//备忘录模式定义: //在不破坏封装性的前提下,捕获一个对象的内部状态,并在该对象之外保存这个状态。 //这样以后就可以将该对象恢复到原先保存的状态 //实例:测试两种方案,两种方案在第一阶段的过程是相同的,第二阶段是不同的 //实例代码 //备忘录对象的窄接口 public interface FlowAMockMemento { //空的,所谓窄接口,即只是一个标识作用,它的持有者不可以调用任何它的方法 } //测试流程类 public class FlowAMock { private String flowName; private int tempResult; private String tempState; public FlowAMock(String flowName) { this.flowName = flowName; } public void runPhaseOne() { tempResult = 3; tempState = "PhaseOne"; } public void shema1() { this.tempState += ",Schema1"; System.out.pritnln(this.tempState+":now run"+tempResult); this.tempResult += 11; } public void schema2() { this.tempState += ",Schema2"; System.out.pritnln(this.tempState+":now run"+tempResult); this.tempResult += 22; } public FlowAMockMemento createMemento() { return new MementoImpl(this.tempResult, this.tempState); } public void setMemento(FlowAMockMemento memento) { MementoImpl mementoImpl = (MementoImpl)memento; this.tempResult = mementoImpl.getTempResult(); this.tempState = mementoImpl.getTempState(); } private static class MemetoImpl implements FlowAMockMemento { private int tempResult; private String tempState; public MemetoImpl(int tempResult, String tempState) { this.tempResult = tempResult; this.tempState = tempState; } public int getTempResult() { return tempResult; } public int getTempState() { return tempState; } } } //备忘录管理类 public class FlowAMementoCareTaker { private FlowAMockMemento memento = null; public void saveMemento(FlowAMockMemento memento) { this.memento = memento; } public FlowAMockMemento retriveMemento() { return this.memento; } } //客户端 public class Client { public static void main(String[] args) { FlowAMock mock = new FlowAMock("TestFlow"); mock.runPhaseOne(); FlowAMementoCareTaker careTaker = new FlowAMementoCareTaker(); FlowAMockMemento memento = mock.createMemento(); careTaker.saveMemento(memento); mock.schema1();//运行第一种方案 mock.setMemento(careTaker.retriveMemento());//恢复数据 mock.schema2();//运行第二种发难 } } //备忘录模式本质:保存和恢复内部状态 //优点:更好的封装性,由于使用了内部类和窄接口,所以外部就算持有备忘录接口对象也无法访问其中的属性 //备忘录模式中内部内和窄接口是最给力的设计,这样给把对象的接口给外部保存 //但是接口中没有方法,所以外部无法访问,充分保证了封装性 //只有创建它的原发器才可以设置和获取它的值
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原文:http://blog.csdn.net/dfwseq/article/details/25660095