状态模式

当对象的状态改变时，同时改变其行为

这让我想到了iOS 中按钮不同状态，绑定不同的方法和不同的title等～～

//State类是个状态类
public class State {  
      
    private String value;  
      
    public void method1(){  
        System.out.println("execute the first opt!");  
    }  
    public void method2(){  
        System.out.println("execute the second opt!");  
    }  
}

//Context类实现切换
public class Context {  
  
    private State state;  
  
    public Context(State state) {  
        this.state = state;  
    }  
    public State getState() {  
        return state;  
    }  
    public void setState(State state) {  
        this.state = state;  
    }  
    public void method() {  
        if (state.getValue().equals("state1")) {  
            state.method1();  
        } else if (state.getValue().equals("state2")) {  
            state.method2();  
        }  
    }  
} 

//测试
public class Test {  
  
    public static void main(String[] args) {  
          
        State state = new State();  
        Context context = new Context(state);  
          
        //设置第一种状态  
        state.setValue("state1");  
        context.method();  
        //设置第二种状态  
        state.setValue("state2");  
        context.method();  
    }  
}

状态模式在日常开发中确实用的挺多的.......

父文链接