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由于工作需要，最近对tomcat的日志进行了一些研究，发现其日志大致可以分为两类，一类是运行日志，即平常我们所说的catalina.out日志，由tomcat内部代码调用logger打印出来的；另一类是accesslog访问日志，即记录外部请求访问的信息。处理这两类日志，tomcat默认采用了不同的方式，运行类日志默认采用的是java.util.logging框架，由conf下的logging.properties负责配置管理，也可以支持切换到log4j2（具体可参看我的前一篇博文：升级tomcat7的运行日志框架到log4j2 ）；对于访问日志，tomcat默认是按日期直接写进文件，由server.xml中配置Valve来管理。
<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs" pattern="%h %l %u %t "%r" %s %b" prefix="localhost_access_log." suffix=".txt"/>
此配置会在logs下生成一个localhost_access_log.日期.txt，里面记录每次外部访问的一些信息，信息的内容是根据pattern来配置的，%后加不同的字母表示不同的信息，如上述默认的pattern配置会记录“访问端ip 用户名 时间 第一行请求内容 http状态码 发送字节大小”等内容，详细配置细节可以参考tomcat的accelog(url:https://tomcat.apache.org/tomcat-7.0-doc/config/valve.html#Access_Logging )
@Override public void log(Request request, Response response, long time) { if (!getState().isAvailable() || !getEnabled() || logElements == null || condition != null && null != request.getRequest().getAttribute(condition) || conditionIf != null && null == request.getRequest().getAttribute(conditionIf)) { return; } /** * XXX This is a bit silly, but we want to have start and stop time and * duration consistent. It would be better to keep start and stop * simply in the request and/or response object and remove time * (duration) from the interface. */ long start = request.getCoyoteRequest().getStartTime(); Date date = getDate(start + time); // 字符缓冲区 CharArrayWriter result = charArrayWriters.pop(); if (result == null) { result = new CharArrayWriter(128); } // pattern里不同的%表示不同的logElement，此处用result收集所有logElement里追加的内容 for (int i = 0; i < logElements.length; i++) { logElements[i].addElement(result, date, request, response, time); } // 写文件将result写入 log(result); if (result.size() <= maxLogMessageBufferSize) { result.reset(); charArrayWriters.push(result); } }
其中log(result)实现如下：
@Override public void log(CharArrayWriter message) { // 每个一秒检查一下是否需要切换文件 rotate(); // 如果存在文件，先关闭再重新打开一个新日期的文件 if (checkExists) { synchronized (this) { if (currentLogFile != null && !currentLogFile.exists()) { try { close(false); } catch (Throwable e) { ExceptionUtils.handleThrowable(e); log.info(sm.getString("accessLogValve.closeFail"), e); } /* Make sure date is correct */ dateStamp = fileDateFormatter.format( new Date(System.currentTimeMillis())); open(); } } } // Log this message 同步加锁写入日志文件，此处使用了buffer try { synchronized(this) { if (writer != null) { message.writeTo(writer); writer.println(""); if (!buffered) { writer.flush(); } } } } catch (IOException ioe) { log.warn(sm.getString( "accessLogValve.writeFail", message.toString()), ioe); } }
通过上述核心代码可以看到，默认的tomcat是利用缓冲写文件的方式进行访问日志记录的，如果需要分析访问日志，比如找出一天内有多少过ip访问过，或者某一个ip在一分钟内访问了多少次，一般的处理方式是读取accesslog文件内容并进行分析，这么做一方面是无法满足实时分析的目的，更重要的数据量大的时候会严重影响分析效率，因此我们需要对其进行扩展，比如我们可以把访问日志打到kafka或mango中。
@Override public void log(Request request, Response response, long time) { if (producerList != null && getEnabled() && getState().isAvailable() && null != this.accessLogElement) { try { getNextProducer().send(new ProducerRecord<byte[], byte[]>(topic, this.accessLogElement.buildLog(request,response,time,this).getBytes(StandardCharsets.UTF_8))).get(timeoutMillis, TimeUnit.MILLISECONDS); } catch (InterruptedException | ExecutionException | TimeoutException e) { log.error("accesslog in kafka exception", e); } } }
private String topic; private String bootstrapServers; // If set to zero then the producer will not wait for any acknowledgment from the server at all. private String acks; private String producerSize ; private String properties; private List<Producer<byte[], byte[]>> producerList; private AtomicInteger producerIndex = new AtomicInteger(0); private int timeoutMillis; private boolean enabled = true; // 默认配置问true，即打入kafka，除非有异常情况或主动设置了。 private String pattern; private AccessLogElement accessLogElement; private String localeName; private Locale locale = Locale.getDefault();
public static AccessLogElement parsePattern(String pattern) { final List<AccessLogElement> list = new ArrayList<>(); boolean replace = false; StringBuilder buf = new StringBuilder(); for (int i = 0; i < pattern.length(); ++i) { char ch = pattern.charAt(i); if (replace) { if (‘{‘ == ch) { StringBuilder name = new StringBuilder(); int j = i + 1; for (; (j < pattern.length()) && (‘}‘ != pattern.charAt(j)); ++j) { name.append(pattern.charAt(j)); } if (j + 1 < pattern.length()) { ++j; list.add(createAccessLogElement(name.toString(), pattern.charAt(j))); i = j; } else { list.add(createAccessLogElement(ch)); } } else { list.add(createAccessLogElement(ch)); } replace = false; } else if (ch == ‘%‘) { replace = true; list.add(new StringElement(buf.toString())); buf = new StringBuilder(); } else { buf.append(ch); } } if (buf.length() > 0) { list.add(new StringElement(buf.toString())); } return new AccessLogElement() { @Override protected String buildLog(Request request, Response response, long time, AccessLog accesslog) { StringBuilder sBuilder = new StringBuilder(30); for (AccessLogElement accessLogElement : list) { sBuilder.append(accessLogElement.buildLog(request, response, time, accesslog)); } return sBuilder.toString(); } }; }
<Valve className="com.letv.shop.lekafkavalve.LeKafkaAccesslogValve" enabled="true" topic="info" pattern="%{yyyy-MM-dd HH:mm:ss}t||info||AccessValve||Tomcat||%A||%a||%r||%s||%D" bootstrapServers="kafka地址" producerSize="5" properties="acks=0||producer.size=3"/>
tomcat8及以后版本的扩展要方便的多，直接继承AbstractAccessLogValve并重写log方法。
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原文地址：http://www.cnblogs.com/dimmacro/p/5566480.html
