我如何將一般緩存的對象轉換爲具體的android

Question

我有一個對象緩存類，可以將對象保存在內存中，當我嘗試稍後檢索它時會出現問題。如何輸出通用對象，然後將其放入另一端的已定義對象中。這裏是類

public class ObjectCache implements Serializable{ 

private static final long serialVersionUID = 1L; 
private Context context; 
private String objectName; 
private Integer keepAlive = 86400; 

public ObjectCache(Context context,String objectName) { 
    this.context = context; 
    this.objectName = objectName; 
} 

public void setKeepAlive(Integer time) { 
    this.keepAlive = time; 
} 

public boolean saveObject(Object obj) { 

    final File cacheDir = context.getCacheDir(); 
    FileOutputStream fos = null; 
    ObjectOutputStream oos = null; 

    if (!cacheDir.exists()) { 
     cacheDir.mkdirs(); 
    } 

    final File cacheFile = new File(cacheDir, objectName); 

    try { 

     fos = new FileOutputStream(cacheFile); 
     oos = new ObjectOutputStream(fos); 
     oos.writeObject(obj); 
    } catch (Exception e) { 
     e.printStackTrace(); 

    } finally { 
     try { 
      if (oos != null) { 
       oos.close(); 
      } 
      if (fos != null) { 
       fos.close(); 
      } 

     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
    } 
    return true; 
} 

public boolean deleteObject() { 

    final File cacheDir = context.getCacheDir(); 
    final File cacheFile = new File(cacheDir, objectName); 
    return (cacheFile.delete()); 
} 

public Object getObject() { 

    final File cacheDir = context.getCacheDir(); 
    final File cacheFile = new File(cacheDir, objectName); 

    Object simpleClass = null; 
    FileInputStream fis = null; 
    ObjectInputStream is = null; 

    try { 

     fis = new FileInputStream(cacheFile); 
     is = new ObjectInputStream(fis); 
     simpleClass = (Object) is.readObject(); 
    } catch (Exception e) { 
     e.printStackTrace(); 

    } finally { 
     try { 
      if (fis != null) { 
       fis.close(); 
      } 
      if (is != null) { 
       is.close(); 
      } 

     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
    } 

    return simpleClass; 

} 
} 

而且從活動一開始對象類，保存它，retreive它像這樣

objectCache = new ObjectCache(this,"sessionCache2"); 
//save object returns true 
boolean result = objectCache.saveObject(s); 

//get object back 
Object o = objectCache.getObject(); 

，而不是對象OI需要的是一個Session對象，但隨後即將意味着getObject方法的返回類型需要返回該類型。我不能將對象轉換一些

Answer 1

如果您確信該ObjectCache將返回的對象是一個Session對象所有你需要做的就是投它：

//get object back 
Session session = (Session) objectCache.getObject(); 

，這將拋出一個ClassCastException（未選中）如果getObject()方法不返回Session對象。