Java 类org.apache.log4j.spi.ThrowableInformation 实例源码

@Test
public void testException() throws Throwable {
  Exception e =
      new NoRouteToHostException("that box caught fire 3 years ago");
  ThrowableInformation ti = new ThrowableInformation(e);
  Log4Json l4j = new Log4Json();
  long timeStamp = Time.now();
  String outcome = l4j.toJson(new StringWriter(),
      "testException",
      timeStamp,
      "INFO",
      "quoted\"",
      "new line\n and {}",
      ti)
      .toString();
  println("testException", outcome);
}

private String getLoggingMesage( LoggingEvent event ) {

        Throwable throwable = null;
        ThrowableInformation throwableInfo = event.getThrowableInformation();
        if (throwableInfo != null && throwableInfo.getThrowable() != null) {
            // logging through methods like error(new Exception);
            throwable = throwableInfo.getThrowable();
        } else if (event.getMessage() instanceof Throwable) {
            // logging through methods like error("some message", new Exception);
            throwable = (Throwable) event.getMessage();
        }

        // first format the message using the layout
        String message = layout.format(event);
        // then append the exception stack trace
        if (throwable != null) {
            message = getExceptionMsg(throwable, message);
        }

        return message;

    }

@Test
public void testException() throws Throwable {
  Exception e =
      new NoRouteToHostException("that box caught fire 3 years ago");
  ThrowableInformation ti = new ThrowableInformation(e);
  Log4Json l4j = new Log4Json();
  long timeStamp = Time.now();
  String outcome = l4j.toJson(new StringWriter(),
      "testException",
      timeStamp,
      "INFO",
      "quoted\"",
      "new line\n and {}",
      ti)
      .toString();
  println("testException", outcome);
}

/**
 * Extracts Stack trace of Throwable contained in LogginEvent, if there is
 * any
 * 
 * @param aLoggingEvent
 *            logging event
 * @return stack trace of throwable
 */
public String getThrowableRepresentationFromLoggingEvent(LoggingEvent aLoggingEvent) {
    // extract throwable information from loggingEvent if available
    ThrowableInformation throwableinfo = aLoggingEvent.getThrowableInformation();
    StringBuffer throwableStringBuffer = new StringBuffer();

    if (throwableinfo != null) {
        String[] lines = throwableinfo.getThrowableStrRep();
        for (int index = 0; index < lines.length; index++) {
            throwableStringBuffer = (StringBuffer) throwableStringBuffer.append(lines[index]
                    + "\r\n");
        }
    }
    String result = quotedString(throwableStringBuffer.toString());
    if (this.getThrowableMaxChars() != -1 && result.length() > this.getThrowableMaxChars()) {
        result = result.substring(0, this.getThrowableMaxChars() - 1);
    }

    return result;
}

@Test
public void testException() throws Throwable {
  Exception e =
      new NoRouteToHostException("that box caught fire 3 years ago");
  ThrowableInformation ti = new ThrowableInformation(e);
  Log4Json l4j = new Log4Json();
  long timeStamp = Time.now();
  String outcome = l4j.toJson(new StringWriter(),
      "testException",
      timeStamp,
      "INFO",
      "quoted\"",
      "new line\n and {}",
      ti)
      .toString();
  println("testException", outcome);
}

protected void alarm(LoggingEvent event, String level) {
    String message = event.getRenderedMessage();
    Throwable t = null;
    {
        ThrowableInformation throwableInformation = event.getThrowableInformation();
        if (throwableInformation != null) {
            t = throwableInformation.getThrowable();
        }
    }

    try {
        // this.sendToRobot(message, t);
        this.robotService.errorlog(level, message, t);
    }
    catch (Exception e) {
        e.printStackTrace();

