Need to handle uncaught exception and send log file

When my app creates an unhandled exception, rather than simply terminating, I'd like to first give the user an opportunity to send a log file. I realize that doing more work after getting a random exception is risky but, hey, the worst is the app finishes crashing and the log file doesn't get sent. This is turning out to be trickier than I expected :)

What works: (1) trapping the uncaught exception, (2) extracting log info and writing to a file.

What doesn't work yet: (3) starting an activity to send email. Ultimately, I'll have yet another activity to ask the user's permission. If I get the email activity working, I don't expect much trouble for the other.

The crux of the problem is that the unhandled exception is caught in my Application class. Since that isn't an Activity, it's not obvious how to start an activity with Intent.ACTION_SEND. That is, normally to start an activity one calls startActivity and resumes with onActivityResult. These methods are supported by Activity but not by Application.

Any suggestions on how to do this?

Here are some code snips as a starting guide:

public class MyApplication extends Application
{
defaultUncaughtHandler = Thread.getDefaultUncaughtExceptionHandler();
public void onCreate ()
{
Thread.setDefaultUncaughtExceptionHandler (new Thread.UncaughtExceptionHandler()
{
@Override
public void uncaughtException (Thread thread, Throwable e)
{
handleUncaughtException (thread, e);
}
});
}


private void handleUncaughtException (Thread thread, Throwable e)
{
String fullFileName = extractLogToFile(); // code not shown


// The following shows what I'd like, though it won't work like this.
Intent intent = new Intent (Intent.ACTION_SEND);
intent.setType ("plain/text");
intent.putExtra (Intent.EXTRA_EMAIL, new String[] {"me@mydomain.example"});
intent.putExtra (Intent.EXTRA_SUBJECT, "log file");
intent.putExtra (Intent.EXTRA_STREAM, Uri.parse ("file://" + fullFileName));
startActivityForResult (intent, ACTIVITY_REQUEST_SEND_LOG);
}


public void onActivityResult (int requestCode, int resultCode, Intent data)
{
if (requestCode == ACTIVITY_REQUEST_SEND_LOG)
System.exit(1);
}
}
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最佳答案

Here's the complete solution (almost: I omitted the UI layout and button handling) - derived from a lot of experimentation and various posts from others related to issues that came up along the way.

There are a number of things you need to do:

  1. Handle uncaughtException in your Application subclass.
  2. After catching an exception, start a new activity to ask the user to send a log.
  3. Extract the log info from logcat's files and write to your own file.
  4. Start an email app, providing your file as an attachment.
  5. Manifest: filter your activity to be recognized by your exception handler.
  6. Optionally, setup Proguard to strip out Log.d() and Log.v().

Now, here are the details:

(1 & 2) Handle uncaughtException, start send log activity:

public class MyApplication extends Application
{
public void onCreate ()
{
// Setup handler for uncaught exceptions.
Thread.setDefaultUncaughtExceptionHandler (new Thread.UncaughtExceptionHandler()
{
@Override
public void uncaughtException (Thread thread, Throwable e)
{
handleUncaughtException (thread, e);
}
});
}


public void handleUncaughtException (Thread thread, Throwable e)
{
e.printStackTrace(); // not all Android versions will print the stack trace automatically


Intent intent = new Intent ();
intent.setAction ("com.mydomain.SEND_LOG"); // see step 5.
intent.setFlags (Intent.FLAG_ACTIVITY_NEW_TASK); // required when starting from Application
startActivity (intent);


System.exit(1); // kill off the crashed app
}
}

(3) Extract log (I put this an my SendLog Activity):

private String extractLogToFile()
{
PackageManager manager = this.getPackageManager();
PackageInfo info = null;
try {
info = manager.getPackageInfo (this.getPackageName(), 0);
} catch (NameNotFoundException e2) {
}
String model = Build.MODEL;
if (!model.startsWith(Build.MANUFACTURER))
model = Build.MANUFACTURER + " " + model;


