呵呵，今天很高興，因爲自己正式步入準爸爸階段了！特此記錄下！
好吧，今天，我接着上次的問題講解，如何從android4.4以上系統進行選圖而避免報錯，而
android4.4.4 獲取系統相冊圖片出錯的問題（一）
中介紹的那種方式，其實在性能方面的話，還是一般，因爲每次讀取一張圖片，它都要在本地生成一張，造成存儲空間的浪費。今天介紹的這種方法，是根據網上的不同的資料進行的整理。
第一步：也就是我們調轉到我們的系統相冊進行圖片的選擇
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);// ACTION_OPEN_DOCUMENT
intent.addCategory(Intent.CATEGORY_OPENABLE);
intent.setType("image/jpeg");
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.KITKAT) {/**4.4系統以上**/
startActivityForResult(intent, SELECT_PIC_KITKAT);
} else {
startActivityForResult(intent, SELECT_PIC);
}第二步自然就是在onActivityResult中進行處理
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
switch (requestCode) {
case SELECT_PIC_KITKAT:
if (resultCode != Activity.RESULT_OK) {
return;
}
String path = "";
if (DocumentsContract.isDocumentUri(MainActivity.this,
data.getData())) {
// path = selectImage(MainActivity.this, data);
path = getPath(data);
} else {
path = getPath(MainActivity.this, data);
}
Message msg = new Message();
msg.obj = path;
handler.sendMessage(msg);
break;
case SELECT_PIC:
if (resultCode != Activity.RESULT_OK) {
return;
}
Message msg1 = new Message();
msg1.obj = getPath(data);
handler.sendMessage(msg1);
break;
}
}好，關鍵代碼來了，如下：
public static String getPath(final Context context, Intent data) {
Uri uri = data.getData();
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];
}
// TODO handle non-primary volumes
}
// 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());
}
現在就是通過handler進行本地的顯示：
private Handler handler = new Handler(Looper.getMainLooper()) {
public void handleMessage(android.os.Message msg) {
String path = (String) msg.obj;
// Bitmap myBitmap = getLoacalBitmap(path);
Bitmap bitmap = LocalImageCompression.comp(path);
img.setImageBitmap(bitmap);
};
};其中用到了一個通過本地路徑進行圖片的處理，主要是相冊圖片的size太大了，顯示不了，
/**
* @方法說明:圖片按比例大小壓縮方法（根據路徑獲取圖片並壓縮）
* @方法名稱:getimage
* @param srcPath
* @return
* @返回值:Bitmap
*/
public static Bitmap comp(String srcPath) {
BitmapFactory.Options newOpts = new BitmapFactory.Options();
/** 開始讀入圖片，此時把options.inJustDecodeBounds 設回true了**/
newOpts.inJustDecodeBounds = true;
Bitmap bitmap = BitmapFactory.decodeFile(srcPath, newOpts);/** 此時返回bm爲空**/
newOpts.inJustDecodeBounds = false;
int w = newOpts.outWidth;
int h = newOpts.outHeight;
/** 現在主流手機比較多是800*480分辨率，所以高和寬我們設置爲**/
float hh = 800f;/** 這裏設置高度爲800f**/
float ww = 480f;/** 這裏設置寬度爲480f**/
/** 縮放比。由於是固定比例縮放，只用高或者寬其中一個數據進行計算即可**/
int be = 1;/** be=1表示不縮放**/
if (w > h && w > ww) {/** 如果寬度大的話根據寬度固定大小縮放**/
be = (int) (newOpts.outWidth / ww);
} else if (w < h && h > hh) {/** 如果高度高的話根據寬度固定大小縮放**/
be = (int) (newOpts.outHeight / hh);
}
if (be <= 0)
be = 1;
newOpts.inSampleSize = be;/** 設置縮放比例**/
/** 重新讀入圖片，注意此時已經把options.inJustDecodeBounds 設回false了**/
bitmap = BitmapFactory.decodeFile(srcPath, newOpts);
return compressImage(bitmap);/** 壓縮好比例大小後再進行質量壓縮**/
}源碼地址：http://yunpan.cn/cJ8WZm9NsnvuX （提取碼：3719）
