Android：如何将图像加载到位图中答案

【问题标题】：Android: How to load image into BitmapAndroid：如何将图像加载到位图中
【发布时间】：2011-02-03 14:22:53
【问题描述】：

我可以从可绘制文件夹中将资源图像加载到位图中，甚至可以很好地缩放，但是现在我需要从 SD 卡上存储的任何图像中加载图像，我可以看到这将允许我查看和选择；

    startActivityForResult(new Intent(Intent.ACTION_PICK,
         android.provider.MediaStore.Images.Media.INTERNAL_CONTENT_URI), 1);

但是到目前为止，我一直无法准确地找出返回的数据以及如何将其加载到位图中。

更新：

这就是我现在得到的；

@Override
protected void onActivityResult(int requestCode, int resultCode,
            Intent intent) {
  super.onActivityResult(requestCode, resultCode, intent);

if (resultCode == RESULT_OK) {

    Uri contentURI =  Uri.parse(intent.getDataString());

    c = mSurfaceHolder.lockCanvas();

    tempCanvas.setBitmap(mDrawing);

    Bitmap tempBitmap = null;

    ContentResolver cr = getContentResolver();

    try {           
      InputStream in = cr.openInputStream(contentURI);
      BitmapFactory.Options options = new BitmapFactory.Options();
      options.inSampleSize=8;
      tempBitmap = BitmapFactory.decodeStream(in,null,options);
        }
    catch (Exception ee) {
      tempBitmap = BitmapFactory.decodeResource(getResources(),
                    R.drawable.icon);
        }

    tempCanvas.drawBitmap(tempBitmap, 0, 0, null);
    c.drawBitmap(tempBitmap, 0, 0, null);

    mSurfaceHolder.unlockCanvasAndPost(c);
  }
}

在显示 logcat 时出现“应用程序意外停止”错误；

ERROR/AndroidRuntime(24768): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { act=com.htc.HTCAlbum.action.ITEM_PICKER_FROM_COLLECTIONS dat=content://media/external/images/media/185 }} to activity {com.example.colorbook/com.example.colorbook.Colorbook}: java.lang.NullPointerException


Complete logcat as it finished gallery view activity and tried to return intent;<br>
02-03 10:47:22.042: DEBUG/MainActivity(22984): [HTCAlbum][MainActivity][onPause]: Begin<br>02-03 10:47:22.042: DEBUG/MainActivity(22984): store mCurrentPosition_backup=0<br>02-03 10:47:22.042: DEBUG/DisplayManager(22984): store mCurrentPosition_backup=0<br>02-03 10:47:22.092: DEBUG/dalvikvm(22984): GC_EXPLICIT freed 1459 objects / 91880 bytes in 44ms<br>02-03 10:47:22.102: INFO/AlbumMapper(22984): Create thumbnail for: /mnt/sdcard/workspace/Colorbook/res/drawable/fileload.png<br>02-03 10:47:22.102: DEBUG/ThumbnailWorker(22984): [stopWorking] Stop working, now join #37, /mnt/sdcard/workspace/Colorbook/res/drawable/fileload.png<br>02-03 10:47:22.102: DEBUG/AlbumAdapter(22984): set thread priority to normal<br>02-03 10:47:22.102: DEBUG/AbstractViewGetter(22984): Raise getter prefetcher thread priority to normal.<br>02-03 10:47:22.102: DEBUG/AbstractViewGetter(22984): Join getter prefetch thread<br>02-03 10:47:22.102: DEBUG/AbstractViewGetter(22984): Getter prefetch join time: 2<br>02-03 10:47:22.102: DEBUG/AlbumMapper(22984): cancel current decode operation<br>02-03 10:47:22.182: DEBUG/AndroidRuntime(24768): Shutting down VM<br>02-03 10:47:22.182: WARN/dalvikvm(24768): threadid=1: thread exiting with uncaught exception (group=0x400259f8)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768): FATAL EXCEPTION: main<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { act=com.htc.HTCAlbum.action.ITEM_PICKER_FROM_COLLECTIONS dat=content://media/external/images/media/185 }} to activity {com.example.colorbook/com.example.colorbook.Colorbook}: java.lang.NullPointerException<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at android.app.ActivityThread.deliverResults(ActivityThread.java:3734)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at android.app.ActivityThread.handleSendResult(ActivityThread.java:3776)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at android.app.ActivityThread.access$2800(ActivityThread.java:135)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2166)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at android.os.Handler.dispatchMessage(Handler.java:99)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at android.os.Looper.loop(Looper.java:144)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at android.app.ActivityThread.main(ActivityThread.java:4937)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at java.lang.reflect.Method.invokeNative(Native Method)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at java.lang.reflect.Method.invoke(Method.java:521)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at dalvik.system.NativeStart.main(Native Method)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768): Caused by: java.lang.NullPointerException<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at com.example.colorbook.Colorbook.loadImageToCanvas(Colorbook.java:524)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at com.example.colorbook.Colorbook.onActivityResult(Colorbook.java:231)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at android.app.Activity.dispatchActivityResult(Activity.java:3931)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     at android.app.ActivityThread.deliverResults(ActivityThread.java:3730)<br>02-03 10:47:22.182: ERROR/AndroidRuntime(24768):     ... 11 more<br>02-03 10:47:22.202: WARN/ActivityManager(97):   Force finishing activity com.example.colorbook/.Colorbook<br>02-03 10:47:22.704: WARN/ActivityManager(97): Activity pause timeout for HistoryRecord{46207010 com.example.colorbook/.Colorbook}<br>02-03 10:47:22.742: DEBUG/Sensors(97): close_akm, fd=114<br>02-03 10:47:22.852: DEBUG/MainActivity(22984): [HTCAlbum][MainActivity][onStop]: Begin<br>02-03 10:47:22.902: DEBUG/dalvikvm(22984): GC_EXPLICIT freed 398 objects / 23264 bytes in 38ms<br>02-03 10:47:22.902: DEBUG/MainActivity(22984): [HTCAlbum][MainActivity][onDestroy]: Begin<br>02-03 10:47:22.912: DEBUG/OnlineDataCenter(22984): [HTCAlbum][OnlineDataCenter][unbindContext]: Begin<br>02-03 10:47:22.912: DEBUG/OnlineDataCenter(22984): [HTCAlbum][OnlineDataCenter][unbindContext]: com.htc.album.MainActivity@46075ec0context size: 0<br>02-03 10:47:22.912: DEBUG/OnlineDataCenter(22984): [HTCAlbum][OnlineDataCenter][unbindContext]: No more clients. release resources.<br>02-03 10:47:22.912: DEBUG/OnlineDataCenter(22984): [HTCAlbum][OnlineDataCenter][unbindContext]: End 0<br>02-03 10:47:22.912: DEBUG/ThumbnailWorker(22984): [stopWorking] Stop working, now join #-1, Decode Complete!!<br>02-03 10:47:22.912: DEBUG/AlbumAdapter(22984): set thread priority to normal<br>02-03 10:47:22.912: DEBUG/AlbumMapper(22984): cancel current decode operation<br>02-03 10:47:22.912: DEBUG/AlbumMapper(22984): cancel current decode operation<br>02-03 10:47:22.912: DEBUG/ThumbnailWorker(22984): [stopWorking] Stop working, now join #-1, Decode Complete!!<br>02-03 10:47:22.912: DEBUG/AlbumAdapter(22984): set thread priority to normal<br>02-03 10:47:22.912: DEBUG/AlbumAdapter(22984): Join worker thread in destroy<br>02-03 10:47:22.912: DEBUG/AlbumAdapter(22984): Join time: 0<br>02-03 10:47:22.922: INFO/MainActivity(22984): mWorker finishes jobs at onDestroy().<br>02-03 10:47:22.932: DEBUG/CollectionsActivity(22984): [HTCAlbum][CollectionsActivity][onDestroy]: Begin<br>02-03 10:47:22.932: DEBUG/AlbColAdap(22984): [HTCAlbum][AlbumCollectionsAdapter][onDestroy]: Begin<br>02-03 10:47:22.942: INFO/BatteryStatsImpl(97): notePhoneSignalStrengthLocked: 2->3<br>02-03 10:47:22.952: DEBUG/AlbColAdap(22984): [HTCAlbum][AlbumCollectionsAdapter][onDestroy]: End<br>

