解释器模式是我们暂时的最后一讲,一般主要应用在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;
} }
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);
}
}
最后输出正确的结果:3。