你的问题的答案是你需要有权限。在manifest.xml文件中输入以下代码:

<uses-sdk  android:minSdkVersion="8"   android:targetSdkVersion="18" />
<uses-permission android:name="android.permission.READ_CONTACTS" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
<uses-permission android:name="android.permission.WRITE_OWNER_DATA"></uses-permission>
<uses-permission android:name="android.permission.READ_OWNER_DATA"></uses-permission>`

这对我很管用……

我在这里尝试了几个答案，我认为我有一个解决方案，每次都可以工作，并且还可以管理权限。

这是基于LEO的巧妙解决方案。这篇文章应该包含所有的代码，你需要使这个工作，它应该工作在任何手机和Android版本;)

为了能够从SD卡中选择文件，你需要在你的清单中这样做:

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

常量:

private static final int PICK_IMAGE = 456; // Whatever number you like
public static final int MY_PERMISSIONS_REQUEST_READ_EXTERNAL = 28528; // Whatever number you like
public static final String FILE_TEMP_NAME = "temp_image"; // Whatever file name you like

检查权限和launchImagePick如果可能的话

if (ContextCompat.checkSelfPermission(getThis(),
        Manifest.permission.READ_EXTERNAL_STORAGE)
        != PackageManager.PERMISSION_GRANTED) {

    ActivityCompat.requestPermissions(getThis(),
            new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
            MY_PERMISSIONS_REQUEST_READ_EXTERNAL);
}
else {
    launchImagePick();
}

允许响应

@Override
public void onRequestPermissionsResult(int requestCode,
                                       @NonNull
                                         String permissions[],
                                       @NonNull
                                         int[] grantResults) {

    if (manageReadExternalPermissionResponse(this, requestCode, grantResults)) {
        launchImagePick();
    }
}

管理权限响应

public static boolean manageReadExternalPermissionResponse(final Activity activity, int requestCode, int[] grantResults) {

    if (requestCode == MY_PERMISSIONS_REQUEST_READ_EXTERNAL) {

        // If request is cancelled, the result arrays are empty.

        if (grantResults.length > 0
                && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

            // Permission was granted, yay! Do the
            // contacts-related task you need to do.
            return true;

        } else if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_DENIED) {

            boolean showRationale = ActivityCompat.shouldShowRequestPermissionRationale(activity,
                    Manifest.permission.READ_EXTERNAL_STORAGE);

            if (!showRationale) {
                // The user also CHECKED "never ask again".
                // You can either enable some fall back,
                // disable features of your app
                // or open another dialog explaining
                // again the permission and directing to
                // the app setting.

            } else {
                // The user did NOT check "never ask again".
                // This is a good place to explain the user
                // why you need the permission and ask if he/she wants
                // to accept it (the rationale).
            }
        } else {
            // Permission denied, boo! Disable the
            // functionality that depends on this permission.
        }
    }
    return false;
}

发射图像选择

private void launchImagePick() {

    Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
    intent.setType("image/*");
    intent.addCategory(Intent.CATEGORY_OPENABLE);
    startActivityForResult(intent, PICK_IMAGE);

    // see onActivityResult
}

管理图像选择响应

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == PICK_IMAGE) {

        if (resultCode == Activity.RESULT_OK) {
            if (data != null && data.getData() != null) {

                try {
                     InputStream inputStream = getContentResolver().openInputStream(data.getData())
                     if (inputStream != null) {

                        // No special persmission needed to store the file like that
                        FileOutputStream fos = openFileOutput(FILE_TEMP_NAME, Context.MODE_PRIVATE);

                        final int BUFFER_SIZE = 1 << 10 << 3; // 8 KiB buffer
                        byte[] buffer = new byte[BUFFER_SIZE];
                        int bytesRead = -1;
                        while ((bytesRead = inputStream.read(buffer)) > -1) {
                            fos.write(buffer, 0, bytesRead);
                        }
                        inputStream.close();
                        fos.close();

                        File tempImageFile = new File(getFilesDir()+"/"+FILE_TEMP_NAME);

                        // Do whatever you want with the File

                        // Delete when not needed anymore
                        deleteFile(FILE_TEMP_NAME);
                    }
                }
                catch (Exception e) {
                    e.printStackTrace();
                }
            } else {
                // Error display
            }
        } else {
            // The user did not select any image
        }
    }
}

这就是所有的人;这在我所有的电话上都适用。

这是一个完全的hack，但这是我所做的…

因此，在设置DocumentsProvider时，我注意到样例代码(在getDocIdForFile中，大约在第450行)根据文件相对于指定根的路径(即在第96行中设置mBaseDir的路径)为所选文档生成了唯一的id。

所以URI最终看起来像这样:

