本篇主要對Android調用系統相機裁剪及適配Android N的總結,不習慣簡書代碼風格的,也可以在 Android_Note查看.

系統相機相冊獲取圖片并裁剪Android N適配

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啟動相機相冊裁剪的隱式意圖

調用系統的拍照,相冊選取圖片并裁剪,一般使用系統的自帶隱式意圖Intent實現:

• 拍照 MediaStore.ACTION_IMAGE_CAPTURE

    public static final java.lang.String ACTION_IMAGE_CAPTURE = "android.media.action.IMAGE_CAPTURE"

• 啟動相冊:Intent.ACTION_GET_CONTENT

    public static final java.lang.String ACTION_GET_CONTENT = "android.intent.action.GET_CONTENT"

• 啟動裁剪: com.android.camera.action.CROP
  使用裁剪的功能通過intent.putExtra("key","value")實現.

關于return-data和MediaStore.EXTRA_OUTPUT:

• return data: 是將結果保存在data中,在onActivityResult時,直接調用intent.getdata()可得到,這里設置設置為false,即不保存在data中.

• MediaStore.EXTRA_OUTPUT:拍照生成的圖片由于沒有保存在data,需要有個地方保存圖片,而這key-value就是指圖片保存的URO地址.

注意: return-data如果設置為true,對應有些手機只會得到縮略圖,一般設置為false,一直用URI來輸出.而URI在有些手機上也會有問題.

• 權限:在Android6.0以上要檢查權限是否授予:

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

關于Android7.0 StrictMode政策

請參考: Android7.0適配心得

權限更改:

由于隨著Android版本越來越高,Android對用戶隱私保護力度越來越大,從Android6.0引入動態權限控制(Runtime Permission)到Android7.0私有目錄被限制訪問,"StrictMode API政策".由于之前Android版本中,是可以讀取到手機存儲中任何一個目錄及文件,這帶來很多安全問題.在Android7.0中為了提高私有文件的安全性.面向Android N或者更高版本將被限制訪問.

目錄限制被訪問

在Android7.0中為了提高私有文件的安全性，面向 Android N 或更高版本的應用私有目錄將被限制訪問。

• 私有文件的文件權限不再放權給所有的應用,使用MODE_WORLD_READABLE或者MODE_WORLD_WRITEABLE進行操作觸發SecurityException.這使得無法通過File API訪問手機存儲上的數據了,基于File API的一些文件瀏覽器也將受到很大影響.

• 給其他應用傳遞file://URI類型的Uri,可能會導致接收者無法訪問該路徑,因為在Android7.0中傳遞file://URI會觸發FileUriExposedException.可以通過FileProvider來解決.

• DownloadManager不再按文件名分享私人存儲的文件,COLUMN_LOCAL_FILENAME在Android7.0中標記為deprecate,舊版應用在訪問COLUMN_LOCAL_FILENAME可能會出現無法訪問的路徑.面向Android N或者更高版本中應用嘗試訪問COLUMN_LOCAL_FILENAME時會觸發SecurityException.但可以通過ContentResolver.openFileDescriptor()來訪問DownloadManager公開的文件.

拍照獲取圖片URI:

在Android7.0之前拍照,并獲取圖片URI如下:

    private void takePictureFromCamera() {
        //采用時間戳命名圖片名稱,不至于圖片名稱重復
        String pictureName = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss", Locale.getDefault()).format(new Date()) +
                "-" + System.currentTimeMillis() + ".jpg";
        mOutputImage = new File(getExternalCacheDir(), pictureName);
        imageUri = Uri.fromFile(mOutputImage);
        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri); //圖片存儲的地方.
        intent.putExtra("return-data", false);
        intent.putExtra("outputFormat", Bitmap.CompressFormat.JPEG.toString());
        intent.putExtra("noFaceDetection", true);
        ComponentName componentName = intent.resolveActivity(getPackageManager());
        if (componentName != null) {
            startActivityForResult(intent, REQUEST_CAPTURE);
        }
    }

