Android路径内部存储

Question

File sd = Environment.getExternalStorageDirectory();
            File data = Environment.getDataDirectory();
           FileChannel source=null;
           FileChannel destination=null;
           String cartella = (getString(R.string.app_name));
           String currentDBPath = "/data/"+getPackageName()+"/cartella/"+"Backup.db";
           String backupDBPath = "/cartella/Backup.db";

           File currentDB = new File(data, currentDBPath);
           File backupDB = new File(sd, backupDBPath);
           try {
                source = new FileInputStream(currentDB).getChannel();
                destination = new FileOutputStream(backupDB).getChannel();
                destination.transferFrom(source, 0, source.size());
                source.close();
                destination.close();
                Toast.makeText(this, "DB Exported!", Toast.LENGTH_LONG).show();
            } catch(IOException e) {
                e.printStackTrace();
                  Toast toast = Toast.makeText(getApplicationContext(),(R.string.Toast_export_errore), Toast.LENGTH_SHORT);
                     toast.show();

01-20 08:55:14.757: W/System.err(1383): java.io.FileNotFoundException: /data/data/info.androidhive.slidingmenu/cartella/Backup.db: open failed: ENOENT (No such file or directory)

01-20 08:55:14.787:W/System.err(1383):at libcore.io.iobridge.open(iobridge.java:409)01-20 08:55:14.787:W/System.err(1383):at java.io.fileInputStream.（fileInputstream.java:78)01-20 08:55:14.827:W/System.err(1383):at main.impostazioni.esporta（impostazioni.java:334)01-20 2008:55:14.827:W/System.err(1383):at java.lang.reflect.Method.invoke(Method.java:525)01-2008:55:14.827:W/System.err(1383):at Android.view.view.view$1.onclick(View.java:3628)01-2008:55:14.857:W/System.err(1383):at Android.view.view.performClick(View.java:4240)01-2008:55:14.857:W/System.err(1383):at 55:14.877:W/System.err(1383):at Android.os.handler.handleCallback（handler.java：730）01-20 08:55:14.877:W/System.err(1383):at Android.os.handler.dispatchMessage（handler.java：92）01-20 08:55:14.887:W/System.err(1383):at Android.os.looper.loop（looper.java：730）137）01-20 08:55:14.898:W/System.err(1383):at android.app.activitythread.main(activitythread.java:5103)01-20 08:55:14.927:W/System.err(1383):at java.lang.reflect.Method.invokenative（本机方法）01-20 08:55:14.927:W/System.err(1383):at java.lang.reflect.Method.invoke(525)01-20 08:55:14.957:W/System.err(1383):at scaller.run(zygoteinit.java:737)01-20 08:55:14.957:W/system.err(1383):at com.android.internal.os.zygoteinit.main(zygoteinit.java:553)01-20 08:55:14.987:W/system.err(1383):at dalvik.system.nativestart.main（本机方法）01-20 08:55:14.987:W/system.err(1383):by：libcore.io.errnoexception：open failed：ENOENT

Answer 1

尝试替换：

File currentDB = new File(data, currentDBPath);

与：

File currentDB = getDatabasePath("Backup.db");

硬编码数据库路径不是一个好主意，因为它不能保证在所有设备上都是相同的。使用getDatabasePath（）将返回创建数据库的路径。因此，如果数据库确实存在，将返回正确的路径。

source = new FileInputStream(backupDB).getChannel();
destination = new FileOutputStream(currentDB).getChannel();