    }
}

@Test
public void testException() throws Throwable {
  Exception e =
      new NoRouteToHostException("that box caught fire 3 years ago");
  ThrowableInformation ti = new ThrowableInformation(e);
  Log4Json l4j = new Log4Json();
  long timeStamp = Time.now();
  String outcome = l4j.toJson(new StringWriter(),
      "testException",
      timeStamp,
      "INFO",
      "quoted\"",
      "new line\n and {}",
      ti)
      .toString();
  println("testException", outcome);
}

@Test
public void testException() throws Throwable {
  Exception e =
      new NoRouteToHostException("that box caught fire 3 years ago");
  ThrowableInformation ti = new ThrowableInformation(e);
  Log4Json l4j = new Log4Json();
  long timeStamp = Time.now();
  String outcome = l4j.toJson(new StringWriter(),
      "testException",
      timeStamp,
      "INFO",
      "quoted\"",
      "new line\n and {}",
      ti)
      .toString();
  println("testException", outcome);
}

@Override
protected void append(final LoggingEvent loggingEvent) {
    final StringBuilder buf = new StringBuilder();
    buf.append(getLayout().format(loggingEvent));
    final ThrowableInformation ti = loggingEvent.getThrowableInformation();

    if (ti != null) {
        final String[] cause = ti.getThrowableStrRep();

        for (final String line : cause) {
            buf.append(line).append('\n');
        }
    }

    j2DClient.get().addEventLine(new HeaderLessEventLine(buf.toString(), NotificationType.CLIENT));
}

@Test
public void testException() throws Throwable {
  Exception e =
      new NoRouteToHostException("that box caught fire 3 years ago");
  ThrowableInformation ti = new ThrowableInformation(e);
  Log4Json l4j = new Log4Json();
  long timeStamp = Time.now();
  String outcome = l4j.toJson(new StringWriter(),
      "testException",
      timeStamp,
      "INFO",
      "quoted\"",
      "new line\n and {}",
      ti)
      .toString();
  println("testException", outcome);
}

/**
 * {@inheritDoc}
 */
public void format(final LoggingEvent event, final StringBuffer toAppendTo) {
  if (maxLines != 0) {
    ThrowableInformation information = event.getThrowableInformation();

    if (information != null) {
      String[] stringRep = information.getThrowableStrRep();

      int length = stringRep.length;
      if (maxLines < 0) {
          length += maxLines;
      } else if (length > maxLines) {
          length = maxLines;
      }

      for (int i = 0; i < length; i++) {
          String string = stringRep[i];
          toAppendTo.append(string).append("\n");
      }
    }
  }
}

@Test
public void testException() throws Throwable {
  Exception e =
      new NoRouteToHostException("that box caught fire 3 years ago");
  ThrowableInformation ti = new ThrowableInformation(e);
  Log4Json l4j = new Log4Json();
  long timeStamp = Time.now();
  String outcome = l4j.toJson(new StringWriter(),
      "testException",
      timeStamp,
      "INFO",
      "quoted\"",
      "new line\n and {}",
      ti)
      .toString();
  println("testException", outcome);
}

@BeforeClass
public static void setupBeforeClass() throws Exception {
    Logger xenqtt = Logger.getLogger("xenqtt");
    assertNotNull(xenqtt);

    Appender console = Logger.getRootLogger().getAppender("console");
    assertNotNull(console);

    console.addFilter(new Filter() {
        @Override
        public int decide(LoggingEvent event) {
            entries.add(event.getRenderedMessage());

            ThrowableInformation info = event.getThrowableInformation();
            if (info != null) {
                Throwable t = info.getThrowable();
                if (t != null) {
                    entries.add(t.getMessage());
                }
            }

            return Filter.ACCEPT;
        }
    });
}

@Test
public void testException() throws Throwable {
  Exception e =
      new NoRouteToHostException("that box caught fire 3 years ago");
  ThrowableInformation ti = new ThrowableInformation(e);
  Log4Json l4j = new Log4Json();
  long timeStamp = Time.now();
  String outcome = l4j.toJson(new StringWriter(),
      "testException",
      timeStamp,
      "INFO",
      "quoted\"",
      "new line\n and {}",
      ti)
      .toString();
  println("testException", outcome);
}

/**
 * @see com.stackify.api.common.log.EventAdapter#getThrowable(java.lang.Object)
 */
@Override
public Throwable getThrowable(final LoggingEvent event) {

    ThrowableInformation throwableInfo = event.getThrowableInformation();

    if (throwableInfo != null) {
        Throwable t = throwableInfo.getThrowable();

        if (t != null) {
            return t;
        }
    }

    Object message = event.getMessage();

    if (message != null) {
        if (message instanceof Throwable) {
            return (Throwable) message;
        }
    }

    return null;
}

@Test
public void testException() throws Throwable {
  Exception e =
      new NoRouteToHostException("that box caught fire 3 years ago");
  ThrowableInformation ti = new ThrowableInformation(e);
  Log4Json l4j = new Log4Json();
  long timeStamp = Time.now();
  String outcome = l4j.toJson(new StringWriter(),
      "testException",
      timeStamp,
      "INFO",
      "quoted\"",
      "new line\n and {}",
      ti)
      .toString();
  println("testException", outcome);
}

@Test
public void testException() throws Throwable {
  Exception e =
      new NoRouteToHostException("that box caught fire 3 years ago");
  ThrowableInformation ti = new ThrowableInformation(e);
  Log4Json l4j = new Log4Json();
  long timeStamp = Time.now();
  String outcome = l4j.toJson(new StringWriter(),
      "testException",
      timeStamp,
      "INFO",
      "quoted\"",
      "new line\n and {}",
      ti)
      .toString();
  println("testException", outcome);
}

/**
 * Prepares the LoggingEvent for beeing processes in another thread, by saving away the NDC, MDC, thread name,  
 * throwable information and location information (if parameter getLocationInformation is true).   
 * 
 * @param loggingEvent the logging event to prepare.
 * @param getLocationInformation flag indicating if location information should be fetched for the logging event.
 * 
 * @since 2.0
 */
public static void prepareLoggingEvent(final LoggingEvent loggingEvent, final boolean getLocationInformation)
{
   // Set the NDC and thread name for the calling thread as these LoggingEvent fields were not set at event creation time.
   loggingEvent.getNDC();
   loggingEvent.getThreadName();
   // Get a copy of this thread's MDC.
   loggingEvent.getMDCCopy();
   ThrowableInformation throwableInformation =  loggingEvent.getThrowableInformation();
   if( throwableInformation != null )
   {
      // Make the ThrowableInformation of the LoggingEvent store away the representation of the stack trace.
      throwableInformation.getThrowableStrRep();
   }
   if( getLocationInformation ) 
   {
      loggingEvent.getLocationInformation();
   }
}

public String convert(LoggingEvent event) 
{
   ThrowableInformation throwableInformation = event.getThrowableInformation();
   if(throwableInformation != null)
   {
      Throwable error = throwableInformation.getThrowable();
      if( error != null )
      {
         StringWriter strWriter = new StringWriter();
         error.printStackTrace(new PrintWriter(strWriter));

         return strWriter.toString().replaceAll("\\s+", " ");
      }
   }

   return "";
}

public static String getThrowable(LoggingEvent le)
{
    ThrowableInformation tinfo = le.getThrowableInformation();
    Throwable t = null;
    try
    {
        t = tinfo.getThrowable();
    }
    catch (Exception ex)
    {
    }

    if (t == null)
    {
        return "";
    }

    java.io.StringWriter stringWriter;
    stringWriter = new java.io.StringWriter();
    t.printStackTrace(new java.io.PrintWriter(stringWriter));

