Question

您好我正在尝试在我的应用程序中导入数据库。但是它失败了，我收到了fileNotFountException。请帮我在我的应用程序中导入数据库。我的设备内存中我的数据库备份成功。为什么我get filenotfoundexception.I在dbname.db

中存储了我的db备份

  private void importDB() {
    try {
        File sd = Environment.getExternalStorageDirectory();
        File data = Environment.getDataDirectory();
        if (sd.canWrite()) {

            System.out.println("KKKKKKKKKKKKKKKKKKKKKK");
            String currentDBPath = "//data//" + getPackageName() + "//databases//" + "dbname.db" ;
            String backupDBPath = "Restore.db"; // From SD directory.

            System.out.println("HHHHHHHHHHHHHHHHHHHHHHH");
            File backupDB = new File(data, currentDBPath);
            File currentDB = new File(sd, backupDBPath);
            System.out.println("AAAAAAAAAAAAAAAAAAAAAAAAAaa");
            FileChannel src = new FileInputStream(backupDB).getChannel();
            FileChannel dst = new FileOutputStream(currentDB).getChannel();
            dst.transferFrom(src, 0, src.size());
            System.out.println("FFFFFFFFFFFFFFFFFFFFFFFFFFFFH");
            src.close();
            dst.close();
            Toast.makeText(getApplicationContext(), "Import Successful!",
                    Toast.LENGTH_SHORT).show();

        }
    } catch (Exception e) {

        Toast.makeText(getApplicationContext(), "Import Failed!", Toast.LENGTH_SHORT)
                .show();
        e.printStackTrace();

    }
}

我的例外

    java.io.FileNotFoundException: /data/data/com.example.rr.remainder/databases/dbname.db: open failed: ENOENT (No such file or directory)
09-22 06:02:36.486 21445-21445/com.example.rr.remainder W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:409)
09-22 06:02:36.486 21445-21445/com.example.rr.remainder W/System.err:     at java.io.FileInputStream.<init>(FileInputStream.java:78)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at com.example.rr.remainder.restore.importDB(restore.java:84)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at com.example.rr.remainder.restore.access$100(restore.java:15)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at com.example.rr.remainder.restore$2.onClick(restore.java:35)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at android.view.View.performClick(View.java:4741)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at android.view.View$PerformClick.run(View.java:19384)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at android.os.Handler.handleCallback(Handler.java:733)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:95)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at android.os.Looper.loop(Looper.java:146)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:5679)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at java.lang.reflect.Method.invokeNative(Native Method)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at java.lang.reflect.Method.invoke(Method.java:515)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at dalvik.system.NativeStart.main(Native Method)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err: Caused by: libcore.io.ErrnoException: open failed: ENOENT (No such file or directory)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at libcore.io.Posix.open(Native Method)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at libcore.io.BlockGuardOs.open(BlockGuardOs.java:110)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:393)
09-22 06:02:36.496 21445-21445/com.example.rr.remainder W/System.err:   ... 15 more

Answer 1

当您尝试创建＆＃34; dbname.db＆＃34; 文件时，看起来不存在子目录 / databases 。

考虑使用以下代码，该代码将自动在应用程序的沙箱中创建一个子目录（如果它尚不存在）：

public void copyBackupDb(){
    File subDirPath = mContext.getDir("databases", Context.MODE_PRIVATE);
    File currentDBFile = new File(subDirPath , "dbname.db");

    File sd = Environment.getExternalStorageDirectory();
    File backupDBFile = new File(sd,"Restore.db");

    try {
        copy(backupDBFile, currentDBFile);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

public static void copy(File src, File dst) throws IOException {
    try (InputStream in = new FileInputStream(src)) {
        try (OutputStream out = new FileOutputStream(dst)) {
            // Transfer bytes from in to out
            byte[] buf = new byte[1024];
            int len;
            while ((len = in.read(buf)) > 0) {
                out.write(buf, 0, len);
            }
        }
    }
}

* mContext是Andriod活动或服务的上下文参考。

在android应用程序中导入db

1 个答案: