memento

Author: code4craft

src/main/java/helloworld/Main.java

@@ -10,6 +10,7 @@
 import helloworld.behavioral.mediator.HelloWorldMediator;
 import helloworld.behavioral.mediator.HelloWorldSlogan;
 import helloworld.behavioral.mediator.HelloWorldTarget;
+import helloworld.behavioral.memento.HelloWorldMementoOriginator;
 import helloworld.creational.abstract_factory.AbstractFactory;
 import helloworld.creational.abstract_factory.SplitHelloWorldFactory;
 import helloworld.creational.builder.HelloWorldBuilder;
@@ -107,5 +108,11 @@ public static void main(String[] args) throws InstantiationException, IllegalAcc
         helloWorldTarget.setHelloWorldMediator(helloWorldMediator);
         System.out.println(helloWorldTarget.helloWorld());
 
+        HelloWorldMementoOriginator helloWorldMementoOriginator = new HelloWorldMementoOriginator();
+        HelloWorldMementoOriginator.Memento memento = helloWorldMementoOriginator.set("Hello Memento!").saveToMemento();
+        helloWorldMementoOriginator.set("Hello Whatever!");
+        helloWorldMementoOriginator.restoreFromMemento(memento);
+        System.out.println(helloWorldMementoOriginator.helloWorld());
+
     }
 }

src/main/java/helloworld/behavioral/memento/HelloWorldMementoOriginator.java

@@ -0,0 +1,41 @@
+package helloworld.behavioral.memento;
+
+import helloworld.HelloWorld;
+
+/**
+ * @author yihua.huang@dianping.com
+ */
+public class HelloWorldMementoOriginator implements HelloWorld{
+
+    private String state;
+
+    public HelloWorldMementoOriginator set(String state) {
+        this.state = state;
+        return this;
+    }
+
+    public Memento saveToMemento() {
+        return new Memento(state);
+    }
+
+    public void restoreFromMemento(Memento memento) {
+        state = memento.getSavedState();
+    }
+
+    @Override
+    public String helloWorld() {
+        return state;
+    }
+
+    public static class Memento {
+        private final String state;
+
+        public Memento(String stateToSave) {
+            state = stateToSave;
+        }
+
+        public String getSavedState() {
+            return state;
+        }
+    }
+}

src/test/java/helloworld/behavioral/memento/HelloWorldMementoTest.java

@@ -0,0 +1,25 @@
+package helloworld.behavioral.memento;
+
+import helloworld.behavioral.mediator.HelloWorldMediator;
+import helloworld.behavioral.mediator.HelloWorldSlogan;
+import helloworld.behavioral.mediator.HelloWorldTarget;
+import org.junit.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+
+/**
+ * @author yihua.huang@dianping.com
+ */
+public class HelloWorldMementoTest {
+
+    @Test
+    public void testHelloWorldMediator(){
+        HelloWorldMementoOriginator helloWorldMementoOriginator = new HelloWorldMementoOriginator();
+        HelloWorldMementoOriginator.Memento memento = helloWorldMementoOriginator.set("Hello Memento!").saveToMemento();
+        helloWorldMementoOriginator.set("Hello Whatever!");
+        assertThat(helloWorldMementoOriginator.helloWorld(),is("Hello Whatever!"));
+        helloWorldMementoOriginator.restoreFromMemento(memento);
+        assertThat(helloWorldMementoOriginator.helloWorld(),is("Hello Memento!"));
+    }
+}