    return stringWriter.getBuffer().toString();
}

/**
 * Pull out details of exception in a Hashmap (if they exist)
 * 
 * @param loggingEvent
 * @return
 */
protected void exceptionInformation(
        final LoggingEvent loggingEvent) {
    if (loggingEvent.getThrowableInformation() != null) {
        final ThrowableInformation throwableInformation = loggingEvent
                .getThrowableInformation();
        if (throwableInformation.getThrowable().getClass()
                .getCanonicalName() != null) {
            ExceptionField.put(EXCEPTION.CLASS, throwableInformation.getThrowable().getClass()
                    .getCanonicalName());
        }
        if (throwableInformation.getThrowable().getMessage() != null) {
            ExceptionField.put(EXCEPTION.MESSAGE, throwableInformation.getThrowable().getMessage());
        }
        if (throwableInformation.getThrowableStrRep() != null) {
            final String stackTrace = StringUtils.join(
                    throwableInformation.getThrowableStrRep(), "\n");
            ExceptionField.put(EXCEPTION.STACKTRACE, stackTrace);
        }
    }
}

public static String getThrowable(LoggingEvent le)
{
    ThrowableInformation tinfo = le.getThrowableInformation();
    Throwable t = null;
    try
    {
        t = tinfo.getThrowable();
    }
    catch (Exception ex)
    {
    }

    if (t == null)
    {
        return "";
    }

    java.io.StringWriter stringWriter;
    stringWriter = new java.io.StringWriter();
    t.printStackTrace(new java.io.PrintWriter(stringWriter));

    return stringWriter.getBuffer().toString();
}

public static String getThrowable(LoggingEvent le)
{
    ThrowableInformation tinfo = le.getThrowableInformation();
    Throwable t = null;
    try
    {
        t = tinfo.getThrowable();
    }
    catch (Exception ex)
    {
    }

    if (t == null)
    {
        return "";
    }

    java.io.StringWriter stringWriter;
    stringWriter = new java.io.StringWriter();
    t.printStackTrace(new java.io.PrintWriter(stringWriter));

    return stringWriter.getBuffer().toString();
}

/**
 * Convert an event to JSON
 *
 * @param writer the destination writer
 * @param event the event -must not be null
 * @return the writer
 * @throws IOException on problems generating the JSON
 */
public Writer toJson(final Writer writer, final LoggingEvent event)
    throws IOException {
  ThrowableInformation ti = event.getThrowableInformation();
  toJson(writer,
         event.getLoggerName(),
         event.getTimeStamp(),
         event.getLevel().toString(),
         event.getThreadName(),
         event.getRenderedMessage(),
         ti);
  return writer;
}

/**
 * Build a JSON entry from the parameters. This is public for testing.
 *
 * @param writer destination
 * @param loggerName logger name
 * @param timeStamp time_t value
 * @param level level string
 * @param threadName name of the thread
 * @param message rendered message
 * @param ti nullable thrown information
 * @return the writer
 * @throws IOException on any problem
 */
public Writer toJson(final Writer writer,
                     final String loggerName,
                     final long timeStamp,
                     final String level,
                     final String threadName,
                     final String message,
                     final ThrowableInformation ti) throws IOException {
  JsonGenerator json = factory.createJsonGenerator(writer);
  json.writeStartObject();
  json.writeStringField(NAME, loggerName);
  json.writeNumberField(TIME, timeStamp);
  Date date = new Date(timeStamp);
  json.writeStringField(DATE, dateFormat.format(date));
  json.writeStringField(LEVEL, level);
  json.writeStringField(THREAD, threadName);
  json.writeStringField(MESSAGE, message);
  if (ti != null) {
    //there is some throwable info, but if the log event has been sent over the wire,
    //there may not be a throwable inside it, just a summary.
    Throwable thrown = ti.getThrowable();
    String eclass = (thrown != null) ?
        thrown.getClass().getName()
        : "";
    json.writeStringField(EXCEPTION_CLASS, eclass);
    String[] stackTrace = ti.getThrowableStrRep();
    json.writeArrayFieldStart(STACK);
    for (String row : stackTrace) {
      json.writeString(row);
    }
    json.writeEndArray();
  }
  json.writeEndObject();
  json.flush();
  json.close();
  return writer;
}

