AppenderSkeleton有一个抽象方法:
protected abstract void append(LoggingEvent event)
protected void subAppend(LoggingEvent event) {
this.qw.write(this.layout.format(event));
if (layout.ignoresThrowable()) {
String[] s = event.getThrowableStrRep();
if (s != null) {
int len = s.length;
for (int i = 0; i < len; i++) {
this.qw.write(s[i]);
this.qw.write(Layout.LINE_SEP);
}
}
}
if (this.immediateFlush) {
this.qw.flush();
}
}
this.qw.write(this.layout.format(event));
if (layout.ignoresThrowable()) {
String[] s = event.getThrowableStrRep();
if (s != null) {
int len = s.length;
for (int i = 0; i < len; i++) {
this.qw.write(s[i]);
this.qw.write(Layout.LINE_SEP);
}
}
}
if (this.immediateFlush) {
this.qw.flush();
}
}
写好自已的类后就可以在log4j.properties配置文件中把log4j.appender的值赋为该类名。然后log4j启动读入配置文件就会使用自定义的Appender了!