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notes/设计模式.md

@@ -473,7 +473,118 @@ public class Client {
 
 ### 意图
 
-将命令封装进对象中；允许使用命令对象对客户对象进行参数化；允许将命令对象存放到队列中。
+将命令封装成对象中，以便使用命令来参数化其它对象，或者将命令对象放入队列中进行排队，或者将命令对象的操作记录到日志中，以及支持可撤销的操作。
+
+### 类图
+
+- Command：命令
+- Receiver：命令接收者，也就是命令真正的执行者
+- Invoker：通过它来调用命令
+- Client：可以设置命令与命令的接收者
+
+<div align="center"> <img src="../pics//ae1b27b8-bc13-42e7-ac12-a2242e125499.png"/> </div><br>
+
+### 实现
+
+设计一个要控制，可以控制电灯开关。
+
+<div align="center"> <img src="../pics//e6bded8e-41a0-489a-88a6-638e88ab7666.jpg"/> </div><br>
+
+```java
+public interface Command {
+    void execute();
+}
+```
+
+```java
+public class LightOnCommand implements Command {
+    Light light;
+
+    public LightOnCommand(Light light) {
+        this.light = light;
+    }
+
+    @Override
+    public void execute() {
+        light.on();
+    }
+}
+```
+
+```java
+public class LightOffCommand implements Command {
+    Light light;
+
+    public LightOffCommand(Light light) {
+        this.light = light;
+    }
+
+    @Override
+    public void execute() {
+        light.off();
+    }
+}
+```
+
+```java
+public class Light {
+
+    public void on() {
+        System.out.println("Light is on!");
+    }
+
+    public void off() {
+        System.out.println("Light is off!");
+    }
+}
+```
+
+```java
+/**
+ * 遥控器
+ */
+public class Invoker {
+    private Command[] onCommands;
+    private Command[] offCommands;
+    private final int slotNum = 7;
+
+    public Invoker() {
+        this.onCommands = new Command[slotNum];
+        this.offCommands = new Command[slotNum];
+    }
+
+    public void setOnCommand(Command command, int slot) {
+        onCommands[slot] = command;
+    }
+
+    public void setOffCommand(Command command, int slot) {
+        offCommands[slot] = command;
+    }
+
+    public void onButtonWasPushed(int slot) {
+        onCommands[slot].execute();
+    }
+
+    public void offButtonWasPushed(int slot) {
+        offCommands[slot].execute();
+    }
+}
+```
+
+```java
+public class Client {
+    public static void main(String[] args) {
+        Invoker invoker = new Invoker();
+        Light light = new Light();
+        Command lightOnCommand = new LightOnCommand(light);
+        Command lightOffCommand = new LightOffCommand(light);
+        invoker.setOnCommand(lightOnCommand, 0);
+        invoker.setOffCommand(lightOffCommand, 0);
+        invoker.onButtonWasPushed(0);
+        invoker.offButtonWasPushed(0);
+    }
+}
+```
 
 ### JDK
 
@@ -1336,6 +1447,8 @@ public class Client {
 
 ### 实现
 
+观看电影需要操作很多电器，使用外观模式可以实现一键看电影功能。
+
 ```java
 public class SubSystem {
     public void turnOnTV() {