解释器模式

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。




基本就这样，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！