但是在Android7.0(API24)上會報以下錯誤:

    android.os.FileUriExposedException: file:///storage/emulated/0/Android/data/com.showdy.androiddemo/cache/2016-12-30-10-25-55-1483064755273.jpg exposed beyond app through Intent.getData()
    at android.os.StrictMode.onFileUriExposed(StrictMode.java:1799)
    at android.net.Uri.checkFileUriExposed(Uri.java:2346)
    at android.content.Intent.prepareToLeaveProcess(Intent.java:8933)
    at android.content.Intent.prepareToLeaveProcess(Intent.java:8894)
    at android.app.Instrumentation.execStartActivity(Instrumentation.java:1517)
    at android.app.Activity.startActivityForResult(Activity.java:4223)
    ...
    at android.app.Activity.startActivityForResult(Activity.java:4182)

導致這崩潰的原因,就是Andorid N的 StrictMode 政策,但是我可以使用FileProvider來解決問題:使用步驟如下，

參考：file:// scheme is now not allowed to be attached with Intent on targetSdkVersion 24 (Android Nougat). And here is the solution.

• 清單文件中注冊provider

    <provider
        android:name="android.support.v4.content.FileProvider"
        android:authorities="${applicationId}.fileprovider"
        android:grantUriPermissions="true"
        android:exported="false">
        <meta-data
            android:name="android.support.FILE_PROVIDER_PATHS"
            android:resource="@xml/file_paths" />
    </provider>

exported:要求必須為false，為true則會報安全異常。

    Java.lang.RuntimeException: Unable to get provider Android.support.v4.content.FileProvider: Java.lang.SecurityException: Provider must not be exported）。

grantUriPermissions:true，表示授予 URI 臨時訪問權限。

• 指定共享目錄:

為了指定共享的目錄需要在res目錄下創建一個xml目錄,然后配置file_paths(名字隨意):

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <paths>
       <external-path  name="images" path="" />
    </paths>
</resources>

path的可選配置如下:

    <files-path name="name" path="path" /> //相當 Context.getFilesDir() + path, name是分享url的一部分
    
<cache-path name="name" path="path" /> //getCacheDir()
    
external-path name="name" path="path" /> //Environment.getExternalStorageDirectory()
    
<external-files-path name="name" path="path" />//getExternalFilesDir(String) Context.getExternalFilesDir(null)
    
<external-cache-path name="name" path="path" /> //Context.getExternalCacheDir()

其中path="",代表根目錄,如果是path="images",表示可以向其他應用共享根目錄以及其子目錄的任何文件. 則表示目錄名為:/storage/emulated/0/images,如果你向其他應用分享images目錄范圍之外的文件是不行.

• 使用FileProvider:

上面拍照代碼中指定了圖片存儲的imageUri為:imageUri=Uri.fromFile(mOutputImage);如果是Androd N(7.0)以上,imageUri的計算應該如下:

    imageUri= imageUri = FileProvider.getUriForFile(this, BuildConfig.APPLICATION_ID + ".provider", mOutputImage);
    //來對目標應用臨時授權該Uri所代表的文件。
intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);

通過FileProviderde得到文件的路徑得到文件的路徑:

content://com.showdy.androiddemo.provider/name/Android/data/com.showdy.androiddemo/cache/2016-12-30-10-25-55-1483064755273.jpg

而我們path設置為path="",這個content類型的Uri映射的File路徑就為:

/storage/emulated/0/Android/data/com.showdy.androiddemo/cache/2016-12-30-10-25-55-1483064755273.jpg

綜合前面所述Android7.0Strict Mode政策問題,拍照的功能獲取圖片Uri的方法(當然配置文件也是需要的)就如下:

     private void takePictureFromCamera() {

        String pictureName = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss", Locale.getDefault()).format(new Date()) +
                "-" + System.currentTimeMillis() + ".jpg";

        mOutputImage = new File(getExternalCacheDir(), pictureName);

