理解spring动态切换数据源，需要对spring具有一定的了解
工作中经常遇到读写分离，数据源切换的问题，那么以下是本作者实际工作中编写的代码 与大家分享一下！
1.定义注解 DataSource
package com.gomecar.index.datasource; import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target; /**
* 数据源切换注解
* @author xiaotian
*
*/
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE,ElementType.METHOD})
public @interface DataSource { String value() default "read"; }
2. 定义切面DataSourceAspect
package com.gomecar.index.datasource; import java.lang.reflect.Method;
import org.apache.log4j.Logger;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.reflect.MethodSignature; /**
* 用于数据库读写分离的切面
* @author xiaotian
*
*/
@Aspect
public class DataSourceAspect { //日志
private Logger logger = Logger.getLogger(this.getClass()); /**
* 拦截目标方法，获取由@DataSource指定的数据源标识，设置到线程存储中以便切换数据源
*
* @param point
* @throws Exception
*/
public void intercept(JoinPoint point) throws Exception {
Class<?> target = point.getTarget().getClass();
MethodSignature signature = (MethodSignature) point.getSignature();
for (Class<?> clazz : target.getInterfaces()) {
resolveDataSource(clazz, signature.getMethod());
}
resolveDataSource(target, signature.getMethod());
} /**
* 提取目标对象方法注解和类型注解中的数据源标识
*
* @param clazz
* @param method
*/
private void resolveDataSource(Class<?> clazz, Method method) {
try {
Class<?>[] types = method.getParameterTypes();
// 默认使用类型注解dataSourcePointcutdataSourcePointcut
if (clazz.isAnnotationPresent(DataSource.class)) {
DataSource source = clazz.getAnnotation(DataSource.class);
DynamicDataSourceHolder.putDataSource(source.value());
}
// 方法注解可以覆盖类型注解
Method m = clazz.getMethod(method.getName(), types);
if (m != null && m.isAnnotationPresent(DataSource.class)) {
DataSource source = m.getAnnotation(DataSource.class);
DynamicDataSourceHolder.putDataSource(source.value());
}
} catch (Exception e) {
logger.error("切换数据源error", e);
}
} //通知
public void before(JoinPoint point)
{
Object target = point.getTarget();
String method = point.getSignature().getName();
//反射获取接口
Class<?>[] classz = target.getClass().getInterfaces();
//获取返回值类型
Class<?>[] parameterTypes = ((MethodSignature) point.getSignature())
.getMethod().getParameterTypes();
try {
//获取方法
Method m = classz[0].getMethod(method, parameterTypes);
//根据方法上注解 获取只读数据库连接池 或者只写数据库连接池
if (m != null && m.isAnnotationPresent(DataSource.class)) {
//根据注解值获取数据库连接池
DataSource data = m
.getAnnotation(DataSource.class);
DynamicDataSourceHolder.putDataSource(data.value());
System.out.println(data.value());
} } catch (Exception e) {
// TODO: handle exception
}
}
}
3.获取动态数据源DynamicDataSource
package com.gomecar.index.datasource; import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
/**
* 动态获取数据源
* @author xiaotian
*
*/
public class DynamicDataSource extends AbstractRoutingDataSource { @Override
protected Object determineCurrentLookupKey() {
return DynamicDataSourceHolder.getDataSouce();
} }
4.数据源持有者DynamicDataSourceHolder
package com.gomecar.index.datasource;
/**
* 数据库连接池 持有者
* 将数据库连接绑定到当前线程
* @author xiaotian
*
*/
public class DynamicDataSourceHolder {
//绑定当前线程
public static final ThreadLocal<String> holder = new ThreadLocal<String>();
//设置数据源
public static void putDataSource(String name) {
holder.set(name);
}
//获取数据源
public static String getDataSouce() {
return holder.get();
}
}