观察者模式

Folgerjun · web-flow · commit 4fa3d0f087d1 · 2018-03-12T10:45:41.000+08:00
观察者模式
diff --git a/java-des/src/com/java/design/observer/Observer.java b/java-des/src/com/java/design/observer/Observer.java
@@ -0,0 +1,12 @@
+package com.java.design.observer;
+
+/**
+ * 观察者接口
+ * 
+ * @author Administrator
+ *
+ */
+public interface Observer {
+
+	void update(String message);
+}
diff --git a/java-des/src/com/java/design/observer/ObserverPattern.java b/java-des/src/com/java/design/observer/ObserverPattern.java
@@ -0,0 +1,32 @@
+package com.java.design.observer;
+
+/**
+ * 观察者模式 -----> 在对象之间定义了一对多的依赖，这样一来，当一个对象改变状态，依赖它的对象会收到通知并自动更新。
+ * 
+ * 其实就是发布订阅模式，发布者发布信息，订阅者获取信息，订阅了就能收到信息，没订阅就收不到信息
+ * 
+ * @author Administrator
+ *
+ */
+public class ObserverPattern {
+
+	public static void main(String[] args) {
+
+		ObserverServer observerServer = new ObserverServer();
+		Observer observerA = new User("A");
+		Observer observerB = new User("B");
+		Observer observerC = new User("C");
+
+		observerServer.add(observerA);
+		observerServer.add(observerB);
+		observerServer.add(observerC);
+		observerServer.setInfomation("PHP是世界上最好的语言 ...");
+
+		System.out.println("------------------------------");
+
+		observerServer.remove(observerB);
+		observerServer.setInfomation("JAVA是世界上最好的语言 ...");
+
+	}
+
+}
diff --git a/java-des/src/com/java/design/observer/ObserverServer.java b/java-des/src/com/java/design/observer/ObserverServer.java
@@ -0,0 +1,50 @@
+package com.java.design.observer;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * 被观察者服务
+ * 
+ * @author Administrator
+ *
+ */
+public class ObserverServer implements Observerable {
+
+	private List<Observer> observers;
+	private String message;
+
+	public ObserverServer() {
+		observers = new ArrayList<Observer>();
+	}
+
+	@Override
+	public void add(Observer observer) {
+
+		observers.add(observer);
+	}
+
+	@Override
+	public void remove(Observer observer) {
+
+		if (!observers.isEmpty()) {
+			observers.remove(observer);
+		}
+	}
+
+	@Override
+	public void notifyObs() {
+
+		for (int i = 0; i < observers.size(); i++) {
+			Observer obs = observers.get(i);
+			obs.update(message);
+		}
+	}
+
+	public void setInfomation(String message) {
+		this.message = message;
+		System.out.println("服务更新消息：" + message);
+		notifyObs();
+	}
+
+}
diff --git a/java-des/src/com/java/design/observer/Observerable.java b/java-des/src/com/java/design/observer/Observerable.java
@@ -0,0 +1,31 @@
+package com.java.design.observer;
+
+/**
+ * 被观察者接口 / 声明了添加、删除、通知观察者方法
+ * 
+ * @author Administrator
+ *
+ */
+public interface Observerable {
+
+	/**
+	 * 添加观察者
+	 * 
+	 * @param observer
+	 */
+	void add(Observer observer);
+
+	/**
+	 * 删除观察者
+	 * 
+	 * @param observer
+	 */
+	void remove(Observer observer);
+
+	/**
+	 * 通知观察者
+	 *
+	 */
+	void notifyObs();
+
+}
diff --git a/java-des/src/com/java/design/observer/User.java b/java-des/src/com/java/design/observer/User.java
@@ -0,0 +1,23 @@
+package com.java.design.observer;
+
+public class User implements Observer {
+
+	private String name;
+	private String message;
+
+	public User(String name) {
+		this.name = name;
+	}
+
+	@Override
+	public void update(String message) {
+
+		this.message = message;
+		read();
+	}
+
+	public void read() {
+
+		System.out.println(name + "收到推送消息：" + message);
+	}
+}