@Test
public void testNestedException() throws Throwable {
  Exception e =
      new NoRouteToHostException("that box caught fire 3 years ago");
  Exception ioe = new IOException("Datacenter problems", e);
  ThrowableInformation ti = new ThrowableInformation(ioe);
  Log4Json l4j = new Log4Json();
  long timeStamp = Time.now();
  String outcome = l4j.toJson(new StringWriter(),
      "testNestedException",
      timeStamp,
      "INFO",
      "quoted\"",
      "new line\n and {}",
      ti)
      .toString();
  println("testNestedException", outcome);
  ContainerNode rootNode = Log4Json.parse(outcome);
  assertEntryEquals(rootNode, Log4Json.LEVEL, "INFO");
  assertEntryEquals(rootNode, Log4Json.NAME, "testNestedException");
  assertEntryEquals(rootNode, Log4Json.TIME, timeStamp);
  assertEntryEquals(rootNode, Log4Json.EXCEPTION_CLASS,
      ioe.getClass().getName());
  JsonNode node = assertNodeContains(rootNode, Log4Json.STACK);
  assertTrue("Not an array: " + node, node.isArray());
  node = assertNodeContains(rootNode, Log4Json.DATE);
  assertTrue("Not a string: " + node, node.isTextual());
  //rather than try and make assertions about the format of the text
  //message equalling another ISO date, this test asserts that the hypen
  //and colon characters are in the string.
  String dateText = node.getTextValue();
  assertTrue("No '-' in " + dateText, dateText.contains("-"));
  assertTrue("No '-' in " + dateText, dateText.contains(":"));

}

public void appendersCalled(LoggingEvent event) {
  ThrowableInformation throwableInfo = event.getThrowableInformation();
  String throwableName = null;
  if (throwableInfo != null) {
    Throwable throwable = throwableInfo.getThrowable();
    throwableName = (throwable != null) ? throwable.getClass().getName() : null;
  }
  LogEventTracker.LogLevel level = LogEventTracker.LogLevel.valueOf(event.getLevel().toString());
  tracker.track(level, (throwableInfo != null), throwableName);

}

public int countExceptionsWithMessage(final String text) {
  int count = 0;
  for (LoggingEvent e: getLog()) {
    ThrowableInformation t = e.getThrowableInformation();
    if (t != null) {
      String m = t.getThrowable().getMessage();
      if (m.contains(text)) {
        count++;
      }
    }
  }
  return count;
}

/**
 * Convert an event to JSON
 *
 * @param writer the destination writer
 * @param event the event -must not be null
 * @return the writer
 * @throws IOException on problems generating the JSON
 */
public Writer toJson(final Writer writer, final LoggingEvent event)
    throws IOException {
  ThrowableInformation ti = event.getThrowableInformation();
  toJson(writer,
         event.getLoggerName(),
         event.getTimeStamp(),
         event.getLevel().toString(),
         event.getThreadName(),
         event.getRenderedMessage(),
         ti);
  return writer;
}

/**
 * Build a JSON entry from the parameters. This is public for testing.
 *
 * @param writer destination
 * @param loggerName logger name
 * @param timeStamp time_t value
 * @param level level string
 * @param threadName name of the thread
 * @param message rendered message
 * @param ti nullable thrown information
 * @return the writer
 * @throws IOException on any problem
 */
public Writer toJson(final Writer writer,
                     final String loggerName,
                     final long timeStamp,
                     final String level,
                     final String threadName,
                     final String message,
                     final ThrowableInformation ti) throws IOException {
  JsonGenerator json = factory.createJsonGenerator(writer);
  json.writeStartObject();
  json.writeStringField(NAME, loggerName);
  json.writeNumberField(TIME, timeStamp);
  Date date = new Date(timeStamp);
  json.writeStringField(DATE, dateFormat.format(date));
  json.writeStringField(LEVEL, level);
  json.writeStringField(THREAD, threadName);
  json.writeStringField(MESSAGE, message);
  if (ti != null) {
    //there is some throwable info, but if the log event has been sent over the wire,
    //there may not be a throwable inside it, just a summary.
    Throwable thrown = ti.getThrowable();
    String eclass = (thrown != null) ?
        thrown.getClass().getName()
        : "";
    json.writeStringField(EXCEPTION_CLASS, eclass);
    String[] stackTrace = ti.getThrowableStrRep();
    json.writeArrayFieldStart(STACK);
    for (String row : stackTrace) {
      json.writeString(row);
    }
    json.writeEndArray();
  }
  json.writeEndObject();
  json.flush();
  json.close();
  return writer;
}

