android - chmod 失败 : EPERM (Operation not permitted) in android?

Question

我想为此在 sdcard 或外部 sdcard 中创建数据库我已经尝试过这段代码并使用它我已经成功地在 sdcard 中创建了数据库但是在 logcat 中它给我如下警告

逻辑猫

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);

            }
     }
}

Answer 1

刚刚解决了这个问题。

您必须让您的应用程序加入 linux build 才能授予它 SYSTEM 权限。

1. 将这一行添加到Android.mk

   LOCAL_CERTIFICATE := 平台

2. 将其添加到 AndroidManifest.xml 的 list 节点中

   android:sharedUserId="android.uid.system"

3. 生成apk并推送到/system/app/

4. 现在你可以试试跑

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

   或

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

   结果的值应该为真