android - FileNotFoundException 打开失败 : EACCES (Permission denied) on Android Emulator

Question

以下是 Activity 出错的代码:
错误发生在行 outputStream = new FileOutputStream(file);

public class MainActivity extends AppCompatActivity {

    public void layoutToJPG(View v) {
        View screen = v.getRootView();
// or I've also tried: View screen = new View(this);
        screen.setDrawingCacheEnabled(true);
        Bitmap b = screen.getDrawingCache();
        Log.d("bitmap", b.toString());
        File path = Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_MOVIES);
        File file = new File(path, "/sample.jpg");
        FileOutputStream outputStream = null;
        try {
            outputStream = new FileOutputStream(file);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        b.compress(Bitmap.CompressFormat.JPEG, 100, outputStream);
        Toast.makeText(getApplicationContext(), "Saved to Gallery.", Toast.LENGTH_SHORT).show();
        try {
            outputStream.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }
        try {
            outputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

错误 :

 W/libc: Unable to set property "qemu.gles" to "1": connection failed; errno=13 (Permission denied)

W/System.err: java.io.FileNotFoundException: /storage/emulated/0/Movies/sample.jpg: open failed: EACCES (Permission denied)
        at libcore.io.IoBridge.open(IoBridge.java:496)
        at java.io.FileOutputStream.<init>(FileOutputStream.java:235)

以上是我得到的错误。我在 android 模拟器上运行它 像素 XL API 29
在模拟器上保存文件是否需要一些特殊权限。

Answer 1

您必须添加权限。并且，要求用户接受许可。
显现 :

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

请求许可:
有一个 library你可以用它来请求许可

Dexter.withContext(this)
.withPermission(Manifest.permission.CAMERA)
.withListener(new PermissionListener() {
    @Override public void onPermissionGranted(PermissionGrantedResponse response) {/* ... */}
    @Override public void onPermissionDenied(PermissionDeniedResponse response) {/* ... */}
    @Override public void onPermissionRationaleShouldBeShown(PermissionRequest permission, PermissionToken token) {/* ... */}
}).check();

超过 API 级别 23(也许，我实际上忘记了)您必须请求用户授予权限。这就是为什么你必须添加上面的源代码。