在我正在开发的应用中，用户可以在他的个人资料中定义图像。第一次执行应用程序时，会显示一个介绍活动，用户可以选择从galery中选择一张照片或者使用相机拍摄一张新照片。
这很好用。用户设置个人资料图片后，我将其保存在app文件夹中，稍后我可以在应用程序中使用该图片。
我的应用程序基于导航抽屉（支持），因此它由片段组成。其中一个片段用于显示配置文件pic的用户配置文件。在这里，用户有机会再次改变这张照片。这是我遇到麻烦的地方。
要选择一个新的图片，我使用的相同代码用于在介绍活动中获取图片，只是将一些内容调整到片段（放置getActivity（））。但似乎并没有将图像返回到片段而且它正在抛出一个NPE。
这就是在SettingsFragment中从图库中选择图片的方式：
Intent galleryIntent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
galleryIntent.setType("image/*");
startActivityForResult(galleryIntent, PICK_IMAGE_REQUEST_FRAG);
这里也是SettingsFragment中的onActivityResult：
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
switch (requestCode) {
case PICK_IMAGE_REQUEST_FRAG:
if (resultCode == getActivity().RESULT_OK && data != null) {
/*We get the image URI*/
Uri selectedImageUri = data.getData();
Bitmap srcBmp = null;
try {
srcBmp = MediaStore.Images.Media.getBitmap(getActivity().getContentResolver(), selectedImageUri);
} catch (FileNotFoundException e) {
Log.e("GET_IMAGE", e.getMessage(), e);
} catch (IOException e) {
Log.e("GET_IMAGE", e.getMessage(), e);
}
/*Transform the original image to landscape to use it as profile background*/
Bitmap landBmp = null;
if (srcBmp.getWidth() <= srcBmp.getHeight()) {
landBmp = Bitmap.createBitmap(
srcBmp,
0,
srcBmp.getHeight()/2 - srcBmp.getWidth()/2, //srcBmp.getHeight()/4 ?
srcBmp.getWidth(),
srcBmp.getWidth() /2
);
}
/*Scale the bitmap*/
int originalWidth = srcBmp.getWidth();
int originalHeight = srcBmp.getHeight();
int newWidth = 400;
int newHeight = (originalHeight*newWidth)/originalWidth;
Bitmap fullbitmap = Bitmap.createScaledBitmap(landBmp, newWidth, newHeight, true);
/*Save the bitmap in app-folder*/
ContextWrapper cw1 = new ContextWrapper(getActivity().getApplicationContext());
File directory1 = cw1.getDir("profile", Context.MODE_PRIVATE);
if (!directory1.exists()) {
directory1.mkdir();
}
File filepath1 = new File(directory1, "profile_pic.png");
FileOutputStream fos1 = null;
try {
fos1 = new FileOutputStream(filepath1);
fullbitmap.compress(Bitmap.CompressFormat.PNG, 100, fos1);
fos1.close();
} catch (Exception e) {
Log.e("SAVE_FULL_IMAGE", e.getMessage(), e);
}
/*Show background profile pic*/
Drawable drawable = new BitmapDrawable(getResources(), fullbitmap);
header_container.setBackgroundDrawable(drawable);
}
break;
但是如上所述，应用程序崩溃了这就是logcat所说的：
java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=131073, result=-1,
data=Intent { dat=content://media/external/images/media/204 flg=0x1 }}
to activity {com.myproject.executer/com.myproject.executer.MainActivity}:
java.lang.NullPointerException at android.app.ActivityThread.deliverResults(ActivityThread.java:3389)
Caused by: java.lang.NullPointerException at android.graphics.Bitmap.createScaledBitmap(Bitmap.java:590)
at com.myproject.executer.SettingsFragment.onActivityResult(SettingsFragment.java:275)
第275行是Bitmap fullbitmap = Bitmap.createScaledBitmap(landBmp, newWidth, newHeight, true);
所以，我不太了解发生了什么，因为它说的是没有将结果归结为MainActivity的东西，它必须将结果传递给SettingsFragment。
答案 0 :(得分：1)
如果onActivityResult()方法没有完成并返回，系统会将其计为交付失败，这就是错误从该消息开始的原因。
在您的代码中，似乎landBmp为空，因为条件srcBmp.getWidth() <= srcBmp.getHeight()为false，在这种情况下您不会初始化landBmp。这会抛出NullPointerException，并在onActivityResult()返回之前暂停执行。
答案 1 :(得分：0)
创建ActivityResultEvent.java
import android.content.Intent;
/**
* Created by nuuneoi on 3/12/2015.
*/
public class ActivityResultEvent {
private int requestCode;
private int resultCode;
private Intent data;
public ActivityResultEvent(int requestCode, int resultCode, Intent data) {
this.requestCode = requestCode;
this.resultCode = resultCode;
this.data = data;
}
public int getRequestCode() {
return requestCode;
}
public void setRequestCode(int requestCode) {
this.requestCode = requestCode;
}
public int getResultCode() {
return resultCode;
}
public void setResultCode(int resultCode) {
this.resultCode = resultCode;
}
public Intent getData() {
return data;
}
public void setData(Intent data) {
this.data = data;
}
}
创建ActivityResultBus.java
import android.os.Handler;
import android.os.Looper;
import com.squareup.otto.Bus;
/**
* Created by nuuneoi on 3/12/2015.
*/
public class ActivityResultBus extends Bus {
private static ActivityResultBus instance;
public static ActivityResultBus getInstance() {
if (instance == null)
instance = new ActivityResultBus();
return instance;
}
private Handler mHandler = new Handler(Looper.getMainLooper());
public void postQueue(final Object obj) {
mHandler.post(new Runnable() {
@Override
public void run() {
ActivityResultBus.getInstance().post(obj);
}
});
}
}
//＆gt;＆gt;＆gt;＆gt;＆gt;＆gt;＆gt;＆gt;＆gt;＆gt;＆gt;＆gt;＆gt;＆gt;＆gt;＆gt; 覆盖活动上的onActivityResult
public class MainActivity extends ActionBarActivity {
...
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
ActivityResultBus.getInstance().postQueue(
new ActivityResultEvent(requestCode, resultCode, data));
}
...
}
片段：
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
// Don't forget to check requestCode before continuing your job
if (requestCode == 12345) {
// Do your job
tvResult.setText("Result Code = " + resultCode);
}
}
@Override
public void onStart() {
super.onStart();
ActivityResultBus.getInstance().register(mActivityResultSubscriber);
}
@Override
public void onStop() {
super.onStop();
ActivityResultBus.getInstance().unregister(mActivityResultSubscriber);
}
private Object mActivityResultSubscriber = new Object() {
@Subscribe
public void onActivityResultReceived(ActivityResultEvent event) {
int requestCode = event.getRequestCode();
int resultCode = event.getResultCode();
Intent data = event.getData();
onActivityResult(requestCode, resultCode, data);
}
};