静态代理示例实现动态分库功能示例
1、代码结构如下图： 
2、创建订单和用户类
package com.rf.designPatterns.structural.proxy;
/**
* @description: 订单和用户类
* @author: xz
*/
public class Order {
private Object orderId;//订单id
private Integer userId;//用户id
public Object getOrderId() {
return orderId;
}
public void setOrderId(Object orderId) {
this.orderId = orderId;
}
public Integer getUserId() {
return userId;
}
public void setUserId(Integer userId) {
this.userId = userId;
}
}
3、创建Service层
package com.rf.designPatterns.structural.proxy;
/**
* @description: Service层
* @author: xz
*/
public interface OrderService {
int saveOrder(Order order);
}
4、创建Dao层
package com.rf.designPatterns.structural.proxy;
/**
* @description: Dao层
* @author: xz
*/
public interface OrderDao {
int insert(Order order);
}
5、创建Dao实现层
package com.rf.designPatterns.structural.proxy;
/**
* @description: Dao实现层
* @author: xz
*/
public class OrderDaoImpl implements OrderDao{
@Override
public int insert(Order order) {
System.out.println("Dao层添加订单成功");
return 1;
}
}
6、创建Service实现层
package com.rf.designPatterns.structural.proxy;
/**
* @description: Service实现层
* @author: xz
*/
public class OrderServiceImpl implements OrderService{
private OrderDao orderDao;
@Override
public int saveOrder(Order order) {
//spring会自动注入，这里我们自己直接new
orderDao=new OrderDaoImpl();
System.out.println("Service调用Dao层的inser方法添加订单");
orderDao.insert(order);
return 1;
}
}
7、创建数据源上下文类
package com.rf.designPatterns.structural.proxy.db;
/**
* @description: 数据源上下文类
* @author: xz
*/
public class DataSourceContextHolder {
private static final ThreadLocal CONTEXT_HOLDER=new ThreadLocal();
public static void setDBType(String dbType){
CONTEXT_HOLDER.set(dbType);
}
public static String getDBType(){
return CONTEXT_HOLDER.get();
}
public static void clearDBType(){
CONTEXT_HOLDER.remove();
}
}
8、创建动态的数据源类
package com.rf.designPatterns.structural.proxy.db;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
/**
* @description: 动态的数据源类
* @author: xz
*/
public class DynamicDataSource extends AbstractRoutingDataSource {
@Override
protected Object determineCurrentLookupKey() {
return DataSourceContextHolder.getDBType();
}
}
9、创建Service层的静态代理
package com.rf.designPatterns.structural.proxy.staticProxy;
import com.rf.designPatterns.structural.proxy.Order;
import com.rf.designPatterns.structural.proxy.OrderService;
import com.rf.designPatterns.structural.proxy.OrderServiceImpl;
import com.rf.designPatterns.structural.proxy.db.DataSourceContextHolder;
/**
* @description: Service层的静态代理
* @author: xz
*/
public class OrderServiceStaticProxy {
//在静态代理类中声明OrderService来注入目标对象，即OrderService就是目标对象
private OrderService orderService;
//增强目标对象中的方法，使用同样的方法名，也可以使用不同的方法名
public int saveOrder(Order order){
beforeMethod(order);
orderService=new OrderServiceImpl();
int result=orderService.saveOrder(order);
afterMethod();
return result;
}
private void beforeMethod(Order order){
System.out.println("静态代理before代码， 在saveOrder方法之前执行");
int userId=order.getUserId();
int dbRouter=userId % 2;
System.out.println("静态代理分配到 db【" +dbRouter+ "】 数据库处理数据");
DataSourceContextHolder.setDBType("db"+String.valueOf(dbRouter));
}
private void afterMethod(){
System.out.println("静态代理after代码， 在saveOrder方法之后执行");
}
}
10、创建测试类
package com.rf.designPatterns.structural.proxy.staticProxy;
import com.rf.designPatterns.structural.proxy.Order;
/**
* @description: 静态代理测试类
* @author: xz
*/
public class Test {
public static void main(String[] args) {
Order order=new Order();
order.setUserId(1);
OrderServiceStaticProxy staticProxy =new OrderServiceStaticProxy();
staticProxy.saveOrder(order);
System.out.println("===================");
Order order2=new Order();
order2.setUserId(2);
OrderServiceStaticProxy staticProxy2 =new OrderServiceStaticProxy();
staticProxy2.saveOrder(order2);
}
}
11、测试结果如下图：