// Make file name - file must be saved to external storage or it wont be readable by
// the email app.
String path = Environment.getExternalStorageDirectory() + "/" + "MyApp/";
String fullName = path + <some name>;


// Extract to file.
File file = new File (fullName);
InputStreamReader reader = null;
FileWriter writer = null;
try
{
// For Android 4.0 and earlier, you will get all app's log output, so filter it to
// mostly limit it to your app's output.  In later versions, the filtering isn't needed.
String cmd = (Build.VERSION.SDK_INT <= Build.VERSION_CODES.ICE_CREAM_SANDWICH_MR1) ?
"logcat -d -v time MyApp:v dalvikvm:v System.err:v *:s" :
"logcat -d -v time";


// get input stream
Process process = Runtime.getRuntime().exec(cmd);
reader = new InputStreamReader (process.getInputStream());


// write output stream
writer = new FileWriter (file);
writer.write ("Android version: " +  Build.VERSION.SDK_INT + "\n");
writer.write ("Device: " + model + "\n");
writer.write ("App version: " + (info == null ? "(null)" : info.versionCode) + "\n");


char[] buffer = new char[10000];
do
{
int n = reader.read (buffer, 0, buffer.length);
if (n == -1)
break;
writer.write (buffer, 0, n);
} while (true);


reader.close();
writer.close();
}
catch (IOException e)
{
if (writer != null)
try {
writer.close();
} catch (IOException e1) {
}
if (reader != null)
try {
reader.close();
} catch (IOException e1) {
}


// You might want to write a failure message to the log here.
return null;
}


return fullName;
}

(4) Start an email app (also in my SendLog Activity):

private void sendLogFile ()
{
String fullName = extractLogToFile();
if (fullName == null)
return;


Intent intent = new Intent (Intent.ACTION_SEND);
intent.setType ("plain/text");
intent.putExtra (Intent.EXTRA_EMAIL, new String[] {"log@mydomain.example"});
intent.putExtra (Intent.EXTRA_SUBJECT, "MyApp log file");
intent.putExtra (Intent.EXTRA_STREAM, Uri.parse ("file://" + fullName));
intent.putExtra (Intent.EXTRA_TEXT, "Log file attached."); // do this so some email clients don't complain about empty body.
startActivity (intent);
}

(3 & 4) Here's what SendLog looks like (you'll have to add the UI, though):

public class SendLog extends Activity implements OnClickListener
{
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
requestWindowFeature (Window.FEATURE_NO_TITLE); // make a dialog without a titlebar
setFinishOnTouchOutside (false); // prevent users from dismissing the dialog by tapping outside
setContentView (R.layout.send_log);
}


@Override
public void onClick (View v)
{
// respond to button clicks in your UI
}


private void sendLogFile ()
{
// method as shown above
}


private String extractLogToFile()
{
// method as shown above
}
}

(5) Manifest:

<manifest xmlns:android="http://schemas.android.com/apk/res/android" ... >
<!-- needed for Android 4.0.x and eariler -->
<uses-permission android:name="android.permission.READ_LOGS" />


<application ... >
<activity
android:name="com.mydomain.SendLog"
android:theme="@android:style/Theme.Dialog"
android:textAppearance="@android:style/TextAppearance.Large"
android:windowSoftInputMode="stateHidden">
<intent-filter>
<action android:name="com.mydomain.SEND_LOG" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
</application>
</manifest>

(6) Setup Proguard:

In project.properties, change the config line. You must specify "optimize" or Proguard will not remove Log.v() and Log.d() calls.

proguard.config=${sdk.dir}/tools/proguard/proguard-android-optimize.txt:proguard-project.txt

In proguard-project.txt, add the following. This tell Proguard to assume Log.v and Log.d have no side effects (even though they do since they write to the logs) and thus can be removed during optimization:

-assumenosideeffects class android.util.Log {
public static int v(...);
public static int d(...);
}

That's it! If you have any suggestions for improvements to this, please let me know and I may update this.