【问题讨论】：

标签： android image load bitmap sd-card

【解决方案1】：

我使用这个意图：

myIntent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);

然后用它来获取图像

protected void onActivityResult(int requestCode, int resultCode, Intent imageReturnedIntent) { 
    super.onActivityResult(requestCode, resultCode, imageReturnedIntent);
    switch(requestCode){
    case IMAGE_UPLOAD: //this is a constant, in your case I think it should be '1'
        if(imageReturnedIntent != null){// e.g. "back" pressed"
            Uri contentURI = Uri.parse(imageReturnedIntent.getDataString());        
            ContentResolver cr = getContentResolver();
            InputStream in = cr.openInputStream(contentURI);
            BitmapFactory.Options options = new BitmapFactory.Options();
            options.inSampleSize=8;
            Bitmap thumb = BitmapFactory.decodeStream(in,null,options);
       }
    break;

}

我正在发送该字符串，但最终会发生这种情况：

你有，在这种情况下，图像的拇指。如果您想要更大，请使用不同的样本大小:)

【讨论】：

好的，非常感谢您的快速回复，但是如果这似乎是一个无知的问题，请保持我对 Java 和 Android 都相当陌生，但是 cr 是什么？ InputStream in = cr.openInputStream(contentURI);
我用过这个，也是因为我需要流，但它的作用是从“uri”创建一个流（就像你可能使用 web-URI 一样），然后创建来自该流的位图。阅读此内容以了解流中的基本介绍：download.oracle.com/javase/tutorial/essential/io/streams.html
谢谢我的意思是“cr”，我认为需要像这样编码； ContentResolver cr = this.getContentResolver();
噢，我的错！这只是我从代码中删除各种不必要的东西的产物。我会澄清
我想你可能想为此打开一个单独的问题:)

【解决方案2】：

返回的数据是所选图像的 Uri，您仍然需要加载图像。在您的 onActivityResult 中：

public void onActivityResult(int reqCode, int resultCode, Intent data) {
     ...some code to make sure the result is valid
     Uri imageUri = data.getData();
     imageView.setImageUri(imageUri);
}

您还必须使用 EXTERNAL_CONTENT_URI 与 INTERNAL_CONTENT_URI。这也会在您可能不想做的 UI 线程上加载图像。您需要将其传递给后台线程。

【讨论】：

【解决方案3】：

试试这个：

private String getPath(Uri uri) {
String[]  data = { MediaStore.Images.Media.DATA };
CursorLoader loader = new CursorLoader(context, uri, data, null, null, null);
Cursor cursor = loader.loadInBackground();
int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToFirst();
return cursor.getString(column_index);
}

【讨论】：