详解Spring AOP 实现主从读写分离

public class JdbcContextHolder {

 private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>();

 public static void setJdbcType(String jdbcType) {
 contextHolder.set(jdbcType);
 }

 public static void setSlave() {
 setJdbcType("slave");
 }

 public static void setMaster() {
 clearJdbcType();
 }

 public static String getJdbcType() {
 return (String) contextHolder.get();
 }

 public static void clearJdbcType() {
 contextHolder.remove();
 }
}

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

import cn.mayongfa.common.JdbcContextHolder;

public class DynamicDataSource extends AbstractRoutingDataSource {

 @Override
 protected Object determineCurrentLookupKey() {
 // 获取当前数据源连接
 return JdbcContextHolder.getJdbcType();
 }
}

public enum DataSourceType {

 //主库
 Master("master"),

 //从库
 Slave("slave");

 private DataSourceType(String name) {
 this.name = name;
 }

 private String name;

 public String getName() {
 return name;
 }
 public void setName(String name) {
 this.name = name;
 }
}

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME) 
@Target(ElementType.METHOD)
@Documented
public @interface DataSource { 

 DataSourceType value() default DataSourceType.Master;

} 

import java.lang.reflect.Method;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.reflect.MethodSignature;

import cn.mayongfa.common.JdbcContextHolder;

public class DataSourceChoose {

//方法执行前
public void before(JoinPoint point){
 Object target = point.getTarget(); 
 String method = point.getSignature().getName(); 
 Class<?>[] classz = target.getClass().getInterfaces(); 
 MethodSignature methodSignature = (MethodSignature)point.getSignature();
 Class<?>[] parameterTypes = methodSignature.getMethod().getParameterTypes();
 try {
  Method m = classz[0].getMethod(method, parameterTypes); 
  if (m!=null && m.isAnnotationPresent(DataSource.class)) { 
  DataSource data = m.getAnnotation(DataSource.class); 
  JdbcContextHolder.clearJdbcType();
  JdbcContextHolder.setJdbcType(data.value().getName());
  } 
 } catch (Exception e) { 
  // TODO: handle exception 
 } 
}
}