Question

As a long time log4j user, it is really enjoying to find log4j is available on Android with the help of this project https://code.google.com/p/android-logging-log4j/

For my current Android projects, I am writing logs both to logcat and a file on SD-Card, and the logging file is of great value to my project.

But some recent feedbacks from my beta testing users revealed that if the the SD-Card is removed while my application is writing logs, it will cause a Force-Close.

My current solution is to detect if external storage is mounted when log4j is first used; if no external storage is detected, I will disable log file output.

import java.io.File;

import org.apache.log4j.Level;

import android.os.Environment;
import de.mindpipe.android.logging.log4j.LogConfigurator;

public class ConfigureLog4j {
    private static boolean configured = false;

    public static void configure() {
        if (configured == true) {
            return;
        }

        String status = Environment.getExternalStorageState();

        final LogConfigurator logConfigurator = new LogConfigurator();

        if (status.equals(Environment.MEDIA_MOUNTED)) {
            logConfigurator.setUseFileAppender(true);
            logConfigurator.setFileName(Environment.getExternalStorageDirectory() + File.separator + "msgant.log");
        } else {
            logConfigurator.setUseFileAppender(false);
        }
        logConfigurator.setRootLevel(Level.DEBUG);
        // Set log level of a specific logger
        logConfigurator.setLevel("org.apache", Level.ERROR);
        logConfigurator.configure();

        configured = true;
    }
}

It is far from a perfect solution, and actually, it will not solve my current issue with log4j crash, because I can not decide when users try to unmount SD-Card.

Or I should make a wrapper around log4j, and implement the storage detection logic there?

Answer 1

you can always listen to the sdcard events and reconfigure log4j accordingly.

<receiver android:name="com.project.events.SdCardEventListener" >
    <intent-filter>
        <action android:name="android.intent.action.MEDIA_REMOVED" />
        <action android:name="android.intent.action.MEDIA_MOUNTED" />
    </intent-filter>
</receiver>

this will allow you to reconfigure log4j when the card is removed (you can probably use the device internal storage till such a time a SD card is inserted again.

The SdCardEventListener should extend BroadcastReceiver and then reconfigure the logger as necessary.