装饰模式（Decorator）简单示例

王树东 — Thu, 23 Feb 2012 14:50:00 GMT

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经常在别人的代码里看见 XWrapper，YWrapper，ZWrapper，原来这种编程的策略就是装饰模式。装饰模式的类图如下：

1
2//Component
3interface IDataRetriever{
4    String getData();
5}
6//Concrete Component
7class DataRetriever implements IDataRetriever{
8    String getData(){
9        return "Retrieve Data.";
10    }
11}
12//Abstract Decorator
13abstract class AbstractDataRetriever implements IDataRetriever{
14    protected IDataRetriever retriever;
15    public AbstractDataRetriever(IDataRetriever retriever){
16        this.retriever = retriever;
17    }
18}
19//Concrete Decorator
20class DataRetrieverWrapper extends AbstractDataRetriever{
21    DataRetrieverWrapper(IDataRetriever retriever){
22        super(retriever);
23    }
24    String getData(){
25        println "processing data";
26        this.retriever.getData();
27    }
28}
29
30def retriever = new DataRetriever();
31def wrapper = new DataRetrieverWrapper(retriever);
32wrapper.getData();
33
34
35class DatabaseRetriever implements IDataRetriever{
36    String getData(){
37        return "Retrieve Data from Database";
38   }
39}
40
41
42wrapper = new DataRetrieverWrapper(new DatabaseRetriever());
43wrapper.getData();
44
45

王树东 2012-02-23 22:50 发表评论

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装饰模式（Decorator）简单示例