解释器模式-Interpreter

1 package com.cgj.pattern.interpreter;
2 
3 /**
4  * 声明一个抽象的解释操作,这个接口为抽象语法树中所有节点所共享.
5  */
6 public interface AbstractExpression {
7 
8     public abstract void interpret(Context context);
9 }

 1 package com.cgj.pattern.interpreter;
 2 
 3 public class AExpression implements AbstractExpression {
 4 
 5     @Override
 6     public void interpret(Context context) {
 7         System.out.println("解释器A");
 8     }
 9 
10 }

 1 package com.cgj.pattern.interpreter;
 2 
 3 public class BExpression implements AbstractExpression {
 4 
 5     @Override
 6     public void interpret(Context context) {
 7         System.out.println("解释器B");
 8     }
 9 
10 }

 1 package com.cgj.pattern.interpreter;
 2 
 3 /**
 4  * 包含解释器之外的一些全局信息
 5  */
 6 public class Context {
 7 
 8     private String input;
 9     private String output;
10 
11     public String getInput() {
12         return input;
13     }
14 
15     public void setInput(String input) {
16         this.input = input;
17     }
18 
19     public String getOutput() {
20         return output;
21     }
22 
23     public void setOutput(String output) {
24         this.output = output;
25     }
26 
27 }

 1 package com.cgj.pattern.interpreter;
 2 
 3 import java.util.ArrayList;
 4 import java.util.List;
 5 
 6 public class Test {
 7 
 8     public static void main(String[] args) {
 9         Context context = new Context();
10 
11         // 何时使用用哪个解释器,应该由Context的内容决定,此处省略该过程
12         List<AbstractExpression> expressions = new ArrayList<AbstractExpression>();
13         expressions.add(new AExpression());
14         expressions.add(new BExpression());
15         expressions.add(new AExpression());
16         expressions.add(new BExpression());
17         expressions.add(new BExpression());
18         expressions.add(new AExpression());
19 
20         for (AbstractExpression expression : expressions) {
21             expression.interpret(context);
22         }
23     }
24 
25 }