委托者: 实际服务提供者
代理者: 中间商
客户: 服务的消费者
根据代理类在运行前是否存在,分为:
静态代理: 运行前已存在代理类
动态代理: 运行前未存在代理类
厂家(Vendor)生产产品, 厂家可以直接销售给用户(Customer), 也可以通过代理商(Agent)销售给用户.代理商不直接囤货,有客户需求再让
厂家发货销售. 类似于微商.
Vendor -> Customer
有的地方只有一级代理, 直接面向用户:
Vendor -> Agent -> Customer
有的地方有一级代理商和二级代理商, 其中二级代理商直接面向用户, 一级代理商做厂家和二级代理商的中间媒介,根据实际需求做一些事情.
比如给二级代理商售前培训, 售后的结算等等.
Vendor -> Proxy -> Agent -> Customer
销售接口:
public interface Sell { /** * 售卖 */ void sell(); }
生产者:
public class Vendor implements Sell { @Override public void sell() { System.out.println("Vendor sell."); } }
直接销售代理:
public class BusinessAgent implements Sell { private Vendor vendor; public BusinessAgent(Vendor vendor) { this.vendor =vendor; } @Override public void sell() { System.out.println("BusinessAgent sell."); // 代理商只卖给学生, 即为在不修改委托的情况下增加额外操作. if (isStudent()) { vendor.sell(); } } private boolean isStudent() { boolean isStudent = new Random().nextBoolean(); System.out.println("isStudent:" + isStudent); return isStudent; } }
动态代理拦截:
public class DynamicProxy implements InvocationHandler { //接口的实现类 private Object object; public DynamicProxy(Object o) { this.object = o; } @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { System.out.println("=========给代理商培训=========="); //实现类对象object调用方法method并传入参数args Object o = method.invoke(object, args); System.out.println("=========售后维护结算=========="); return o; } }
生成动态代理文件:
System.out.println("==========exe:dynamicProxy=========="); //生成一个二级代理商 BusinessAgent agent = new BusinessAgent(new Vendor()); //根据实际需要生成一个一级代理 DynamicProxy dynamicProxy = new DynamicProxy(agent); //生成动态代理文件 System.getProperties().put("sun.misc.ProxyGenerator.saveGeneratedFiles","true"); //获取Sell接口的实例 Sell sell = (Sell) Proxy.newProxyInstance(Sell.class.getClassLoader(), new Class[]{Sell.class}, dynamicProxy); //售卖产品 sell.sell();
动态代理类文件:
public final class $Proxy0 extends Proxy implements Sell { private static Method m1; private static Method m2; //Sell的的sell方法 private static Method m3; private static Method m0; static { try { m1 = Class.forName("java.lang.Object").getMethod("equals", Class.forName("java.lang.Object")); m2 = Class.forName("java.lang.Object").getMethod("toString"); //获取Sell 的 sell方法 m3 = Class.forName("net.devwiki.pattern.proxy.Sell").getMethod("sell"); m0 = Class.forName("java.lang.Object").getMethod("hashCode"); } catch (NoSuchMethodException var2) { throw new NoSuchMethodError(var2.getMessage()); } catch (ClassNotFoundException var3) { throw new NoClassDefFoundError(var3.getMessage()); } } public $Proxy0(InvocationHandler var1) throws { super(var1); } public final boolean equals(Object var1) throws { try { return (Boolean)super.h.invoke(this, m1, new Object[]{var1}); } catch (RuntimeException | Error var3) { throw var3; } catch (Throwable var4) { throw new UndeclaredThrowableException(var4); } } public final String toString() throws { try { return (String)super.h.invoke(this, m2, (Object[])null); } catch (RuntimeException | Error var2) { throw var2; } catch (Throwable var3) { throw new UndeclaredThrowableException(var3); } } //覆写Sell类的sell方法 public final void sell() throws { try { // h为InvocationHandler的实例, 调用DynamicProxy的invoke方法 //进而调用实现类的sell方法 //如果外部传入的是Vendor则直接是调用Vendor的sell //如果外部传入的是BusinessAgent, 则中间添加学生过滤 super.h.invoke(this, m3, (Object[])null); } catch (RuntimeException | Error var2) { throw var2; } catch (Throwable var3) { throw new UndeclaredThrowableException(var3); } } public final int hashCode() throws { try { return (Integer)super.h.invoke(this, m0, (Object[])null); } catch (RuntimeException | Error var2) { throw var2; } catch (Throwable var3) { throw new UndeclaredThrowableException(var3); } } }