Google App Engine - default registrar setting for sending email

Question

In my GAE / J app, how do I set up a default logger for email error reporting?

Answer 1

SMTPHandler already exists, but cannot be used with GAE / J due to unsatisfied dependencies. Take a look at the source code of SMTPHandler and adapt it to GAE / J.

Answer 2

MailHandler , included in JavaMail 1.5.3 and later built in support for Google App Engine . Make sure you are using the latest version of JavaMail.

For GAE / J, you can download logging-mailhandler.jar and include it in your project.

<dependency> <groupId>com.sun.mail</groupId> <artifactId>logging-mailhandler</artifactId> <version>1.5.3</version> <scope>system</scope> <systemPath>FILE_PATH_TO/logging-mailhandler.jar</systemPath> </dependency> 

Otherwise, you can use the java.net Maven or Maven Central repository and pull the dependency using groupid = com.sun.mail and artifactId = logging-mailhandler.

 <dependency> <groupId>com.sun.mail</groupId> <artifactId>logging-mailhandler</artifactId> <version>1.5.3</version> </dependency> 

After the dependency setting is configured, configure the logging settings so that they contain the correct logging and email envlope settings. Here is an example logging.properties file:

  # A default java.util.logging configuration. # (All App Engine logging is through java.util.logging by default). # # To use this configuration, copy it into your application WEB-INF # folder and add the following to your appengine-web.xml: # # <system-properties> # <property name="java.util.logging.config.file" value="WEB-INF/logging.properties"/> # </system-properties> # # Set the default logging level for all loggers to INFO .level = INFO java.util.logging.MemoryHandler.level=ALL java.util.logging.MemoryHandler.push=WARNING #com.sun.mail.util.logging.CompactFormatter.format=%1$tc %2$s%n%4$s: %5$s%6$s%n #com.sun.mail.util.logging.MailHandler.formatter=com.sun.mail.util.logging.CompactFormatter com.sun.mail.util.logging.MailHandler.level=WARNING com.sun.mail.util.logging.MailHandler.mail.from=[e-mail] com.sun.mail.util.logging.MailHandler.mail.to=[e-mail] #com.sun.mail.util.logging.MailHandler.pushLevel=OFF #com.sun.mail.util.logging.MailHandler.subject=com.sun.mail.util.logging.CollectorFormatter com.sun.mail.util.logging.MailHandler.verify=limited 

Next, create code to install MailHandler , because LogManager won. Unable to see logging-mailhandler.jar .

Here is an example ServletContextListener that will install MailHandler in the root log.

 /** * Modify web.xml to include * <listener> * <description>Install MailHandler on root logger.</description> * <listener-class>PACKAGE_NAME_FOR.MailHandlerConfig</listener-class> * </listener> */ import com.sun.mail.util.logging.*; import static com.google.appengine.api.ThreadManager.backgroundThreadFactory; import java.util.Arrays; import static java.util.concurrent.Executors.newScheduledThreadPool; import java.util.concurrent.Future; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; import java.util.logging.Formatter; import java.util.logging.Handler; import java.util.logging.Level; import java.util.logging.Logger; import java.util.logging.MemoryHandler; import javax.servlet.ServletContextEvent; import javax.servlet.ServletContextListener; public class MailHandlerConfig implements ServletContextListener, Runnable { private static final String LOGGER_NAME = ""; private static final Logger logger = Logger.getLogger(LOGGER_NAME); private volatile ScheduledExecutorService ses; private volatile Future<?> task; private volatile Handler handler; @Override public void contextInitialized(ServletContextEvent sce) { MailHandler mh = new MailHandler(); mh.setSubject(defaultSubject()); handler = mh; try { handler = new MemoryHandler(mh, mh.getCapacity(), mh.getPushLevel()); ses = newScheduledThreadPool(1, backgroundThreadFactory()); task = ses.scheduleAtFixedRate(this, 30L, 30L, TimeUnit.MINUTES); } catch (RuntimeException | LinkageError re) { logger.log(Level.WARNING, "Unable to create push thread.", re); Level lvl = mh.getLevel(); if (lvl.intValue() < mh.getPushLevel().intValue()) { mh.setPushLevel(lvl); handler = mh; logger.log(Level.WARNING, "Forcing push level to {0}.", lvl); } } logger.addHandler(handler); logger.log(Level.INFO, "Application initialized. {0}", Arrays.toString(logger.getHandlers())); } @Override public void contextDestroyed(ServletContextEvent sce) { //Never called under GAE. try { Future<?> f = task; if (f != null) { f.cancel(false); } } catch (RuntimeException ignore) { } try { ScheduledExecutorService e = this.ses; if (e != null) { e.shutdown(); } } catch (RuntimeException ignore) { } try { Handler h = handler; if (h != null) { h.close(); logger.removeHandler(h); } } catch (RuntimeException ignore) { } run(); } @Override public void run() { for (Handler h : logger.getHandlers()) { try { if (h instanceof MemoryHandler) { ((MemoryHandler) h).push(); } h.flush(); } catch (RuntimeException ignore) { } } } private static Formatter defaultSubject() { return new CollectorFormatter( "{0}{1}{2}{4,choice,-1#|0#|0<... {4,number,integer} more}", new CompactFormatter("%7$#.160s"), new SeverityComparator()); } }