哪裏可以創建業務邏輯對象並保持狀態？

我的應用程序依賴於Android獨立類的核心模塊來執行業務邏輯。這些對象需要可用於應用程序的所有部分，並且還需要在整個應用程序中保持其狀態。哪裏可以創建業務邏輯對象並保持狀態？

我一直在應用程序子類中實例化這些對象，並在我的活動和服務中使用它們。但是，當Android決定終止我的應用程序以釋放內存時，這些業務邏輯對象也會被終止並失去它們的狀態。

Android應用程序中有狀態業務對象模型的最佳策略是什麼？

來源

2014-11-14 Lance Hardwood

創建一個類並將其序列化並保存到共享首選項或任何其他由android提供的存儲選項。 –

它更好地提取您的關鍵對象的所有屬性，並將它們轉儲到持久存儲中，例如android中的「SharedPreferences」，下一次當您的應用程序重新啓動時，重新從這些值啓動您的對象。 – Techfist

請記住，在'SharedPreferences'中，您只能存儲像'boolean，float，int，long，String'等值的原語。 – Mayank

如果要在用戶關閉應用程序時保存它們，則必須將它們保存在共享首選項或數據庫或手機內存中的文件中！和用於內部應用，可以簡單地在從Serializable或Parcelable延伸的類定義它們，並將它們傳遞活動/片段之間的/ etc

來源

2014-11-14 07:30:49

此完美解決方案是使用持久性存儲。我遵循的是有點複雜但非常有用。它在三個部分被劃分：

SQLite數據庫
API助手
Singleton類（數據助手）

和以下步驟：

檢索的所有數據db到單個實例類。
每當我需要更新它，然後在課堂上更新。
在某些特定事件中將其轉儲到數據庫中。（如按鈕點擊或後按）。

通過這種方式，你有你的數據的完整和容易獲得通過在應用軟件

數據庫：不再詳述了。它可以是任何持久性存儲，如數據庫或首選項。

API幫助程序：示例api幫助程序類。取決於您的存儲空間，它可以是任何東西。

public class AppsApi {  
private static AppsApi appInstance; 
private Context mContext; 

public static AppsApi getInstance(Context context) { 

    if (appInstance == null) 
     appInstance = new AppsApi(context); 
    return appInstance; 

} 

public AppsApi(Context context) { 
    this.mContext = context; 
} 

public static String PROJECTION[]; 

static { 
    String[] arrayOfString = new String[5]; 
    arrayOfString[0] = AppsTable.COLUMN_ID; 
    arrayOfString[1] = AppsTable.COLUMN_APP_NAME; 
    arrayOfString[2] = AppsTable.COLUMN_APP_PACKAGE_NAME; 
    arrayOfString[3] = AppsTable.COLUMN_APP_ACTIVITY_NAME; 
    arrayOfString[4] = AppsTable.COLUMN_IS_FROM_DASHBOARD; 
    PROJECTION = arrayOfString; 
} 

public int insertApp(ContentValues app) { 

    Uri uri = mContext.getContentResolver().insert(
      DashDroidContentProvider.CONTENT_URI_APP, app); 
    System.out.println("APP Added URI :: " + uri); 
    return Integer.parseInt(uri.getLastPathSegment()); 

} 

public Cursor getAllApps() { 
    return mContext.getContentResolver().query(
      DashDroidContentProvider.CONTENT_URI_APP, AppsApi.PROJECTION, 
      null, null, null); 
} 

public Cursor getAllApp(boolean isFromDashBoard) { 
    int is = isFromDashBoard ? 1 : 0; 
    return mContext.getContentResolver().query(
      DashDroidContentProvider.CONTENT_URI_APP, AppsApi.PROJECTION, 
      AppsTable.COLUMN_IS_FROM_DASHBOARD + " LIKE ?", 
      new String[] { is + "" }, null); 
} 

public void deleteApp(int id) { 
    mContext.getContentResolver().delete(
      DashDroidContentProvider.CONTENT_URI_APP, 
      AppsTable.COLUMN_ID + " = ?", new String[] { id + "" }); 
} 

public void deleteApp(String packageName) { 
    mContext.getContentResolver().delete(
      DashDroidContentProvider.CONTENT_URI_APP, 
      AppsTable.COLUMN_APP_PACKAGE_NAME + " LIKE ?", 
      new String[] { packageName + "" }); 
} 

public void updateApp(ContentValues app, int id) { 
    int uri = mContext.getContentResolver().update(
      DashDroidContentProvider.CONTENT_URI_APP, app, "_id=?", 
      new String[] { id + "" }); 
    System.out.println("App Updated URI ::" + uri); 
} 

public void clear() { 
    mContext.getContentResolver().delete(
      DashDroidContentProvider.CONTENT_URI_APP, null, null); 
} 

public int count() { 
    return ((Cursor) mContext.getContentResolver().query(
      DashDroidContentProvider.CONTENT_URI_APP, 
      new String[] { AppsTable.COLUMN_ID }, null, null, null)) 
      .getCount(); 
} 

public Cursor filterApp(String selection, String[] selectionArgs) { 

    return mContext.getContentResolver().query(
      DashDroidContentProvider.CONTENT_URI_APP, AppsApi.PROJECTION, 
      selection, selectionArgs, null); 
} 

public int insertBulkApps(ContentValues[] apps) { 

    int noOfRecordInserted = mContext.getContentResolver().bulkInsert(
      DashDroidContentProvider.CONTENT_URI_APP, apps); 
    System.out.println("Inserted Record Count :: " + noOfRecordInserted); 
    return noOfRecordInserted; 

