PROSAGA码农传奇-数据隔离-服务和Singleton SQliteOpenHelper进行数据隔离

服务和Singleton SQliteOpenHelper进行数据隔离

作者: 只怕再见是故人
发布时间: 2024-05-23 11:01:53 (1月前)

我已经用Singleton模式实现了SQliteOpenHelper，并且到目前为止工作正常。但是请考虑以下顺序：片段启动事务以更新记录 触发了服务，该服务读取更新的数据 事务由于某种原因失败并被回滚 该服务将处理未提交的数据，这些数据稍后会回滚。因此，似乎单例模式与服务结合会导致数据隔离问题。但是我读了很多推荐单身人士的文章。使用单例时如何处理这种情况？
<pre><code>public class MyApplication extends Application{
 private static MyApplication instance;
 public MyApplication(){
 instance = this;
 }
 public static Context getContext(){
 return instance;
 }
}

public class LocalDBHelper extends SQLiteOpenHelper{
    private static final int DATABASE_VERSION = 1;
    private static final String DATABASE_NAME = "MyDB";
    private static final String LOG_TAG = "LocalDBHelper";

private static LocalDBHelper instance = null;
 /*private constructor to avoid direct instantiation by other classes*/
 private LocalDBHelper(){
 super(MyApplication.getContext(), DATABASE_NAME, null, DATABASE_VERSION);
 }
 /*synchronized method to ensure only 1 instance of LocalDBHelper exists*/
 public static synchronized LocalDBHelper getInstance(){
 if(instance == null){
 instance = new LocalDBHelper();
 }
 return instance;
 }
 ...
 ...
}
</code></pre>交易用途：
<pre><code>SQLiteDatabase db = LocalDBHelper.getInstance().getWritableDatabase();
db.beginTransaction();
try{
....
...
db.setTransactionSuccessful();
}catch(Exception e){
 e.printStackTrace();
}
finally{
 db.endTransaction();
}
</code></pre>