android 上的编程屏幕截图：setDrawingCacheEnabled 抛出 CalledFromWrongThreadException
在我的一个 robotsium 测试中尝试调用 content.setDrawingCacheEnabled(true) 时，我遇到了问题。当我尝试在上下文中启用绘图缓存时，我有时会收到 CalledFromWrongThreadException。这似乎只发生在模拟器上运行时。当我在设备（三星 S2）上尝试此操作时，它每次都有效...
这是代码
调用函数：
String screnshotName = String.format("SS_Cities_%s.png", s);
File ssDir = Environment.getExternalStorageDirectory();
TestUtilities.takeScreenShot(solo.getCurrentActivity(), ssDir, screnshotName);
屏幕截图函数（抛出异常)：
public static void takeScreenShot(Activity activity, File Directory, String FileName) throws Exception {
View content = activity.findViewById(R.id.content);
***// This is a horrible hack that i want to get rid of***
// Occasiaonally setDrawingCacheEnabled throws a CalledFromWrongThreadException
int MAX_RETRIES = 10;
for(int i = 0; i < MAX_RETRIES; i++)
{
try{
content.setDrawingCacheEnabled(true);
continue;
}
catch (Exception e){}
}
content.buildDrawingCache();
Bitmap b = content.getDrawingCache();
File outputFile = new File(Directory.toString() + "/" + FileName);
try {
if (!Directory.exists()) {
Directory.mkdirs();
}
if (!Directory.canWrite()) {
throw new Exception("Directory not writable");
}
FileOutputStream fos = new FileOutputStream(outputFile);
if (fos != null) {
b.compress(Bitmap.CompressFormat.PNG, 90, fos);
fos.close();
}
} catch (Exception e) {
String screenshotError = String.format("Error taking screenshot: %s", e.toString());
throw new Exception(screenshotError);
}
}
我正在测试的应用程序中设置的权限：
<uses-permission android:name="android.permission.CHANGE_CONFIGURATION"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
I'm running into an issue when trying to call content.setDrawingCacheEnabled(true) in one of my robotium tests. When i try to enable the drawing cache on the context I sometimes get a CalledFromWrongThreadException. This only seems to happen when running on an emulator. When I try this on device (Samsung S2) it works every time...
Here is the code
Calling function:
String screnshotName = String.format("SS_Cities_%s.png", s);
File ssDir = Environment.getExternalStorageDirectory();
TestUtilities.takeScreenShot(solo.getCurrentActivity(), ssDir, screnshotName);
Screenshot function (that throws exception):
public static void takeScreenShot(Activity activity, File Directory, String FileName) throws Exception {
View content = activity.findViewById(R.id.content);
***// This is a horrible hack that i want to get rid of***
// Occasiaonally setDrawingCacheEnabled throws a CalledFromWrongThreadException
int MAX_RETRIES = 10;
for(int i = 0; i < MAX_RETRIES; i++)
{
try{
content.setDrawingCacheEnabled(true);
continue;
}
catch (Exception e){}
}
content.buildDrawingCache();
Bitmap b = content.getDrawingCache();
File outputFile = new File(Directory.toString() + "/" + FileName);
try {
if (!Directory.exists()) {
Directory.mkdirs();
}
if (!Directory.canWrite()) {
throw new Exception("Directory not writable");
}
FileOutputStream fos = new FileOutputStream(outputFile);
if (fos != null) {
b.compress(Bitmap.CompressFormat.PNG, 90, fos);
fos.close();
}
} catch (Exception e) {
String screenshotError = String.format("Error taking screenshot: %s", e.toString());
throw new Exception(screenshotError);
}
}
Permissions set in the application I'm testing:
<uses-permission android:name="android.permission.CHANGE_CONFIGURATION"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
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评论（2）
Android 模拟器在使用外部存储时并不总是能正常工作。这就是您可能会收到这些错误的原因。因此，我建议每当您想要测试使用外部存储的应用程序时，都在真实设备中进行，因为您不会遇到模拟器仍然存在的所有“未修复”错误。
Android emulator doesn't always work fine with external storage. That's why you might get those errors. So I suggest that whenever you want to test apps that use external storage you do it in a real device since you won't have all the "unfixed" errors that the emulator still has.
我看不到您是否从 UIThread 执行 takeScreenShot 方法，但据我所知，我认为您的问题在这里得到了解答：
StackOverflow：CalledFromWrongThreadException
I can't see whether you perform your takeScreenShot method from the UIThread or not but as far as I can see I think your question is being answered here:
StackOverflow: CalledFromWrongThreadException