摘要：
在应用程序中，通常需要转到相册获取图片。每次，我都会忘记。现在我将做一个记录，以供将来参考。
应用中经常会有去相册获取图片的需求，每次总是会忘，现在这做个记录，以便以后查阅。
从应用去相册获取图片主要有以下几个步骤：
1、设置intent调用系统相册
2、进入相册选取图片，如果相册没有满意的图片，可以使用相机照相获取，最后返回数据到应用
3、应用获取图片后，调用裁剪程序对图片进行裁剪
4、返回裁剪的图片并显示出来
一、设置intent调用系统相册，并进入相册选取图片
/** * 调用相册 */ private void goAlbums() { Intent intent = new Intent(Intent.ACTION_GET_CONTENT); intent.addCategory(Intent.CATEGORY_OPENABLE); intent.setType("image/*"); startActivityForResult(intent, SELECT_PIC); }
通过以上设置进入相册，返回的图片数据交由Activity的onActivityResult方法处理，请求码是SELECT_PIC，请求码为int型，可以随意设置
获取到返回的图片之后，下面便进入裁剪的步骤了
二、调用裁剪程序对图片进行裁剪
/** * 裁剪大图 * @param context * @param uri */ private void clipperBigPic(Context context, Uri uri) { if (null == uri) { return; } Intent intent = new Intent("com.android.camera.action.CROP"); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) { String url = PhotoClipperUtil.getPath(context, uri); intent.setDataAndType(Uri.fromFile(new File(url)), "image/*"); } //发送裁剪命令 intent.putExtra("crop", true); //X方向上的比例 intent.putExtra("aspectX", 1); //Y方向上的比例 intent.putExtra("aspectY", 1); //裁剪区的宽 intent.putExtra("outputX", 124); //裁剪区的高 intent.putExtra("outputY", 124); //是否保留比例 intent.putExtra("scale", true); //返回数据 intent.putExtra("return-data", true); //输出图片格式 intent.putExtra("outputFormat", Bitmap.CompressFormat.PNG.toString()); //裁剪图片保存位置 intent.putExtra(MediaStore.EXTRA_OUTPUT, getTempUri()); startActivityForResult(intent, SELECT_CLIPPER_PIC); }
上面代码中的Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT，是因为KITKAT以上版本中返回的data数据和KITKAT以下版本的data数据可能不同，需要单独处理。
下面的代码便是正常处理，设置裁剪的参数，请求的数据同样交由onActivityResult处理
getTempUri为设置临时图片存储目录，代码如下：
private Uri getTempUri() { return Uri.fromFile(getTempFile()); } /** * 临时图片保存路径 * @return */ private File getTempFile() { File file = new File(Environment.getExternalStorageDirectory(), IMAGE_FILE_NAME); try { file.createNewFile(); } catch (IOException e) { e.printStackTrace(); } return file; }
上面代码中中的IMAGE_FILE_NAME需要自己指定
上面代码中的PhotoClipperUtil类代码如下：
package tmg.gotoalarm; import android.annotation.SuppressLint; import android.content.ContentUris; import android.content.Context; import android.database.Cursor; import android.net.Uri; import android.os.Build; import android.os.Environment; import android.provider.DocumentsContract; import android.provider.MediaStore; public class PhotoClipperUtil { @SuppressLint("NewApi") public static String getPath(final Context context, final Uri uri) { final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT; // DocumentProvider if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) { // ExternalStorageProvider if (isExternalStorageDocument(uri)) { final String docId = DocumentsContract.getDocumentId(uri); final String[] split = docId.split(":"); final String type = split[0]; if ("primary".equalsIgnoreCase(type)) { return Environment.getExternalStorageDirectory() + "/" + split[1]; } } // DownloadsProvider else if (isDownloadsDocument(uri)) { final String id = DocumentsContract.getDocumentId(uri); final Uri contentUri = ContentUris.withAppendedId( Uri.parse("content://downloads/public_downloads"), Long.valueOf(id)); return getDataColumn(context, contentUri, null, null); } // MediaProvider else if (isMediaDocument(uri)) { final String docId = DocumentsContract.getDocumentId(uri); final String[] split = docId.split(":"); final 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; } final String selection = "_id=?"; final String[] selectionArgs = new String[] { split[1] }; return getDataColumn(context, contentUri, selection, selectionArgs); } } // MediaStore (and general) else if ("content".equalsIgnoreCase(uri.getScheme())) { // Return the remote address if (isGooglePhotosUri(uri)) return uri.getLastPathSegment(); return getDataColumn(context, uri, null, null); } // File else if ("file".equalsIgnoreCase(uri.getScheme())) { return uri.getPath(); } return null; } /** * Get the value of the data column for this Uri. This is useful for * MediaStore Uris, and other file-based ContentProviders. * * @param context The context. * @param uri The Uri to query. * @param selection (Optional) Filter used in the query. * @param selectionArgs (Optional) Selection arguments used in the query. * @return The value of the _data column, which is typically a file path. */ public static String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) { Cursor cursor = null; final String column = "_data"; final String[] projection = { column }; try { cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null); if (cursor != null && cursor.moveToFirst()) { final int index = cursor.getColumnIndexOrThrow(column); return cursor.getString(index); } } finally { if (cursor != null) cursor.close(); } return null; } /** * @param uri The Uri to check. * @return Whether the Uri authority is ExternalStorageProvider. */ public static boolean isExternalStorageDocument(Uri uri) { return "com.android.externalstorage.documents".equals(uri.getAuthority()); } /** * @param uri The Uri to check. * @return Whether the Uri authority is DownloadsProvider. */ public static boolean isDownloadsDocument(Uri uri) { return "com.android.providers.downloads.documents".equals(uri.getAuthority()); } /** * @param uri The Uri to check. * @return Whether the Uri authority is MediaProvider. */ public static boolean isMediaDocument(Uri uri) { return "com.android.providers.media.documents".equals(uri.getAuthority()); } /** * @param uri The Uri to check. * @return Whether the Uri authority is Google Photos. */ public static boolean isGooglePhotosUri(Uri uri) { return "com.google.android.apps.photos.content".equals(uri.getAuthority()); } }
总的获取相册图片的流程如下：
mGoAlarmIv.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //调用系统相册，进入相册获取图片 goAlbums(); } });
进入相册后，应用的中转工作交由onActivityResult处理
@Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); if (data == null) { return; } switch (requestCode) { case SELECT_PIC: //获取图片后裁剪图片 clipperBigPic(this, data.getData()); break; case SELECT_CLIPPER_PIC: //获取图片后保存图片到本地，是否需要保存看情况而定 saveBitmap(data); //显示图片 showImage(mGoAlarmIv); break; } }
保存图片的代码如下：
/** * 保存图片 * @param data */ private void saveBitmap(Intent data) { Bundle bundle = data.getExtras(); if (bundle != null) { Bitmap bitmap = bundle.getParcelable("data"); File file = new File(Environment.getExternalStorageDirectory(), IMAGE_FILE_NAME); try { file.createNewFile(); FileOutputStream fileOutputStream = new FileOutputStream(file); bitmap.compress(Bitmap.CompressFormat.PNG, 100, fileOutputStream); fileOutputStream.flush(); fileOutputStream.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }
OK，以上便是第三方应用调用相册获取图片的整个流程。