}

}

數據助手：它是一個單實例類。通過應用程序爲您提供數據。這是巨大而簡單的。

public class AppsHelper { 

public static final int TYPE_SAVE = 0; 
public static final int TYPE_GET = 1; 
public static final int TYPE_UPDATE = 2; 

private AppsData[] appsDashBoard; 
private AppsData[] appsMoreApps; 

private AppsApi appsProvider; 

private OnDataBaseUpdateListener mListener; 

private static AppsHelper mHelper; 

public AppsHelper(Context context) { 
    appsProvider = AppsApi.getInstance(context); 
    initData(); 
    if (appsProvider.count() == 0) { 
     new saveDataTask().execute(); 
    } else { 
     updateAppsFromDatabase(); 
    } 

} 

public static AppsHelper getInstance(Context context) { 

    if (mHelper == null) 
     mHelper = new AppsHelper(context); 

    return mHelper; 

} 

private void initData() { 

    appsDashBoard = new AppsData[DashDroidConstants.NO_OF_DASH_BOARD_APPS]; 
    appsMoreApps = new AppsData[DashDroidConstants.NO_OF_MORE_APPS]; 

    for (int i = 0; i < appsDashBoard.length; i++) { 
     appsDashBoard[i] = new AppsData(i, "null", "null", "null"); 
    } 

    for (int i = appsDashBoard.length; i < (appsMoreApps.length + appsDashBoard.length); i++) { 
     appsMoreApps[i - appsDashBoard.length] = new AppsData(i, "null", 
       "null", "null"); 
    } 

} 

public void updateMoreApp(String appName, String activityName, 
     String appPackageName, int index) { 
    appsMoreApps[index].setData(appName, activityName, appPackageName); 
    new updateDataTask(false, index).execute(); 
} 

public void updateMoreApp(String appName, String activityName, 
     String appPackageName, int index, OnDataBaseUpdateListener listener) { 
    appsMoreApps[index].setData(appName, activityName, appPackageName); 
    this.mListener = listener; 
    new updateDataTask(false, index).execute(); 
} 

public void updateDashBoardApp(String appName, String activityName, 
     String appPackageName, int index) { 
    appsDashBoard[index].setData(appName, activityName, appPackageName); 
    new updateDataTask(true, index).execute(); 
} 

public void updateDashBoardApp(String appName, String activityName, 
     String appPackageName, int index, OnDataBaseUpdateListener listener) { 
    appsDashBoard[index].setData(appName, activityName, appPackageName); 
    this.mListener = listener; 
    new updateDataTask(true, index).execute(); 
} 

public void updateAppsFromDatabase() { 
    new getDataTask().execute(); 
} 

public AppsData[] getDashBoardApps() { 
    return appsDashBoard; 
} 

public AppsData[] getMoreApps() { 
    return appsMoreApps; 
} 

private void updateAppInDatabase(boolean isDashBoardApp, int index) { 
    ContentValues cv = new ContentValues(); 
    cv = new ContentValues(); 
    if (isDashBoardApp) { 
     cv.put(AppsTable.COLUMN_APP_PACKAGE_NAME, 
       appsDashBoard[index].getPackageName()); 
     cv.put(AppsTable.COLUMN_APP_ACTIVITY_NAME, 
       appsDashBoard[index].getActivityName()); 
     cv.put(AppsTable.COLUMN_APP_NAME, appsDashBoard[index].getAppName()); 
    } else { 
     cv.put(AppsTable.COLUMN_APP_PACKAGE_NAME, 
       appsMoreApps[index].getPackageName()); 
     cv.put(AppsTable.COLUMN_APP_ACTIVITY_NAME, 
       appsMoreApps[index].getActivityName()); 
     cv.put(AppsTable.COLUMN_APP_NAME, appsMoreApps[index].getAppName()); 
    } 

    int dbIndex = isDashBoardApp ? index : index + appsDashBoard.length; 
    appsProvider.updateApp(cv, dbIndex); 

