Android调用系统相册的方法

    /**
     * 打开系统相册
     */
    private void openAlbum() {
        Intent intent = new Intent("android.intent.action.GET_CONTENT");
        intent.setType("image/*");
        startActivityForResult(intent, 1004);
    }

@Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == RESULT_OK) {
            switch (requestCode) {
                case 1004:
                    if (Build.VERSION.SDK_INT >= 19) {//当API大于18之后Android对图片的路径进行了封装
                        handleImageOfKitKat(data);
                    } else {
                        handleImageBeforeKitKat(data);
                    }
                    break;
                default:
                    break;
            }
        }
        super.onActivityResult(requestCode, resultCode, data);
    }

    /**
     * API 大于等于19的时候需要对返回的数据进行解析
     *
     * @param data
     */

    private void handleImageOfKitKat(Intent data) {
        String imageUrl = null;
        Uri uri = data.getData();
        if (DocumentsContract.isDocumentUri(this, uri)) {
            String docId = DocumentsContract.getDocumentId(uri);
            if ("com.android.providers.media.documnets".equals(uri.getAuthority())) {//判断uri是不是media格式
                String id = docId.split(":")[1];//是media格式的话将uri进行二次解析取出id
                String selection = MediaStore.Images.Media._ID + "=" + id;
                imageUrl = getImagePath(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, selection);
            } else if ("com.android.providers.downloads.documents".equals(uri.getAuthority())) {
                Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"), Long.valueOf(docId));
                imageUrl = getImagePath(contentUri, null);
            }
        } else if ("content".equalsIgnoreCase(uri.getScheme())) {
            imageUrl = getImagePath(uri, null);
        } else if ("file".equalsIgnoreCase(uri.getScheme())) {
            imageUrl = uri.getPath();
        }
        displayImage(imageUrl);
    }

    private String getImagePath(Uri externalContentUri, String selection) {
        String path = null;
        Cursor cursor = getContentResolver().query(externalContentUri, null, selection, null, null, null);
        if (cursor == null) {
            return path;
        }
        while (cursor.moveToNext()) {
            path = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));
        }
        cursor.close();
        return path;
    }

    /**
     * API小于19的时候返回的就是图片的Url
     *
     * @param data
     */
    private void handleImageBeforeKitKat(Intent data) {
        Uri imageUrl = data.getData();
        String imagePath = imageUrl.getPath();
        displayImage(imagePath);
    }