@Test
public void testNestedException() throws Throwable {
  Exception e =
      new NoRouteToHostException("that box caught fire 3 years ago");
  Exception ioe = new IOException("Datacenter problems", e);
  ThrowableInformation ti = new ThrowableInformation(ioe);
  Log4Json l4j = new Log4Json();
  long timeStamp = Time.now();
  String outcome = l4j.toJson(new StringWriter(),
      "testNestedException",
      timeStamp,
      "INFO",
      "quoted\"",
      "new line\n and {}",
      ti)
      .toString();
  println("testNestedException", outcome);
  ContainerNode rootNode = Log4Json.parse(outcome);
  assertEntryEquals(rootNode, Log4Json.LEVEL, "INFO");
  assertEntryEquals(rootNode, Log4Json.NAME, "testNestedException");
  assertEntryEquals(rootNode, Log4Json.TIME, timeStamp);
  assertEntryEquals(rootNode, Log4Json.EXCEPTION_CLASS,
      ioe.getClass().getName());
  JsonNode node = assertNodeContains(rootNode, Log4Json.STACK);
  assertTrue("Not an array: " + node, node.isArray());
  node = assertNodeContains(rootNode, Log4Json.DATE);
  assertTrue("Not a string: " + node, node.isTextual());
  //rather than try and make assertions about the format of the text
  //message equalling another ISO date, this test asserts that the hypen
  //and colon characters are in the string.
  String dateText = node.getTextValue();
  assertTrue("No '-' in " + dateText, dateText.contains("-"));
  assertTrue("No '-' in " + dateText, dateText.contains(":"));

}

public int countExceptionsWithMessage(final String text) {
  int count = 0;
  for (LoggingEvent e: getLog()) {
    ThrowableInformation t = e.getThrowableInformation();
    if (t != null) {
      String m = t.getThrowable().getMessage();
      if (m.contains(text)) {
        count++;
      }
    }
  }
  return count;
}

/**
 * Convert an event to JSON
 *
 * @param writer the destination writer
 * @param event the event -must not be null
 * @return the writer
 * @throws IOException on problems generating the JSON
 */
public Writer toJson(final Writer writer, final LoggingEvent event)
    throws IOException {
  ThrowableInformation ti = event.getThrowableInformation();
  toJson(writer,
         event.getLoggerName(),
         event.getTimeStamp(),
         event.getLevel().toString(),
         event.getThreadName(),
         event.getRenderedMessage(),
         ti);
  return writer;
}

/**
 * Build a JSON entry from the parameters. This is public for testing.
 *
 * @param writer destination
 * @param loggerName logger name
 * @param timeStamp time_t value
 * @param level level string
 * @param threadName name of the thread
 * @param message rendered message
 * @param ti nullable thrown information
 * @return the writer
 * @throws IOException on any problem
 */
public Writer toJson(final Writer writer,
                     final String loggerName,
                     final long timeStamp,
                     final String level,
                     final String threadName,
                     final String message,
                     final ThrowableInformation ti) throws IOException {
  JsonGenerator json = factory.createJsonGenerator(writer);
  json.writeStartObject();
  json.writeStringField(NAME, loggerName);
  json.writeNumberField(TIME, timeStamp);
  Date date = new Date(timeStamp);
  json.writeStringField(DATE, dateFormat.format(date));
  json.writeStringField(LEVEL, level);
  json.writeStringField(THREAD, threadName);
  json.writeStringField(MESSAGE, message);
  if (ti != null) {
    //there is some throwable info, but if the log event has been sent over the wire,
    //there may not be a throwable inside it, just a summary.
    Throwable thrown = ti.getThrowable();
    String eclass = (thrown != null) ?
        thrown.getClass().getName()
        : "";
    json.writeStringField(EXCEPTION_CLASS, eclass);
    String[] stackTrace = ti.getThrowableStrRep();
    json.writeArrayFieldStart(STACK);
    for (String row : stackTrace) {
      json.writeString(row);
    }
    json.writeEndArray();
  }
  json.writeEndObject();
  json.flush();
  json.close();
  return writer;
}