内容:/ / com.example.provider /文档/根:路径/ / /文件

正如文档所说，它假设只有一个根(在我的情况下是Environment.getExternalStorageDirectory()，但你可以在其他地方使用…然后它获取文件路径，从根目录开始，并使其成为唯一的ID，前置“root:”。所以我可以通过消除uri.getPath()中的“/document/root:”部分来确定路径，通过这样做来创建一个实际的文件路径:

public void onActivityResult(int requestCode, int resultCode, Intent data) {
// check resultcodes and such, then...
uri = data.getData();
if (uri.getAuthority().equals("com.example.provider"))  {
    String path = Environment.getExternalStorageDirectory(0.toString()
                 .concat("/")
                 .concat(uri.getPath().substring("/document/root:".length())));
    doSomethingWithThePath(path); }
else {
    // another provider (maybe a cloud-based service such as GDrive)
    // created this uri.  So handle it, or don't.  You can allow specific
    // local filesystem providers, filter non-filesystem path results, etc.
}

我知道。这很可耻，但它奏效了。同样，这依赖于您在应用程序中使用自己的文档提供程序来生成文档ID。

(此外，还有一种更好的方法来构建路径，不假设“/”是路径分隔符，等等。但你懂的。)

对于那些仍然在Android SDK版本23及以上使用@Paul Burke的代码的人，如果你的项目遇到错误说你缺少EXTERNAL_PERMISSION，并且你非常确定你已经在AndroidManifest.xml文件中添加了user-permission。这是因为在Android API 23或以上和谷歌中，当您在运行时执行访问文件的操作时，有必要再次保证权限。

这意味着:如果你的SDK版本是23或以上，当你选择图片文件并想知道它的URI时，你会被要求读取和写入权限。

下面是我的代码，除了Paul Burke的解决方案。我添加这些代码，我的项目开始工作良好。

private static final int REQUEST_EXTERNAL_STORAGE = 1;
private static final String[] PERMISSINOS_STORAGE = {
    Manifest.permission.READ_EXTERNAL_STORAGE,
    Manifest.permission.WRITE_EXTERNAL_STORAGE
};

public static void verifyStoragePermissions(Activity activity) {
    int permission = ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE);

    if (permission != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(
                activity,
                PERMISSINOS_STORAGE,
                REQUEST_EXTERNAL_STORAGE
        );
    }
}

在你的activity&fragment请求URI的地方:

private void pickPhotoFromGallery() {

    CompatUtils.verifyStoragePermissions(this);
    Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
    intent.setType("image/*");
    // startActivityForResult(intent, REQUEST_PHOTO_LIBRARY);
    startActivityForResult(Intent.createChooser(intent, "选择照片"),
            REQUEST_PHOTO_LIBRARY);
}

在我的例子中，CompatUtils.java是我定义verifyStoragePermissions方法的地方(作为静态类型，所以我可以在其他活动中调用它)。

此外，如果在调用verifyStoragePermissions方法之前先设置一个if状态来查看当前SDK版本是否高于23，这应该更有意义。

有同样的问题，尝试上面的解决方案，但虽然它一般工作，由于某种原因，我得到了一些图像的Uri内容提供者的权限拒绝，尽管我有android.permission。MANAGE_DOCUMENTS权限添加正确。

不管怎样，找到了其他的解决方案，这是迫使打开图库，而不是KITKAT文档视图:

// KITKAT

i = new Intent(Intent.ACTION_PICK,android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
    startActivityForResult(i, CHOOSE_IMAGE_REQUEST);

然后加载图片:

Uri selectedImageURI = data.getData();
input = c.getContentResolver().openInputStream(selectedImageURI);
                BitmapFactory.decodeStream(input , null, opts);

EDIT

ACTION_OPEN_DOCUMENT可能需要你持久化权限标志等，通常会导致安全异常…

Other solution is to use the ACTION_GET_CONTENT combined with c.getContentResolver().openInputStream(selectedImageURI) which will work both on pre-KK and KK. Kitkat will use new documents view then and this solution will work with all apps like Photos, Gallery, File Explorer, Dropbox, Google Drive etc...) but remember that when using this solution you have to create image in your onActivityResult() and store it on SD Card for example. Recreating this image from saved uri on next app launch would throw Security Exception on content resolver even when you add permission flags as described in Google API docs (that's what happened when I did some testing)

此外，Android开发者API指南建议:

ACTION_OPEN_DOCUMENT is not intended to be a replacement for ACTION_GET_CONTENT. The one you should use depends on the needs of your app: Use ACTION_GET_CONTENT if you want your app to simply read/import data. With this approach, the app imports a copy of the data, such as an image file. Use ACTION_OPEN_DOCUMENT if you want your app to have long term, persistent access to documents owned by a document provider. An example would be a photo-editing app that lets users edit images stored in a document provider.

This is what I do: Uri selectedImageURI = data.getData(); imageFile = new File(getRealPathFromURI(selectedImageURI)); private String getRealPathFromURI(Uri contentURI) { Cursor cursor = getContentResolver().query(contentURI, null, null, null, null); if (cursor == null) { // Source is Dropbox or other similar local file path return contentURI.getPath(); } else { cursor.moveToFirst(); int idx = cursor.getColumnIndex(MediaStore.Images.ImageColumns.DATA); return cursor.getString(idx); } } NOTE: managedQuery() method is deprecated, so I am not using it.

这个答案是来自m3n0R的问题安卓得到真正的路径Uri.getPath()和我声称没有信用。我只是想那些还没有解决这个问题的人可以使用这个。