Android打开系统相机、相册，并进行裁剪图片的工具类CameraUtil，以及相册获取图片注意要点。

Android中打开手机系统相机和相册，并进行图片裁剪经常被用到，这里写了一个工具类，希望对大家有帮助。主要功能有，获取打开系统相机、相册、裁剪功能的intent，更新手机媒体库方法，以及保存文件功能。详细代码如下：

public class CameraUtil {
    /**
     * 检测SD卡是否可用
     *
     * @return true 可用，false不可用。
     */
    public static boolean isSDExit() {
        return Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);
    }

    /**
     * 新建文件夹到手机本地
     *
     * @param fileFolder ,文件夹的路径名称
     * @return
     */
    public static boolean createDir(String fileFolder) {
        File dir = new File(fileFolder);
        if (!dir.exists()) {
            return dir.mkdirs();
        }
        return false;
    }

    /**
     * 新建文件到手机本地
     *
     * @param fileNameWithPath ,文件名包含路径
     * @return , true新建成功, false新建失败
     */
    public static boolean createFile(String fileNameWithPath) {
        File file = new File(fileNameWithPath);
        try {
            if (isSDExit() && file.exists()) {
                if (file.delete()) {
                    return file.createNewFile();
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

    /**
     * 新建文件到手机指定路径
     *
     * @param dirPath  ,文件的文件夹目录路径
     * @param fileName ,文件名
     * @return , true新建成功, false新建失败
     */
    public static boolean createFile(String dirPath, String fileName) {
        File file = new File(dirPath, fileName);
        try {
            if (isSDExit() && file.exists()) {
                if (file.delete()) {
                    return file.createNewFile();
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }


    /**
     * 创建相机拍照图片名称
     *
     * @param fileType ,文件的类型，即扩展名，例如.jpg 、.mp4 、.mp3等
     * @return , 图片文件名,格式形式20161011_111523.jpg
     */
    public static String createFileName(String fileType) {
        String fileName = "";
        Date date = new Date(System.currentTimeMillis());
        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd_HHmmss");
        fileName = sdf.format(date) + fileType;
        return fileName;
    }

    /**
     * 保存图片的Bitmap数据到sd卡指定路径
     *
     * @param fileNameWithPath ,图片的路径
     * @param bitmap           ,图片的bitmap数据
     */
    public static void savePhotoToPath(String fileNameWithPath, Bitmap bitmap) {
        if (isSDExit()) {
            File file = new File(fileNameWithPath);
            FileOutputStream fos = null;
            try {
                fos = new FileOutputStream(file);
                if (bitmap != null) {
                    if (bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos)) {
                        fos.flush();
                        fos.close();
                    }
                }
            } catch (FileNotFoundException e) {
                file.delete();
                e.printStackTrace();
            } catch (IOException e) {
                file.delete();
                e.printStackTrace();
            } finally {
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    /**
     * 删除文件
     *
     * @param dirPath  ,文件的文件夹目录路径
     * @param fileName ,文件名
     * @return , true删除成功, false删除失败
     */
    public static boolean deleteFile(String dirPath, String fileName) {
        File file = new File(dirPath, fileName);
        if (!file.exists()) {
            return true;
        }
        return file.delete();
    }

    /**
     * 更新系统的Media库
     *
     * @param context
     */
    public static void updateSystemMedia(Context context) {
        MediaScannerConnection.scanFile(context, new String[]{
                android.os.Environment.getExternalStorageDirectory().getAbsolutePath()
        }, null, null);
    }

    /**
     * 打开手机系统相册, method one
     *
     * @return intent, Activity调用的intent
     */
    public static Intent openAlbum() {
        Intent intent = new Intent("android.intent.action.GET_CONTENT");
        intent.setType("image/*");
        return intent;
    }

    /**
     * 打开手机系统相册, method two
     *
     * @return intent, Activity调用的intent
     */
    public static Intent openGallery() {
        return new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
    }

    /**
     * 打开手机系统相机拍照
     *
     * @param uri , 用于保存手机拍照后所获图片的uri
     * @return intent, Activity调用的intent
     */
    public static Intent openCamera(Uri uri) {
        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        intent.putExtra(MediaStore.EXTRA_OUTPUT, uri);
        intent.putExtra("autofocus", true);//进行自动对焦操作
        return intent;
    }

