无法在SD卡中创建文件

Question

我试图将位图保存到文件,然后将其保存在SD卡上.这是我的代码:

String path = Environment.getExternalStorageDirectory().toString();
File file = new File(path, "Jhs"+".jpg");
file.mkdir();
OutputStream fOut;
try {
    fOut = new FileOutputStream(file);
    BitmapMatrix convMatrix = new BitmapMatrix(0);
    convMatrix.result.compress(Bitmap.CompressFormat.JPEG, 100, fOut);

    fOut.flush();
    fOut.close();
} catch (FileNotFoundException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

此代码也在一个不扩展Activity的类中.我只是给出了这个信息,认为可能存在一些问题.这是我的LogCat

05-01 18:00:22.555: W/System.err(31392): java.io.FileNotFoundException:           /mnt/sdcard/Jhs.jpg (Permission denied)
05-01 18:00:22.555: W/System.err(31392):    at org.apache.harmony.luni.platform.OSFileSystem.open(Native Method)
05-01 18:00:22.555: W/System.err(31392):    at dalvik.system.BlockGuard$WrappedFileSystem.open(BlockGuard.java:232)
05-01 18:00:22.555: W/System.err(31392):    at java.io.FileOutputStream.<init>(FileOutputStream.java:94)
05-01 18:00:22.555: W/System.err(31392):    at java.io.FileOutputStream.<init>(FileOutputStream.java:66)
05-01 18:00:22.555: W/System.err(31392):    at com.example.imageprocess.BitmapMatrix.computeConvolution3x3(BitmapMatrix.java:123)
05-01 18:00:22.555: W/System.err(31392):    at com.example.imageprocess.MainActivity.sharpen(MainActivity.java:105)
05-01 18:00:22.555: W/System.err(31392):    at com.example.imageprocess.MainActivity.onCreate(MainActivity.java:51)
05-01 18:00:22.555: W/System.err(31392):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1072)
05-01 18:00:22.555: W/System.err(31392):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1836)
05-01 18:00:22.555: W/System.err(31392):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1893)
05-01 18:00:22.555: W/System.err(31392):    at android.app.ActivityThread.access$1500(ActivityThread.java:135)
05-01 18:00:22.555: W/System.err(31392):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1054)
05-01 18:00:22.555: W/System.err(31392):    at android.os.Handler.dispatchMessage(Handler.java:99)
05-01 18:00:22.565: W/System.err(31392):    at android.os.Looper.loop(Looper.java:150)
05-01 18:00:22.565: W/System.err(31392):    at android.app.ActivityThread.main(ActivityThread.java:4389)
05-01 18:00:22.565: W/System.err(31392):    at java.lang.reflect.Method.invokeNative(Native Method)
05-01 18:00:22.565: W/System.err(31392):    at java.lang.reflect.Method.invoke(Method.java:507)
05-01 18:00:22.565: W/System.err(31392):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:849)
05-01 18:00:22.565: W/System.err(31392):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:607)
05-01 18:00:22.565: W/System.err(31392):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

该logcat表示您无权编写该文件,请确保已声明

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

在android清单中.

你可以添加这个:

File dir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getPath()+ "/%YOUR_FOLDER%/");
if (!(dir.exists() && dir.isDirectory())) {
    dir.mkdirs();
}

如果您想为文件尝试不同的文件夹位置,请查看当前代码是否有用.代码将创建目录/ sdcard/Downloads/YOUR_FOLDER /,您可以在其中创建文件.请参阅此处了解存储位置选项.

然后你可以做

File file = new File(dir, "Jhs"+".jpg");
file.createNewFile(); //CREATE THE FILE FIRST!
OutputStream fOut;
try {
    fOut = new FileOutputStream(file);
    ....
}

等在你的帖子中.