學習了What is IAdaptable?這篇文章,有點困惑,干脆做個demo鞏固下,包括三個部分:OldObject 、NewObject和工廠類YearFactory

 

import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.Platform;

// 實現了IAdaptable 接口
public class OldObject implements IAdaptable {
	private String yearmonthday;

	public String getYearmonthday() {
		return yearmonthday;
	}

	public void setYearmonthday(String yearmonthday) {
		this.yearmonthday = yearmonthday;
	}

	public Object getAdapter(Class adapter) {
		return Platform.getAdapterManager().getAdapter(this, adapter);
	}

}
public class NewObject {
    private String year; 

    public String getYear() {
        return year;
    } 

    public void setYear(String year) {
        this.year = year;
    } 

}
 
完成具體的轉換
import org.eclipse.core.runtime.IAdapterFactory;
public class YearFactory implements IAdapterFactory {
	private static final Class[] types = { NewObject.class };

	public Object getAdapter(Object old, Class clazz) {
		if (clazz == NewObject.class && old instanceof OldObject) {
			NewObject objectNew= new NewObject();
			objectNew.setYear(((OldObject) old).getYearmonthday().substring(2)); //隨意的規則
			return objectNew;
		} else {
			return null;
		}

	}

	public Class[] getAdapterList() {
		return types;
	}

}
 
調用轉換的代碼:
Platform.getAdapterManager().registerAdapters(new YearFactory(), OldObject.class);
OldObject old = new OldObject();
old.setYearmonthday("20070914");
Object adaptable = old.getAdapter(NewObject.class);
if (adaptable != null) { 
    NewObject node = (NewObject) adaptable; 
   System.out.println(node.getYear());
 } 

總結:

術語:源對象、轉換類型、工廠

目的:實現兩個不相關對象的轉換

 

(1)源對象需要實現IAdaptable接口,或者繼承PlatformObject抽象類

(2)在源對象IAdaptable接口方法getAdapter的實現可以如下,即直接轉發給AdapterManager的getAdapter()方法

 public Object getAdapter(Class adapter) {
    return Platform.getAdapterManager().getAdapter(this, adapter);
}
(3)實現轉換工廠類,具體負責轉換,需要實現IAdapterFactory接口,其接口方法getAdapterList()負責通知AdapterManager轉換類型,
而getAdapter方法具體完成轉換
(4)將轉換工廠類注冊到AdapterManager:
Platform.getAdapterManager().registerAdapters(new YearFactory(), OldObject.class); 
 
這樣的好處在于,如果源對象需要轉換到多個不相關的對象的時候,不需要修改源對象,而直接轉發給相應的工廠類,這樣在一定程度上保護了源對象免于修改,
而是修改或者增加新的工廠類。