Update 设计模式 - 中介者.md

重新绘制类图 dp-mediator.png；对代码实现进行文字校对，补充中介者模式优缺点分析，并调整 JDK 应用小节的内容描述。

notes/设计模式 - 中介者.md

@@ -4,8 +4,8 @@
 集中相关对象之间复杂的沟通和控制方式。
 
 ### 类图
-- Mediator：中介者，定义一个接口用于与各同事（Colleague）对象通信。
-- Colleague：同事，相关对象
+- Mediator：中介者，定义一个接口用于与各同事（Colleague）对象通信；
+- Colleague：同事，需要互相协作的相关对象。
 
 <div align="center"> <img src="pics/dp-mediator.png" width="760px"/> </div><br>
 
@@ -52,14 +52,14 @@ public class CoffeePot extends Colleague {
 ```
 
 ```java
-public class Calender extends Colleague {
+public class Calendar extends Colleague {
     @Override
     public void onEvent(Mediator mediator) {
-        mediator.doEvent("calender");
+        mediator.doEvent("calendar");
     }
 
-    public void doCalender() {
-        System.out.println("doCalender()");
+    public void doCalendar() {
+        System.out.println("doCalendar()");
     }
 }
 ```
@@ -87,13 +87,13 @@ public abstract class Mediator {
 public class ConcreteMediator extends Mediator {
     private Alarm alarm;
     private CoffeePot coffeePot;
-    private Calender calender;
+    private Calendar calendar;
     private Sprinkler sprinkler;
 
-    public ConcreteMediator(Alarm alarm, CoffeePot coffeePot, Calender calender, Sprinkler sprinkler) {
+    public ConcreteMediator(Alarm alarm, CoffeePot coffeePot, Calendar calendar, Sprinkler sprinkler) {
         this.alarm = alarm;
         this.coffeePot = coffeePot;
-        this.calender = calender;
+        this.calendar = calendar;
         this.sprinkler = sprinkler;
     }
 
@@ -106,8 +106,8 @@ public class ConcreteMediator extends Mediator {
             case "coffeePot":
                 doCoffeePotEvent();
                 break;
-            case "calender":
-                doCalenderEvent();
+            case "calendar":
+                doCalendarEvent();
                 break;
             default:
                 doSprinklerEvent();
@@ -117,7 +117,7 @@ public class ConcreteMediator extends Mediator {
     public void doAlarmEvent() {
         alarm.doAlarm();
         coffeePot.doCoffeePot();
-        calender.doCalender();
+        calendar.doCalendar();
         sprinkler.doSprinkler();
     }
 
@@ -125,7 +125,7 @@ public class ConcreteMediator extends Mediator {
         // ...
     }
 
-    public void doCalenderEvent() {
+    public void doCalendarEvent() {
         // ...
     }
 
@@ -140,9 +140,9 @@ public class Client {
     public static void main(String[] args) {
         Alarm alarm = new Alarm();
         CoffeePot coffeePot = new CoffeePot();
-        Calender calender = new Calender();
+        Calendar calendar = new Calendar();
         Sprinkler sprinkler = new Sprinkler();
-        Mediator mediator = new ConcreteMediator(alarm, coffeePot, calender, sprinkler);
+        Mediator mediator = new ConcreteMediator(alarm, coffeePot, calendar, sprinkler);
         // 闹钟事件到达，调用中介者就可以操作相关对象
         alarm.onEvent(mediator);
     }
@@ -152,18 +152,19 @@ public class Client {
 ```text
 doAlarm()
 doCoffeePot()
-doCalender()
+doCalendar()
 doSprinkler()
 ```
 
+闹钟不知道还有咖啡壶和喷头，新增一个设备只需要修改 ConcreteMediator。需要注意的是，对象之间的交互逻辑都集中到了中介者中，设备多了以后中介者本身会变得庞大、难以维护。
+
 ### JDK 中的应用
-- All scheduleXXX() methods of [java.util.Timer](http://docs.oracle.com/javase/8/docs/api/java/util/Timer.html)
-- [java.util.concurrent.Executor#execute()](http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/Executor.html#execute-java.lang.Runnable-)
-- submit() and invokeXXX() methods of [java.util.concurrent.ExecutorService](http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ExecutorService.html)
-- scheduleXXX() methods of [java.util.concurrent.ScheduledExecutorService](http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ScheduledExecutorService.html)
-- [java.lang.reflect.Method#invoke()](http://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Method.html#invoke-java.lang.Object-java.lang.Object...-)
+- [java.util.Timer](http://docs.oracle.com/javase/8/docs/api/java/util/Timer.html) 的 scheduleXXX() 方法；
+- [java.util.concurrent.Executor#execute()](http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/Executor.html#execute-java.lang.Runnable-)；
+- [java.util.concurrent.ExecutorService](http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ExecutorService.html) 的 submit() 和 invokeXXX() 方法；
+- [java.util.concurrent.ScheduledExecutorService](http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ScheduledExecutorService.html) 的 scheduleXXX() 方法。
 
 ## 参考资料
 
 - 弗里曼. Head First 设计模式 [M]. 中国电力出版社, 2007.
-- Gamma E. 设计模式: 可复用面向对象软件的基础 [M]. 机械工业出版社, 2007.
+- Gamma E. 设计模式：可复用面向对象软件的基础 [M]. 机械工业出版社, 2007.