    /**
     * 打开手机系统的图片裁剪Activity
     *
     * @param inUri  , 待裁剪图片的uri
     * @param outUri , 裁剪后图片保存的uri
     * @return intent , Activity调用的intent
     */
    public static Intent cropPicture(Uri inUri, Uri outUri) {
        Intent intent = new Intent("com.android.camera.action.CROP");
        intent.setDataAndType(inUri, "image/*");     //设置图片资源路径
        intent.putExtra("scale", true);
        intent.putExtra("crop", true);
        intent.putExtra("aspectX", 1);
        intent.putExtra("aspectY", 1);
        intent.putExtra(MediaStore.EXTRA_OUTPUT, outUri);
        return intent;
    }

}

在Activity中调用，请看完整代码：

public class CameraActivity extends AppCompatActivity {

    private final String TAG = getClass().getSimpleName();
    private final int ACT_GALLERY = 0;
    private final int ACT_CAMERA = 1;
    private final int ACT_CROP = 2;
    private final int ACT_PERMISSION = 3;
    private Context context = null;
    private Uri pictureUri = null;
    private String filePath = android.os.Environment.getExternalStorageDirectory() + File.separator + "DICM" + File.separator;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        context = this;
        setContentView(R.layout.activity_camera);
        CameraUtil.createDir(filePath);
        initView();
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode != RESULT_OK) {
            return;
        }
        switch (requestCode) {
            case ACT_GALLERY:
                galleryBack(data.getData());
                break;
            case ACT_CAMERA:
                startCrop(pictureUri);
                break;
            case ACT_CROP:
                cropBack(pictureUri);
                break;
            default:
                break;
        }
        super.onActivityResult(requestCode, resultCode, data);
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permission, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permission, grantResults);
        switch (requestCode) {
            case ACT_PERMISSION:
                if (grantResults.length > 0 && PackageManager.PERMISSION_GRANTED == grantResults[0]) {
                    Log.d(TAG, "permission allowed");
                    Intent intent = CameraUtil.openCamera(pictureUri);
                    startActivityForResult(intent, ACT_CAMERA);
                } else {
                    Log.d(TAG, "permission denied");
                }
                break;
        }
    }

    private void initView() {
        Button openGallery = (Button) findViewById(R.id.btn_gallery);
        Button openCamera = (Button) findViewById(R.id.btn_camera);

        if (openGallery != null) {
            openGallery.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    startGallery();
                }
            });
        }

        if (openCamera != null) {
            openCamera.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    startCamera();
                }
            });
        }

    }

    private void startGallery() {
        Intent intent = CameraUtil.openGallery();
        startActivityForResult(intent, ACT_GALLERY);
    }

    private void startCamera() {
        String fileName = CameraUtil.createFileName(".jpg");
        CameraUtil.createFile(filePath, fileName);
        File file = new File(filePath, fileName);
        pictureUri = Uri.fromFile(file);

        //request the camera permission dynamic above android 6.0
        boolean permission = PackageManager.PERMISSION_GRANTED == ContextCompat.checkSelfPermission(this, android.Manifest.permission.CAMERA);
        if (permission) {
            Intent intent = CameraUtil.openCamera(pictureUri);
            startActivityForResult(intent, ACT_CAMERA);
        }
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            requestPermissions(new String[]{Manifest.permission.CAMERA}, ACT_PERMISSION);
        }

    }

    private void startCrop(Uri inUri) {
        Intent intent = CameraUtil.cropPicture(inUri, pictureUri);
        startActivityForResult(intent, ACT_CROP);
    }

    private void galleryBack(Uri inUri) {
        //get picture uri from gallery
        String[] projection = {MediaStore.Images.Media.DATA};
        Cursor cursor = getContentResolver().query(inUri, projection, null, null, null);
        if (cursor != null) {
            if (cursor.moveToFirst()) {
                String filePath = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));
                startCrop(Uri.fromFile(new File(filePath)));
            }
            if (!cursor.isClosed()) {
                cursor.close();
            }
        }
    }

    private void cropBack(Uri inUri) {
        if (inUri == null) {
            return;
        }
        try {
            Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(inUri));
            //to display or save the picture

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

其中，从相册返回的URI是手机系统媒体库中的URI，一般是以content:///开头，不是我们所希望的直接从文件获取的URI（文件的URI一般是file:///开头），所以需要根据content的uri获取的实际的文件路径，即程序中的：

String[] projection = {MediaStore.Images.Media.DATA};
Cursor cursor = getContentResolver().query(inUri, projection, null, null, null);
if (cursor != null) {
    if (cursor.moveToFirst()) {
        String filePath = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));
        startCrop(Uri.fromFile(new File(filePath)));
    }
    if (!cursor.isClosed()) {
        cursor.close();
    }
}

这点是需要注意的，不然有些手机上是会报获取图片失败。