@Test
public void testNestedException() throws Throwable {
  Exception e =
      new NoRouteToHostException("that box caught fire 3 years ago");
  Exception ioe = new IOException("Datacenter problems", e);
  ThrowableInformation ti = new ThrowableInformation(ioe);
  Log4Json l4j = new Log4Json();
  long timeStamp = Time.now();
  String outcome = l4j.toJson(new StringWriter(),
      "testNestedException",
      timeStamp,
      "INFO",
      "quoted\"",
      "new line\n and {}",
      ti)
      .toString();
  println("testNestedException", outcome);
  ContainerNode rootNode = Log4Json.parse(outcome);
  assertEntryEquals(rootNode, Log4Json.LEVEL, "INFO");
  assertEntryEquals(rootNode, Log4Json.NAME, "testNestedException");
  assertEntryEquals(rootNode, Log4Json.TIME, timeStamp);
  assertEntryEquals(rootNode, Log4Json.EXCEPTION_CLASS,
      ioe.getClass().getName());
  JsonNode node = assertNodeContains(rootNode, Log4Json.STACK);
  assertTrue("Not an array: " + node, node.isArray());
  node = assertNodeContains(rootNode, Log4Json.DATE);
  assertTrue("Not a string: " + node, node.isTextual());
  //rather than try and make assertions about the format of the text
  //message equalling another ISO date, this test asserts that the hypen
  //and colon characters are in the string.
  String dateText = node.getTextValue();
  assertTrue("No '-' in " + dateText, dateText.contains("-"));
  assertTrue("No '-' in " + dateText, dateText.contains(":"));

}

@Override
public String format(LoggingEvent event) {
  BenderLogEntry entry = new BenderLogEntry();
  entry.threadName = event.getThreadName();
  entry.posixTimestamp = event.getTimeStamp();
  entry.timestamp = FORMATTER.print(entry.posixTimestamp);
  entry.message = event.getRenderedMessage();
  entry.level = event.getLevel().toString();
  entry.logger = event.getLogger().getName();
  entry.alias = ALIAS;
  entry.version = VERSION;

  if (event.getThrowableInformation() != null) {
    final ThrowableInformation throwableInfo = event.getThrowableInformation();
    ExceptionLog ex = new ExceptionLog();

    if (throwableInfo.getThrowable().getClass().getCanonicalName() != null) {
      ex.clazz = throwableInfo.getThrowable().getClass().getCanonicalName();
    }
    if (throwableInfo.getThrowable().getMessage() != null) {
      ex.message = throwableInfo.getThrowable().getMessage();
    }
    if (throwableInfo.getThrowableStrRep() != null) {
      Arrays.asList(throwableInfo.getThrowableStrRep()).forEach(m -> {
        ex.stacktrace.add(m.replaceAll("\\t", "   "));
      });
    }
    entry.exception = ex;
  }

  LocationInfo locinfo = event.getLocationInformation();
  entry.file = locinfo.getFileName();
  entry.lineNumber = Integer.parseInt(locinfo.getLineNumber());
  entry.method = locinfo.getMethodName();
  entry.clazz = locinfo.getClassName();

  return GSON.toJson(entry) + "\n";
}

public int countExceptionsWithMessage(final String text) {
  int count = 0;
  for (LoggingEvent e: getLog()) {
    ThrowableInformation t = e.getThrowableInformation();
    if (t != null) {
      String m = t.getThrowable().getMessage();
      if (m.contains(text)) {
        count++;
      }
    }
  }
  return count;
}

