Android——从相机/相册获取图片

从相机获取图片

• 设置权限

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

• 点击跳转

    private static final int REQUEST_CODE_TAKE = 1;

    public void takePhoto(View view) {if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) == PackageManager.PERMISSION_GRANTED) {doTake();} else {ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, REQUEST_CODE_TAKE);}}

• 权限结果回调

    @Overridepublic void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {super.onRequestPermissionsResult(requestCode, permissions, grantResults);if (requestCode == REQUEST_CODE_TAKE) {if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {doTake();} else {Toast.makeText(this, "你没有获得摄像头权限", Toast.LENGTH_SHORT).show();}}}

        register = registerForActivityResult(new ActivityResultContracts.StartActivityForResult(), result -> {if (result != null) {if (result.getResultCode() == Activity.RESULT_OK) {try {InputStream inputStream = getContentResolver().openInputStream(imageUri);Bitmap bitmap = BitmapFactory.decodeStream(inputStream);// 转成Base64字符串 方便上传到服务器imageBase64 = ImageUtil.imageToBase64(bitmap);ivAvatar.setImageBitmap(bitmap);} catch (FileNotFoundException e) {e.printStackTrace();}}}});

• 在 onCreate 中注册 Activity 返回结果回调

    private void doTake() {File imageTemp = new File(getExternalCacheDir(), "imageOut.jpeg");if (imageTemp.exists()) {imageTemp.delete();}try {imageTemp.createNewFile();} catch (IOException e) {e.printStackTrace();}imageUri = Uri.fromFile(imageTemp);if (Build.VERSION.SDK_INT > 24) {imageUri = FileProvider.getUriForFile(this, "com.example.study_android.fileprovider", imageTemp);}Intent intent = new Intent();intent.setAction("android.media.action.IMAGE_CAPTURE");intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);register.launch(intent);}

• 设置provider

        <providerandroid:authorities="com.example.study_android.fileprovider"android:name="androidx.core.content.FileProvider"android:exported="false"android:grantUriPermissions="true"><meta-data android:name="android.support.FILE_PROVIDER_PATHS"android:resource="@xml/files"/></provider>

• @xml/files

	<paths xmlns:android="http://schemas.android.com/apk/res/android"><external-pathname="image_path"path="/"/></paths>

从相册获取图片

• 设置权限

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

• 打开相册（需判断权限）

    public void choosePhoto(View view) {// 权限WRITE_EXTERNAL_STORAGE表示同时授予程序对SD卡读和写的能力。if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {openAlbum();} else {ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_CODE_CHOOSE);}}private void openAlbum() {Intent intent = new Intent("android.intent.action.GET_CONTENT");intent.setType("image/*");registerAlbum.launch(intent);}

• 注册相册返回结果回调

        registerAlbum = registerForActivityResult(new ActivityResultContracts.StartActivityForResult(), result -> {if (result != null) {if (result.getResultCode() == Activity.RESULT_OK) {Intent intent = result.getData();if (Build.VERSION.SDK_INT < 19) {handleImageBeforeApi19(intent);} else {handleImageOnApi19(intent);}}}});

    private void handleImageBeforeApi19(Intent data) {Uri uri = data.getData();String imagePath = getImagePath(uri, null);displayImage(imagePath);}

    /** 因为Android系统从4.4版本开始，选取相册中的图片不再返回图片真实的Uri了，而是一个封装过的Uri* 因此如果是4.4版本以上的手机就需要对这个Uri进行解析才行* */@TargetApi(19)private void handleImageOnApi19(Intent data) {String imagePath = null;Uri uri = data.getData();if (DocumentsContract.isDocumentUri(this, uri)) {// 如果是document类型的Uri，则通过document id处理String documentId = DocumentsContract.getDocumentId(uri);if (TextUtils.equals(uri.getAuthority(), "com.android.providers.media.documents")) {String id = documentId.split(":")[1];String selection = MediaStore.Images.Media._ID + "=" + id;imagePath = getImagePath(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, selection);} else if (TextUtils.equals(uri.getAuthority(), "com.android.providers.downloads.documents")) {if (documentId != null && documentId.startsWith("msf:")) {resolveMSFContent(uri);return;}Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"), Long.valueOf(documentId));imagePath = getImagePath(contentUri, null);}} else if ("content".equalsIgnoreCase(uri.getScheme())) {// 如果是content类型的Uri，则使用普通方式处理imagePath = getImagePath(uri, null);} else if ("file".equalsIgnoreCase(uri.getScheme())) {// 如果是file类型的Uri，直接获取图片路径imagePath = uri.getPath();}displayImage(imagePath);}

    private void resolveMSFContent(Uri uri) {File file = new File(getCacheDir(), "temp_file" + getContentResolver().getType(uri).split("/")[1]);try {InputStream inputStream = getContentResolver().openInputStream(uri);OutputStream outputStream = new FileOutputStream(file);byte[] buffer = new byte[4 * 1024];int read;while ((read = inputStream.read(buffer)) != -1) {outputStream.write(buffer, 0, read);}outputStream.flush();Bitmap bitmap = BitmapFactory.decodeFile(file.getAbsolutePath());ivAvatar.setImageBitmap(bitmap);} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}

    // 获取图片真实路径@SuppressLint("Range")private String getImagePath(Uri uri, String selection) {String path = null;// 通过Uri和selection来获取真实的图片路径Cursor cursor = getContentResolver().query(uri, null, selection, null, null);if (cursor != null) {if (cursor.moveToFirst()) {path = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));}cursor.close();}return path;}

案例代码