseInt(resolver
				.getProperty("minEvictableIdleTimeMillis")));
		return db;
	}

	/**
	 * 往spring注册bean
	 * <p>Title: registerBeanDefinitions</p>   
	 * <p>Description: </p>   
	 * @param importingClassMetadata
	 * @param registry   
	 * @see org.springframework.context.annotation.ImportBeanDefinitionRegistrar#registerBeanDefinitions(org.springframework.core.type.AnnotationMetadata, org.springframework.beans.factory.support.BeanDefinitionRegistry)
	 */
	@Override
	public void registerBeanDefinitions(
			AnnotationMetadata importingClassMetadata,
			BeanDefinitionRegistry registry) {
		// 创建ChooseDataSource
        GenericBeanDefinition beanDefinition = new GenericBeanDefinition();
        beanDefinition.setBeanClass(ChooseDataSource.class);
        beanDefinition.setSynthetic(true);
        MutablePropertyValues mpv = beanDefinition.getPropertyValues();
        //添加属性：AbstractRoutingDataSource.defaultTargetDataSource
        mpv.addPropertyValue("defaultTargetDataSource", masterDataSource);
        mpv.addPropertyValue("targetDataSources", targetDataSources);
        registry.registerBeanDefinition("dataSource", beanDefinition);
	}

}

本切入点org.quickjee.service..*.*(..) ，即service层，

测试demo:

@Service
public class UserService {
	
    @Resource
    private UserRepository userRepository;
            
    public SysUser findById(long id) {      
       return userRepository.findOne(id);
    }
    
    @Transactional
    public SysUser update(long id) {
    	SysUser user = userRepository.findOne(id);
        user.setPhone("13900139000");
        userRepository.save(user);
        return user;
     }   

}

Controller:

@RestController
public class TestController {
	
	@Autowired
	private UserService userService;
	
	@RequestMapping("/index")
	public String index(){
	SysUser loaded = userService.findById(1L);
	SysUser cached = userService.update(1L);
        //loaded = userService.findById(2);
        return"ok";
	}
		
}

sprint boot 读写分离

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