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            imageUri = FileProvider.getUriForFile(this, BuildConfig.APPLICATION_ID + ".provider", mOutputImage);

            Log.e(TAG,imageUri.getPath());
        } else {
            imageUri = Uri.fromFile(mOutputImage);
        }

        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
        intent.putExtra("return-data", false);
        intent.putExtra("outputFormat", Bitmap.CompressFormat.JPEG.toString());
        intent.putExtra("noFaceDetection", true);
        ComponentName componentName = intent.resolveActivity(getPackageManager());
        if (componentName != null) {
            startActivityForResult(intent, REQUEST_CAPTURE);
        }
    }

那么在onActivityResult()方法就能將imageUri拿到,并設置給ImageView了.

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode != RESULT_OK) {
            return;
        }
        switch (requestCode) {
            case REQUEST_CAPTURE: // 拍照
                try {
                    Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));
                    mImageView.setImageBitmap(bitmap);
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                }
        }
    }

獲取系統相冊圖片

打開系統相冊隱式方式很簡單:

    //使用隱式意圖打開系統相冊
    private void takePictureFromAlum() {
        Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
        intent.setType("image/*");
        ComponentName componentName = intent.resolveActivity(getPackageManager());
        if (componentName != null) {
            startActivityForResult(intent, REQUEST_ALBUM);
        }
    }

然后在onActivityResult()方法中解析相冊的物理路徑:

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode != RESULT_OK) {
            return;
        }
        switch (requestCode) {
            case REQUEST_ALBUM: 
               mImageView.setImageBitmap(BitmapFactory.decodeFile(parsePicturePath(this, data.getData())));
                
                break;
        }
    }

獲取圖片的物理路徑如下:在API19之前和API19之后實現方式不一樣:

    // 解析獲取圖片庫圖片Uri物理路徑
    @SuppressLint("NewApi")
    private String parsePicturePath(Context context, Uri uri) {

        if (null == context || uri == null)
            return null;

        boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;
        // DocumentUri
        if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
            // ExternalStorageDocumentsUri
            if (isExternalStorageDocumentsUri(uri)) {
                String docId = DocumentsContract.getDocumentId(uri);
                String[] splits = docId.split(":");
                String type = splits[0];
                if ("primary".equalsIgnoreCase(type)) {
                    return Environment.getExternalStorageDirectory() + File.separator + splits[1];
                }
            }
            // DownloadsDocumentsUri
            else if (isDownloadsDocumentsUri(uri)) {
                String docId = DocumentsContract.getDocumentId(uri);
                Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"), Long.valueOf(docId));
                return getDataColumn(context, contentUri, null, null);
            }
            // MediaDocumentsUri
            else if (isMediaDocumentsUri(uri)) {
                String docId = DocumentsContract.getDocumentId(uri);
                String[] split = docId.split(":");
                String type = split[0];
                Uri contentUri = null;
                if ("image".equals(type)) {
                    contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
                } else if ("video".equals(type)) {
                    contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
                } else if ("audio".equals(type)) {
                    contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
                }
                String selection = "_id=?";
                String[] selectionArgs = new String[]{split[1]};
                return getDataColumn(context, contentUri, selection, selectionArgs);
            }
        }
        // MediaStore (general)
        else if ("content".equalsIgnoreCase(uri.getScheme())) {
            if (isGooglePhotosContentUri(uri))
                return uri.getLastPathSegment();
            return getDataColumn(context, uri, null, null);
        }
        // File
        else if ("file".equalsIgnoreCase(uri.getScheme())) {
            return uri.getPath();
        }
        return null;

    }

    private String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) {

        Cursor cursor = null;
        String column = "_data";
        String[] projection = {column};
        try {
            cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null);
            if (cursor != null && cursor.moveToFirst()) {
                int index = cursor.getColumnIndexOrThrow(column);
                return cursor.getString(index);
            }
        } finally {
            try {
                if (cursor != null)
                    cursor.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return null;