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Nicely explained. But one observation here, instead of writing into file using File Writer and Streaming, I made use of the logcat -f option directly. Here is the code 

String[] cmd = new String[] {"logcat","-f",filePath,"-v","time","<MyTagName>:D","*:S"};
try {
Runtime.getRuntime().exec(cmd);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

This helped me in flushing the latest buffer info. Using File streaming gave me one issue that it was not flushing the latest logs from buffer. But anyway, this was really helpful guide. Thank you.

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Try using ACRA instead - it handles sending the stack trace as well as tons of other useful debug information to your backend, or to Google Docs document you've set up.

https://github.com/ACRA/acra

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@PeriHartman's answer works well when the UI thread throws uncaught exception. I made some improvements for when the uncaught exception is thrown by a non UI thread.

public boolean isUIThread(){
return Looper.getMainLooper().getThread() == Thread.currentThread();
}


public void handleUncaughtException(Thread thread, Throwable e) {
e.printStackTrace(); // not all Android versions will print the stack trace automatically


if(isUIThread()) {
invokeLogActivity();
}else{  //handle non UI thread throw uncaught exception


new Handler(Looper.getMainLooper()).post(new Runnable() {
@Override
public void run() {
invokeLogActivity();
}
});
}
}


private void invokeLogActivity(){
Intent intent = new Intent ();
intent.setAction ("com.mydomain.SEND_LOG"); // see step 5.
intent.setFlags (Intent.FLAG_ACTIVITY_NEW_TASK); // required when starting from Application
startActivity (intent);


System.exit(1); // kill off the crashed app
}
小开

Today there are many crash reprting tools that do this easily.

  1. crashlytics - A crash reporting tool, free of charge but gives you basic reports Advantages : Free

  2. Gryphonet - A more advanced reporting tool, requires some kind of fee. Advantages : Easy recreation of crashes, ANR's, slowness...

If you are a private developer I would suggest Crashlytics, but if it's a big organization, I would go for Gryphonet.

Good Luck!

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You can handle the uncaught exceptions using FireCrasher library and do a recovery from it.

you can know more about the library in this Medium Article

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Handling uncaught Exceptions: as @gilm explained just do this, (kotlin):

private val defaultUncaughtHandler = Thread.getDefaultUncaughtExceptionHandler();


override fun onCreate() {
//...
Thread.setDefaultUncaughtExceptionHandler { t, e ->
Crashlytics.logException(e)
defaultUncaughtHandler?.uncaughtException(t, e)
}
}

I hope it helps, it worked for me.. (:y). In my case I've used 'com.microsoft.appcenter.crashes.Crashes' library for error tracking.

小开

Here's a solution I devised based on Peri's answer and gilm's comments.

Create the following Kotlin UncaughtExceptionHandler Class:

import android.content.Context
import android.content.Intent
import com.you.website.presentation.activity.MainActivity
import java.io.StringWriter
import android.os.Process
import android.util.Log
import com.google.firebase.crashlytics.FirebaseCrashlytics
import kotlin.system.exitProcess


/**
* When a crash occurs, Android attempts to restart the current and preceding activity by default.
* This is not desired functionality because in most apps there is not enough data persisted to properly recreate recreate the activities.
* This can result in restarting with "Welcome, null" at the top of the page.
* Instead, when a crash occurs, we want the app to crash gracefully and restart from its initial screen.
* This UncaughtExceptionHandler catches uncaught exceptions and returns to the its initial startup Activity.
*/
class UncaughtExceptionHandler(val context: Context, private val defaultUncaughtHandler: Thread.UncaughtExceptionHandler?) : Thread.UncaughtExceptionHandler {
override fun uncaughtException(thread: Thread, exception: Throwable) {
// Begin the main activity so when the app is killed, we return to it instead of the currently active activity.
val intent = Intent(context, MainActivity::class.java)
context.startActivity(intent)
// Return to the normal flow of an uncaught exception
if (defaultUncaughtHandler != null) {
defaultUncaughtHandler.uncaughtException(thread, exception)
} else {
// This scenario should never occur. It can only happen if there was no defaultUncaughtHandler when the handler was set up.
val stackTrace = StringWriter()
System.err.println(stackTrace) // print exception in the 'run' tab.
Log.e("UNCAUGHT_EXCEPTION", "exception", exception) // print exception in 'Logcat' tab.
FirebaseCrashlytics.getInstance().recordException(exception) // Record exception in Firebase Crashlytics
Process.killProcess(Process.myPid())
exitProcess(0)
}
}
}

