我是log4j的新手。有人可以解释一下如何创建自己的Appender吗?即如何实现类和接口以及如何覆盖它?
public /*static*/ class MyAppender extends AppenderSkeleton {
ArrayList<LoggingEvent> eventsList = new ArrayList();
@Override
protected void append(LoggingEvent event) {
eventsList.add(event);
}
public void close() {
}
public boolean requiresLayout() {
return false;
}
}
好的,让我们来测试一下:
public static void main (String [] args) {
Logger l = Logger.getLogger("test");
MyAppender app = new MyAppender();
l.addAppender(app);
l.warn("first");
l.warn("second");
l.warn("third");
l.trace("fourth shouldn't be printed");
for (LoggingEvent le: app.eventsList) {
System.out.println("***" + le.getMessage());
}
}
@Override
protected void append(LoggingEvent event) {
String message = null;
if(event.locationInformationExists()){
StringBuilder formatedMessage = new StringBuilder();
formatedMessage.append(event.getLocationInformation().getClassName());
formatedMessage.append(".");
formatedMessage.append(event.getLocationInformation().getMethodName());
formatedMessage.append(":");
formatedMessage.append(event.getLocationInformation().getLineNumber());
formatedMessage.append(" - ");
formatedMessage.append(event.getMessage().toString());
message = formatedMessage.toString();
}else{
message = event.getMessage().toString();
}
switch(event.getLevel().toInt()){
case Level.INFO_INT:
//your decision
break;
case Level.DEBUG_INT:
//your decision
break;
case Level.ERROR_INT:
//your decision
break;
case Level.WARN_INT:
//your decision
break;
case Level.TRACE_INT:
//your decision
break;
default:
//your decision
break;
}
}
public class StringBufferAppender extends org.apache.log4j.AppenderSkeleton {
StringBuffer logs = new StringBuffer();
AtomicBoolean captureMode = new AtomicBoolean(false);
public void close() {
// TODO Auto-generated method stub
}
public boolean requiresLayout() {
// TODO Auto-generated method stub
return false;
}
@Override
protected void append(LoggingEvent event) {
if(captureMode.get())
logs.append(event.getMessage());
}
public void start()
{
//System.out.println("[StringBufferAppender|start] - Start capturing logs");
StringBuffer logs = new StringBuffer();
captureMode.set(true);
}
public StringBuffer stop()
{
//System.out.println("[StringBufferAppender|start] - Stop capturing logs");
captureMode.set(false);
StringBuffer data = new StringBuffer(logs);
logs = null;
return data;
}
}
log4j.rootLogger=...., myAppender # here you adding your appendr name
log4j.appender.myAppender=com.roi.log.StringBufferAppender # pointing it to the implementation
如果您想在运行时启用它:
Logger logger = Logger.getRootLogger();
StringBufferAppender appender = (StringBufferAppender)logger.getAppender("myAppender");
appender.start();
当您想要停止它时:
StringBuffer sb = appender.stop();
append(LoggingEvent event)
方法时,出现错误 - MyCustomAppender
类型的append(LoggingEvent)
方法必须覆盖或实现超类型方法。 - Chetan Oswal