initialize

Author: tim-chow

State/README.md

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+### 简介  
+状态模式允许对象在其内部状态发生变化时，改变其行为。  
+比如，空调在*关机*状态时的行为，只能是*开机*；而在*开机*状态时的行为，可以是制冷，制热，关闭等。   
+
+---
+
+### 角色  
+
+* Context
+环境角色，也称为上下文角色。它定义了客户端*感兴趣*的接口，同时会在内部保存一个具体状态对象的引用。这个具体状态对象代表环境对象当前所处的状态   
+* State
+抽象状态角色。它为所有的具体状态类定义了公共的接口  
+* ConcreteState  
+继承或实现抽象状态角色。一个具体状态类定义了**一组特定的行为**  
+
+---
+
+### UML类图   
+
+![state.png](http://timd.cn/content/images/pictures/state.png)  
+

State/StatePattern.java

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+class Context {
+    private final AirConditioningState open =
+        new OpenState();
+    private final AirConditioningState close =
+        new CloseState();
+    private final AirConditioningState cool = 
+        new CoolState();
+    private final AirConditioningState heat = 
+        new HeatState();
+    private AirConditioningState currentState = close;
+
+    public void toOpen() {
+        if (currentState.open())
+            currentState = open;
+    }
+
+    public void toClose() {
+        if (currentState.close())
+            currentState = close;
+    }
+
+    public void toCool() {
+        if (currentState.cool())
+            currentState = cool;
+    }
+
+    public void toHeat() {
+        if (currentState.heat())
+            currentState = heat;
+    }
+}
+
+abstract class AirConditioningState {
+    public boolean open() {
+        System.out.println("illegal state, unable to open");
+        return false;
+    }
+
+    public boolean close() {
+        System.out.println("illegal state, unable to close");
+        return false;
+    }
+
+    public boolean cool() {
+        System.out.println("illegal state, unable to cool");
+        return false;
+    }
+
+    public boolean heat() {
+        System.out.println("illegal state, unable to heat");
+        return false;
+    }
+}
+
+class OpenState extends AirConditioningState {
+    public boolean close() {
+        System.out.println("change to state: `close`");
+        return true;
+    }
+
+    public boolean cool() {
+        System.out.println("change to state: `cool`");
+        return true;
+    }
+
+    public boolean heat() {
+        System.out.println("change to state: `heat`");
+        return true;
+    }
+}
+
+class CloseState extends AirConditioningState {
+    public boolean open() {
+        System.out.println("change to state: `open`");
+        return true;
+    }
+}
+
+class CoolState extends AirConditioningState {
+    public boolean close() {
+        System.out.println("change to state: `close`");
+        return true;
+    }
+
+    public boolean heat() {
+        System.out.println("change to state: `heat`");
+        return true;
+    }
+}
+
+class HeatState extends AirConditioningState {
+    public boolean close() {
+        System.out.println("change to state: `close`");
+        return true;
+    }
+
+    public boolean cool() {
+        System.out.println("change to state: `cool`");
+        return true;
+    }
+}
+
+
+public class StatePattern {
+    public static void main(String[] args) {
+        Context context = new Context();
+        context.toHeat();
+        context.toOpen();
+        context.toHeat();
+        context.toCool();
+        context.toClose();
+        context.toClose();
+    }
+}
+

State/StatePattern.py

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+class Context:
+    def __init__(self):
+        self._open = OpenState()
+        self._close = CloseState()
+        self._cool = CoolState()
+        self._heat = HeatState()
+        self._current_state = self._close;
+
+    def to_open(self):
+        if self._current_state.open():
+            self._current_state = self._open
+
+    def to_close(self):
+        if self._current_state.close():
+            self._current_state = self._close
+
+    def to_cool(self):
+        if self._current_state.cool():
+            self._current_state = self._cool
+
+    def to_heat(self):
+        if self._current_state.heat():
+            self._current_state = self._heat
+
+class AirContiditoningState:
+    def open(self):
+        print("illegal state, unable to open")
+        return False
+
+    def close(self):
+        print("illegal state, unable to close")
+        return False
+
+    def cool(self):
+        print("illegal state, unable to cool")
+        return False
+
+    def heat(self):
+        print("illegal state, unable to heat")
+        return False
+
+class OpenState(AirContiditoningState):
+    def close(self):
+        print("change to state: `close`")
+        return True
+
+    def cool(self):
+        print("change to state: `cool`")
+        return True
+
+    def heat(self):
+        print("change to state: `heat`")
+        return True
+
+class CloseState(AirContiditoningState):
+    def open(self):
+        print("change to state: `open`")
+        return True
+
+class CoolState(AirContiditoningState):
+    def close(self):
+        print("change to state: `close`")
+        return True
+
+    def heat(self):
+        print("change to state: `heat`")
+        return True
+
+class HeatState(AirContiditoningState):
+    def close(self):
+        print("change to state: `close`")
+        return True
+
+    def cool(self):
+        print("change to state: `cool`")
+        return True
+
+if __name__ == "__main__":
+    context = Context()
+    context.to_heat();
+    context.to_open();
+    context.to_heat();
+    context.to_cool();
+    context.to_close();
+    context.to_close();
+