/**
 * Convert an event to JSON
 *
 * @param writer the destination writer
 * @param event the event -must not be null
 * @return the writer
 * @throws IOException on problems generating the JSON
 */
public Writer toJson(final Writer writer, final LoggingEvent event)
    throws IOException {
  ThrowableInformation ti = event.getThrowableInformation();
  toJson(writer,
         event.getLoggerName(),
         event.getTimeStamp(),
         event.getLevel().toString(),
         event.getThreadName(),
         event.getRenderedMessage(),
         ti);
  return writer;
}

/**
 * Build a JSON entry from the parameters. This is public for testing.
 *
 * @param writer destination
 * @param loggerName logger name
 * @param timeStamp time_t value
 * @param level level string
 * @param threadName name of the thread
 * @param message rendered message
 * @param ti nullable thrown information
 * @return the writer
 * @throws IOException on any problem
 */
public Writer toJson(final Writer writer,
                     final String loggerName,
                     final long timeStamp,
                     final String level,
                     final String threadName,
                     final String message,
                     final ThrowableInformation ti) throws IOException {
  JsonGenerator json = factory.createJsonGenerator(writer);
  json.writeStartObject();
  json.writeStringField(NAME, loggerName);
  json.writeNumberField(TIME, timeStamp);
  Date date = new Date(timeStamp);
  json.writeStringField(DATE, dateFormat.format(date));
  json.writeStringField(LEVEL, level);
  json.writeStringField(THREAD, threadName);
  json.writeStringField(MESSAGE, message);
  if (ti != null) {
    //there is some throwable info, but if the log event has been sent over the wire,
    //there may not be a throwable inside it, just a summary.
    Throwable thrown = ti.getThrowable();
    String eclass = (thrown != null) ?
        thrown.getClass().getName()
        : "";
    json.writeStringField(EXCEPTION_CLASS, eclass);
    String[] stackTrace = ti.getThrowableStrRep();
    json.writeArrayFieldStart(STACK);
    for (String row : stackTrace) {
      json.writeString(row);
    }
    json.writeEndArray();
  }
  json.writeEndObject();
  json.flush();
  json.close();
  return writer;
}

@Test
public void testNestedException() throws Throwable {
  Exception e =
      new NoRouteToHostException("that box caught fire 3 years ago");
  Exception ioe = new IOException("Datacenter problems", e);
  ThrowableInformation ti = new ThrowableInformation(ioe);
  Log4Json l4j = new Log4Json();
  long timeStamp = Time.now();
  String outcome = l4j.toJson(new StringWriter(),
      "testNestedException",
      timeStamp,
      "INFO",
      "quoted\"",
      "new line\n and {}",
      ti)
      .toString();
  println("testNestedException", outcome);
  ContainerNode rootNode = Log4Json.parse(outcome);
  assertEntryEquals(rootNode, Log4Json.LEVEL, "INFO");
  assertEntryEquals(rootNode, Log4Json.NAME, "testNestedException");
  assertEntryEquals(rootNode, Log4Json.TIME, timeStamp);
  assertEntryEquals(rootNode, Log4Json.EXCEPTION_CLASS,
      ioe.getClass().getName());
  JsonNode node = assertNodeContains(rootNode, Log4Json.STACK);
  assertTrue("Not an array: " + node, node.isArray());
  node = assertNodeContains(rootNode, Log4Json.DATE);
  assertTrue("Not a string: " + node, node.isTextual());
  //rather than try and make assertions about the format of the text
  //message equalling another ISO date, this test asserts that the hypen
  //and colon characters are in the string.
  String dateText = node.getTextValue();
  assertTrue("No '-' in " + dateText, dateText.contains("-"));
  assertTrue("No '-' in " + dateText, dateText.contains(":"));

}