终：解释器模式

主要应用在OOP开发中的编译器的开发中，所以适用面比较窄

Context类是一个上下文环境类，Plus和Minus分别是用来计算的实现，代码如下：

public interface Expression {  
    public int interpret(Context context);  
}
public class Plus implements Expression {  
  
    @Override  
    public int interpret(Context context) {  
        return context.getNum1()+context.getNum2();  
    }  
}
public class Minus implements Expression {  
  
    @Override  
    public int interpret(Context context) {  
        return context.getNum1()-context.getNum2();  
    }  
}

public class Context {  
      
    private int num1;  
    private int num2;  
      
    public Context(int num1, int num2) {  
        this.num1 = num1;  
        this.num2 = num2;  
    }  
      
    public int getNum1() {  
        return num1;  
    }  
    public void setNum1(int num1) {  
        this.num1 = num1;  
    }  
    public int getNum2() {  
        return num2;  
    }  
    public void setNum2(int num2) {  
        this.num2 = num2;  
    }  
} 

//测试
public class Test {  
  
    public static void main(String[] args) {  
        // 计算9+2-8的值  
        int result = new Minus().interpret((new Context(new Plus()  
                .interpret(new Context(9, 2)), 8)));  
        System.out.println(result);  
    }  
}

解释器模式用来做各种各样的解释器，如正则表达式等的解释器等等！

父文链接