代理模式属于结构型模式，分为静态代理和动态代理。
静态代理
直接演示案例，数据库分库分表的时候，多个数据源之间的切换，需要用到数据源路由；
实体Order：
@Data
public class Order {
private Object orderInfo;
private Long createTime;
private String id;
}
dao层：
public class OrderDao {
public int insert(Order order) {
System.out.println("创建新order");
return 1;
}
}
service层：
// 接口
public interface IOrderService {
int createOrder(Order order);
}
// 实现类
public class OrderService implements IOrderService{
private OrderDao orderDao;
public OrderService(){
orderDao = new OrderDao();
}
@Override
public int createOrder(Order order) {
System.out.println("orderService创建订单");
return orderDao.insert(order);
}
}
动态数据源：
public class DynamicDataSourceEntry {
public final static String DEFAULT_SOURCE = null;
private final static ThreadLocal<String> LOCAL = new ThreadLocal<>();
public DynamicDataSourceEntry() {
}
/**
* 清空数据源
*/
public static void clear(){
LOCAL.remove();
}
/**
* 获取当前数据源名称
* @return
*/
public static String get(){
return LOCAL.get();
}
/**
* 还原当前切换的数据源
*/
public static void restore(){
LOCAL.set(DEFAULT_SOURCE);
}
/**
* 设置已知名字的数据源
* @param source
*/
public static void set(String source){
LOCAL.set(source);
}
/**
* 根据年份动态设置数据源
* @param year
*/
public static void set(int year){
LOCAL.set("DB_"+year);
}
}
静态代理类：
public class OrderServiceStaticProxy implements IOrderService {
private IOrderService orderService;
public OrderServiceStaticProxy(IOrderService orderService){
this.orderService = orderService;
}
@Override
public int createOrder(Order order){
before();
int result = 0;
try {
Long createTime = order.getCreateTime();
SimpleDateFormat yearFormat = new SimpleDateFormat("yyyy");
Integer dbRouter = Integer.valueOf(yearFormat.format(new Date(createTime)));
System.out.println("静态代理怼到【DB_"+dbRouter+"】数据源");
DynamicDataSourceEntry.set(dbRouter);
result = orderService.createOrder(order);
return result;
} catch (NumberFormatException e) {
e.printStackTrace();
} finally {
after();
}
return result;
}
private void before(){
System.out.println("代理前执行");
}
private void after(){
System.out.println("代理后执行");
}
}
测试：
@Test
public void test() throws ParseException {
try {
Order order = new Order();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");
Date date = sdf.parse("2019/02/01");
order.setCreateTime(date.getTime());
order.setId("1");
order.setOrderInfo(new ArrayList<String>());
// 创建订单
OrderServiceStaticProxy orderService = new OrderServiceStaticProxy(new OrderService());
int order1 = orderService.createOrder(order);
System.out.println("order1 = " + order1);
} catch (ParseException e) {
e.printStackTrace();
}
}
运行结果：
代理前执行
静态代理怼到【DB_2019】数据源
orderService创建订单
创建新order
代理后执行
order1 = 1
