A simple implementation of SLF4J API using Android java.util.logging.*. This means you can easily hook in any existing java.util.logging.Handler implementations.
To use this little gem, make sure you have Maven Central in your repositories:
repositories {
mavenCentral()
}and then declare a dependency inside a module:
dependencies {
// just SLF4J binding
implementation("dev.bright.slf4android:slf4android:$slf4androidVersion")
// (optional) a handler for file logging
implementation("dev.bright.slf4android:handler-file-log:$slf4androidVersion")
// (optional) a handler for notifying the developer in case of an error
implementation("dev.bright.slf4android:handler-notify-developer:$slf4androidVersion")
}As with any slf4j compatible implementation using slf4android looks like this:
class HomeActivity extends Activity {
private static final Logger LOG = LoggerFactory.getLogger(HomeActivity.class.getSimpleName());
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
LOG.debug("Hello from {} saved instance state {}", this, savedInstanceState);
}
}Crashlytics has a nice feature of attaching log entries that were issued just before a crash. With slf4android it's easy to add a handler so that whenever a crash happens you get more insight as to what happened just before it.
To achieve that you need a custom handler:
import com.crashlytics.android.Crashlytics;
import java.util.logging.Handler;
import pl.brightinventions.slf4android.LogRecord;
import pl.brightinventions.slf4android.MessageValueSupplier;
public class CrashlyticsLoggerHandler extends Handler {
MessageValueSupplier messageValueSupplier = new MessageValueSupplier();
@Override
public void publish(java.util.logging.LogRecord record) {
LogRecord logRecord = LogRecord.fromRecord(record);
StringBuilder messageBuilder = new StringBuilder();
messageValueSupplier.append(logRecord, messageBuilder);
String tag = record.getLoggerName();
int androidLogLevel = logRecord.getLogLevel().getAndroidLevel();
Crashlytics.log(androidLogLevel, tag, messageBuilder.toString());
}
@Override
public void close() {
}
@Override
public void flush() {
}
}That is added to root logger:
LoggerConfiguration.configuration()
.removeRootLogcatHandler()
.addHandlerToRootLogger(new CrashlyticsLoggerHandler());Note that we remove a default logcat handler since Crashlytics will push messages to logcat too.
To print messages to a separate file just add:
FileLogHandlerConfiguration fileHandler = FileLogHandlerConfiguration.create(this);
LoggerConfiguration.configuration().addHandlerToRootLogger(fileHandler);
String logFileName = fileHandler.getCurrentFileName();
// logFileName contains full path to logged fileinside your custom android.app.Application onCreate method. This will create rotated log files inside context.getApplicationInfo().dataDir with a name derived from context.getPackageName() and a default message pattern %date %level [%thread] %name - %message%newline
To change the location of log file you can use:
FileLogHandlerConfiguration fileHandler = FileLogHandlerConfiguration.create(this);
fileHandler.setFullFilePathPattern("/sdcard/your.package/my_log.%g.%u.log");
LoggerConfiguration.configuration().addHandlerToRootLogger(fileHandler);