chmod失败：android中的EPERM(不允许操作)？

我想在sdcard或外部SD卡中创建数据库为此我已经尝试了这个代码并使用这个我已经在SD卡中成功创建了数据库,但在logcat中它给了我如下警告

logcat的

07-18 14:18:22.140: W/FileUtils(8595): Failed to
chmod(/mnt/sdcard/peakmedia/DB_PMD): libcore.io.ErrnoException: chmod
failed: EPERM (Operation not permitted)

DB_Helper.java

public class DB_Helper extends SQLiteOpenHelper
{

    public DB_Helper(Context context) 
    {   
        super(context, Environment.getExternalStorageDirectory().getAbsolutePath() 
                       + File.separator + DB_Constant.DB.FILE_DIR 
                       + File.separator + DB_Constant.DB.DATABASENAME, null, DB_Constant.DB.DB_VERSION);

    }

    @Override
    public void onCreate(SQLiteDatabase db) 
    {
        String  query=String.format(DB_Constant.CREATE_TABLE_QUERY.CREATE_MYFILES_TABLE);
        db.execSQL(query);


        query=String.format(DB_Constant.CREATE_TABLE_QUERY.CREATE_MYUSERS_TABLE);
        db.execSQL(query);

        query=String.format(DB_Constant.CREATE_TABLE_QUERY.CREATE_MYPLAYLIST_TABLE);
        db.execSQL(query);

        query=String.format(DB_Constant.CREATE_TABLE_QUERY.CREATE_MYDEVICE_TABLE);
        db.execSQL(query);

    }

     @Override
     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) 
     {
            if(newVersion > oldVersion)
            {   

                db.execSQL("DROP TABLE IF EXISTS "+ DB_Constant.TABLE.MYFILES);
                onCreate(db);

                db.execSQL("DROP TABLE IF EXISTS "+ DB_Constant.TABLE.MYUSERS);
                onCreate(db);

                db.execSQL("DROP TABLE IF EXISTS "+ DB_Constant.TABLE.MYPLAYLIST);
                onCreate(db);

                db.execSQL("DROP TABLE IF EXISTS "+ DB_Constant.TABLE.MYDEVICE);
                onCreate(db);

            }
     }
}

解决方法:

刚刚解决了这个问题.

你必须让你的应用程序加入linux build以授予它SYSTEM权限.

>将此行添加到Android.mk中

LOCAL_CERTIFICATE：=平台
>将其添加到AndroidManifest.xml的清单节点中

机器人：sharedUserId = “android.uid.system”
>生成apk并将其推入/ system / app /
>现在你可以试着跑了

final String command = "chmod 777 /data/ena";
Process p = Runtime.getRuntime().exec(command);

要么

File file = new File("/data/ena");
if (file.exists()) {
    boolean result = file.setExecutable(true);
    Log.e(TAG, "trpb67, RESULT IS " + result);
}

结果的值应该是真的

标签：android,android-sqlite
来源： https://codeday.me/bug/20191006/1858050.html