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。