} 

private int saveDataInDatabase() { 
    ContentValues[] cv = new ContentValues[appsDashBoard.length 
      + appsMoreApps.length]; 

    for (int i = 0; i < appsDashBoard.length; i++) { 
     cv[i] = new ContentValues(); 
     cv[i].put(AppsTable.COLUMN_ID, appsDashBoard[i].getId()); 
     cv[i].put(AppsTable.COLUMN_APP_PACKAGE_NAME, 
       appsDashBoard[i].getPackageName()); 
     cv[i].put(AppsTable.COLUMN_APP_ACTIVITY_NAME, 
       appsDashBoard[i].getActivityName()); 
     cv[i].put(AppsTable.COLUMN_APP_NAME, appsDashBoard[i].getAppName()); 
     cv[i].put(AppsTable.COLUMN_IS_FROM_DASHBOARD, "1"); 
    } 

    for (int i = appsDashBoard.length; i < (appsMoreApps.length + appsDashBoard.length); i++) { 
     cv[i] = new ContentValues(); 
     cv[i].put(AppsTable.COLUMN_ID, appsMoreApps[i 
       - appsDashBoard.length].getId()); 
     cv[i].put(AppsTable.COLUMN_APP_PACKAGE_NAME, appsMoreApps[i 
       - appsDashBoard.length].getPackageName()); 
     cv[i].put(AppsTable.COLUMN_APP_ACTIVITY_NAME, appsMoreApps[i 
       - appsDashBoard.length].getActivityName()); 
     cv[i].put(AppsTable.COLUMN_APP_NAME, appsMoreApps[i 
       - appsDashBoard.length].getAppName()); 
     cv[i].put(AppsTable.COLUMN_IS_FROM_DASHBOARD, "0"); 
    } 
    return appsProvider.insertBulkApps(cv); 
} 

private void getDataFromDatabase() { 

    Cursor appCursor = appsProvider.getAllApps(); 
    appCursor.moveToFirst(); 

    for (int i = 0; i < appsDashBoard.length; i++) { 
     appsDashBoard[i] 
       .setData(
         appCursor.getString(appCursor 
           .getColumnIndex(AppsTable.COLUMN_APP_NAME)), 
         appCursor.getString(appCursor 
           .getColumnIndex(AppsTable.COLUMN_APP_ACTIVITY_NAME)), 
         appCursor.getString(appCursor 
           .getColumnIndex(AppsTable.COLUMN_APP_PACKAGE_NAME))); 
     appCursor.moveToNext(); 
    } 

    for (int i = 0; i < appsMoreApps.length; i++) { 
     appsMoreApps[i] 
       .setData(
         appCursor.getString(appCursor 
           .getColumnIndex(AppsTable.COLUMN_APP_NAME)), 
         appCursor.getString(appCursor 
           .getColumnIndex(AppsTable.COLUMN_APP_ACTIVITY_NAME)), 
         appCursor.getString(appCursor 
           .getColumnIndex(AppsTable.COLUMN_APP_PACKAGE_NAME))); 
     appCursor.moveToNext(); 
    } 
} 

private class saveDataTask extends AsyncTask<Void, Void, Integer> { 

    @Override 
    protected Integer doInBackground(Void... params) { 
     return saveDataInDatabase(); 
    } 

    @Override 
    protected void onPostExecute(Integer result) { 

     if (mListener != null) 
      mListener.onDataUpdate(TYPE_SAVE); 
     super.onPostExecute(result); 
    } 

} 

private class getDataTask extends AsyncTask<Void, Void, Void> { 

    @Override 
    protected Void doInBackground(Void... params) { 
     getDataFromDatabase(); 
     return null; 
    } 

    @Override 
    protected void onPostExecute(Void result) { 
     if (mListener != null) 
      mListener.onDataUpdate(TYPE_GET); 
     super.onPostExecute(result); 
    } 
} 

private class updateDataTask extends AsyncTask<Void, Void, Void> { 

    boolean isFromDashBoard; 
    int index; 

    public updateDataTask(boolean isFromDashBoard, int index) { 
     this.isFromDashBoard = isFromDashBoard; 
     this.index = index; 

    } 

    @Override 
    protected Void doInBackground(Void... params) { 
     updateAppInDatabase(isFromDashBoard, index); 
     return null; 
    } 

    @Override 
    protected void onPostExecute(Void result) { 
     if (mListener != null) 
      mListener.onDataUpdate(TYPE_UPDATE); 
     super.onPostExecute(result); 
    } 
} 

public static class AppsData { 
    int id; 
    String appName; 
    String activityName; 
    String packageName; 

    public AppsData(int id, String appName, String activityName, 
      String packageName) { 
     this.id = id; 
     this.appName = appName; 
     this.activityName = activityName; 
     this.packageName = packageName; 
    } 

    public void setData(String appName, String activityName, 
      String packageName) { 
     this.appName = appName; 
     this.activityName = activityName; 
     this.packageName = packageName; 
    } 

    public int getId() { 
     return id; 
    } 

    public String getAppName() { 
     return appName; 
    } 

    public String getPackageName() { 
     return packageName; 
    } 

    public String getActivityName() { 
     return activityName; 
    } 
} 

public interface OnDataBaseUpdateListener { 
    public void onDataUpdate(int updateType); 
} 
}

它可以幫助您創建一個更有條理的代碼，並始終可用的數據，只需要調用AppsHelper.getInstance(context)和繁榮!!! :)

來源

2014-11-14 07:35:28

哪裏可以創建業務邏輯對象並保持狀態？

回答

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