Add the following to your MainActivity's onCreate() method (First activity to open):

Thread.setDefaultUncaughtExceptionHandler(UncaughtExceptionHandler(this, Thread.getDefaultUncaughtExceptionHandler()))
小开

I modified Peri's answer which was extremely helpful. Instead of using Logcat, the Throwable is sent to SEND_LOG via intent putExtra. Then loop though the stack trace in SEND_LOG. Instead of using email, the string is posted to a web page.

Code excerpts that append to his answer:

Application

public void handleUncaughtException (Thread thread, Throwable e)
{
e.printStackTrace();


// Launch error handler
Intent intent = new Intent ();
intent.setAction ("com.mydomain.SEND_LOG");
intent.setFlags (Intent.FLAG_ACTIVITY_NEW_TASK); from Application
intent.putExtra("com.mydomain.thrownexception",e);
startActivity (intent);


Runtime.getRuntime().exit(1);
}

SEND_LOG

public class SendLog extends AppCompatActivity {
public Throwable thrownexception;


@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);


if (getIntent().hasExtra("com.mydomain.thrownexception")) {
thrownexception = (Throwable) getIntent().getExtras().get("com.mydomain.thrownexception");
}
}


private String getLogString() {
String logToUpload = "";
PackageManager manager = context.getPackageManager();
PackageInfo info = null;
try {
info = manager.getPackageInfo(context.getPackageName(), 0);
} catch (PackageManager.NameNotFoundException e2) {
e2.printStackTrace();
}
String model = Build.MODEL;
if (!model.startsWith(Build.MANUFACTURER))
model = Build.MANUFACTURER + " " + model;


try {
logToUpload = logToUpload + "Android version | " + Build.VERSION.SDK_INT + "\n";
logToUpload = logToUpload + "Device | " + model + "\n";
logToUpload = logToUpload + "App version | " + (info == null ? "(null)" : info.versionCode) + "\n";
logToUpload = logToUpload + "Exception | " + thrownException.toString();
} catch (Exception e) {
e.printStackTrace();
return null;
}
logToUpload = logToUpload + stackTraceToString(thrownException);


return logToUpload;
}


public static String stackTraceToString(Throwable throwable) {
String strStackTrace = "";
strStackTrace = strStackTrace + "\nStack Trace |";
strStackTrace = strStackTrace + throwable.toString();
try {
for (StackTraceElement element : throwable.getStackTrace()) {
strStackTrace = strStackTrace + "\n" + element.toString();
}
//  Suppressed exceptions
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
Throwable[] suppressed = throwable.getSuppressed();
if (suppressed.length > 0) {
strStackTrace = strStackTrace + "\nSuppressed |";
for (Throwable elementThrowable : suppressed) {
strStackTrace = strStackTrace + "\n" + elementThrowable.toString();
for (StackTraceElement element : elementThrowable.getStackTrace()) {
strStackTrace = strStackTrace + "\n" + element.toString();
}
}
}
}
//   Recursively call method to include stack traces of exceptions that caused the throwable
if (throwable.getCause() != null) {
strStackTrace = strStackTrace + "\nCaused By:";
strStackTrace = strStackTrace + stackTraceToString(throwable.getCause());
}
} catch (Exception e) {
e.printStackTrace();
}


return strStackTrace;
}

(I don't have enough points to comment on his answer)


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