File緩存的進級實踐

將數據緩存到file中，便於下次恢復數據，或者預先加載。

Cache管理類： ObjectOutputStream及Serializable 的api，，自行查看 java文檔

public class CacheManager {

public static CacheManager mInstance;

static {
	mInstance = new CacheManager();  //單例
}
private CacheManager() {
}
public <T> T readCacheFile(Context context, T t, String fileName) {
	ObjectInputStream in = null;
	try {
		File file = new File(context.getCacheDir(), fileName);
		if (!file.exists()) {
			return null;
		}
                                           //下步操做，也能夠用android 中context對象來獲取 流
		FileInputStream file_in = new FileInputStream(file);
		in = new ObjectInputStream(file_in);
		t = (T) in.readObject();
		return t;
	} catch (Exception e) {
		e.printStackTrace();
		return null;
	} finally {
		if (in != null) {
			try {
				in.close();
			} catch (Exception e2) {
				e2.printStackTrace();
			}

		}
	}

}

/*
 * mClass 必須實現Serializable ObjectOutputStream 用於序列號對象
 */
public <T> void writeCacheFile(Context context, T mClass, String fileName) {

	ObjectOutputStream out = null;
	try {
		File file = new File(context.getCacheDir(), fileName);
		if (file.exists()) {
			file.delete();
		}
		file.createNewFile();
		FileOutputStream file_out = new FileOutputStream(file);
		out = new ObjectOutputStream(file_out);
		out.writeObject(mClass);
	} catch (Exception e) {
		e.printStackTrace();
	} finally {
		if (out != null) {
			try {
				out.close();
			} catch (Exception e2) {
				e2.printStackTrace();
			}
		}
	}
}

}

注意點：單例操做類中不要傳入Actiivty的引用，以避免形成activity回收不了，最好傳入applicationcontext