    }

    private boolean isExternalStorageDocumentsUri(Uri uri) {
        return "com.android.externalstorage.documents".equals(uri.getAuthority());
    }

    private boolean isDownloadsDocumentsUri(Uri uri) {
        return "com.android.providers.downloads.documents".equals(uri.getAuthority());
    }

    private boolean isMediaDocumentsUri(Uri uri) {
        return "com.android.providers.media.documents".equals(uri.getAuthority());
    }

    private boolean isGooglePhotosContentUri(Uri uri) {
        return "com.google.android.apps.photos.content".equals(uri.getAuthority());
    }

圖片裁剪:

在Android7.0之前我們的裁剪方法如下:

    public void cropPicture(File file) {

        String cropImageName = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss", Locale.getDefault()).format(new Date()) +
                "-1-" + System.currentTimeMillis() + ".jpg";
        File cropFile = new File(getExternalCacheDir(), cropImageName);
        //注意到此處使用的file:// uri類型.
        cropUri = Uri.fromFile(cropFile);
        Intent intent = new Intent("com.android.camera.action.CROP");
        intent.setDataAndType(Uri.fromFile(file), "image/*"); //此處有問題
        intent.putExtra("crop", "true");
        intent.putExtra("aspectX", 1);
        intent.putExtra("aspectY", 1);
        intent.putExtra("outputX", 200);
        intent.putExtra("outputY", 200);
        intent.putExtra("return-data", false);
        intent.putExtra(MediaStore.EXTRA_OUTPUT, cropUri);
        intent.putExtra("outputFormat", Bitmap.CompressFormat.JPEG.toString());
        intent.putExtra("noFaceDetection", true);
        ComponentName componentName = intent.resolveActivity(getPackageManager());
        if (componentName != null) {
            startActivityForResult(intent, REQUEST_PICTURE_CROP);
        }

很顯然,intent.setDataAndType()中的uri是有問題的,因為Uri的類型很多(此處主要是content和file類型),那么不能簡單的用Uri.fromfile(file)這個方法得到文件的uri,應該區分何時是File uri,何時是Content uri.修正辦法如下:

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            sourceUri = getImageContentUri(this, file);
    } else {
            sourceUri = Uri.fromFile(file);
    }

    intent.setDataAndType(sourceUri, "image/*"); 
    
    //獲取文件的Content uri路徑 
    public static Uri getImageContentUri(Context context, File imageFile) {
        String filePath = imageFile.getAbsolutePath();
        Cursor cursor = context.getContentResolver().query(
                MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
                new String[]{MediaStore.Images.Media._ID},
                MediaStore.Images.Media.DATA + "=? ",
                new String[]{filePath}, null);

        if (cursor != null && cursor.moveToFirst()) {
            int id = cursor.getInt(cursor
                    .getColumnIndex(MediaStore.MediaColumns._ID));
            Uri baseUri = Uri.parse("content://media/external/images/media");
            return Uri.withAppendedPath(baseUri, "" + id);
        } else {
            if (imageFile.exists()) {
                ContentValues values = new ContentValues();
                values.put(MediaStore.Images.Media.DATA, filePath);
                return context.getContentResolver().insert(
                        MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);
            } else {
                return null;
            }
        }
    }   

最后在onActivityResult()中獲取到裁剪后的圖片的物理地址即可:

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode != RESULT_OK) {
            return;
        }
        switch (requestCode) {
            case REQUEST_PICTURE_CROP:
                if (cropUri != null) {
                    String path = parsePicturePath(this, cropUri);
                //  String imageName = path.substring(path.lastIndexOf("/") + 1); //得到圖片名稱
                    mImageView.setImageBitmap(BitmapFactory.decodeFile(path));
                }

                break;
        }

參考資料

• 拍照相冊及裁剪的終極實現
• Android7.0適配心得
• android7.0+相機拍照FileUriExposedException
• Android7.0適配之圖片裁剪
• file:// scheme is now not allowed to be attached with Intent on targetSdkVersion 24 (Android Nougat). And here is the solution.