Tomcat日志目录的理解
最近，使用tomcat做服务器，实现java web程序。当然，做程序嘛，难免有错误，但是出现了错误，最大的希望就是tomcat能够告诉我，错误到底是什么？
当然了，具体的错误种类太多，常见的有语法错误，这一点还好处理；上升到逻辑错误，就难了；再一个就是，对于tomcat加载application的过程不清楚的话，也会出现不符合约定的错误啦，这个就更加难了。
还在tomcat有日志功能，在很大程度上帮助我们分析错误，定位错误。
logs目录：
- catalina.2013-07-11.log：这个日志文件就是记录，当前servlet容器中加载的各applications，就是所有在webapps目录下的子目录。当然在你开启tomcat的那个时候，catalina.xxxx-xx-xx.log会被创建。然后，记录的信息如下：
这个时候，还没有任何一个servlet被加载。但是catalina这个servlet容器正在后台加载对应的servlets。2013-7-11 8:54:23 org.apache.catalina.core.AprLifecycleListener init 信息: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: C:\Program Files\Apache Software Foundation\Tomcat 7.0\bin;C:\WINDOWS\Sun\Java\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\Program Files\Java\jdk1.6.0_10\bin; C:\CTeX\LOCALT~1\ty\bin;C:\CTeX\LOCALT~1\cct\bin;C:\CTeX\texmf\miktex\bin;C:\CTeX\gs\gs8.51\bin;C:\CTeX\WinEdt;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\Program Files\Common Files\Thunder Network\KanKan\Codecs,; d:\Program Files\Tencent\QQPCMgr\6.6.2159.401;C:\Program Files\EgisTec Port Locker\;d:\Program Files\MATLAB\R2011a\runtime\win32; d:\Program Files\MATLAB\R2011a\bin;F:\apache-ant-1.9.1\bin;d:\apache-maven-3.0.5\bin;E:\vim\GVimPortable;;. 2013-7-11 8:54:24 org.apache.coyote.AbstractProtocol init 信息: Initializing ProtocolHandler ["http-bio-8080"]
d在数分钟后，你刷新logs目录，你就能看到catalina.xxxx-xx-xx.log内容有变化。如下：
这个时候，work目录下的catalina目录下，会对应产生相应的目录，但是目录下的内容是空的。我们知道Servlet的加载有两种情况，2013-7-11 9:02:39 org.apache.coyote.AbstractProtocol init 信息: Initializing ProtocolHandler ["ajp-bio-8009"] 2013-7-11 9:02:39 org.apache.catalina.startup.Catalina load 信息: Initialization processed in 9393 ms 2013-7-11 9:02:39 org.apache.catalina.core.StandardService startInternal 信息: Starting service Catalina 2013-7-11 9:02:39 org.apache.catalina.core.StandardEngine startInternal 信息: Starting Servlet Engine: Apache Tomcat/7.0.27 2013-7-11 9:02:39 org.apache.catalina.startup.HostConfig deployDescriptor 信息: Deploying configuration descriptor C:\Program Files\Apache Software Foundation\Tomcat 7.0\conf\Catalina\localhost\DormManaSys.xml 2013-7-11 9:02:39 org.apache.catalina.loader.WebappClassLoader validateJarFile 信息: validateJarFile(E:\MDormintorySystem\DormManaSystem\WebRoot\WEB-INF\lib\servlet-api.jar) - jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class 2013-7-11 9:02:40 org.apache.catalina.startup.HostConfig deployDescriptor 信息: Deploying configuration descriptor C:\Program Files\Apache Software Foundation\Tomcat 7.0\conf\Catalina\localhost\ProjectOne.xml 2013-7-11 9:02:40 org.apache.catalina.startup.HostConfig deployDirectory 信息: Deploying web application directory C:\Program Files\Apache Software Foundation\Tomcat 7.0\webapps\bank 2013-7-11 9:02:40 org.apache.catalina.startup.HostConfig deployDirectory 信息: Deploying web application directory C:\Program Files\Apache Software Foundation\Tomcat 7.0\webapps\docs 2013-7-11 9:02:40 org.apache.catalina.startup.HostConfig deployDirectory 信息: Deploying web application directory C:\Program Files\Apache Software Foundation\Tomcat 7.0\webapps\host-manager 2013-7-11 9:02:40 org.apache.catalina.startup.HostConfig deployDirectory 信息: Deploying web application directory C:\Program Files\Apache Software Foundation\Tomcat 7.0\webapps\manager 2013-7-11 9:02:41 org.apache.catalina.startup.HostConfig deployDirectory 信息: Deploying web application directory C:\Program Files\Apache Software Foundation\Tomcat 7.0\webapps\myapp 2013-7-11 9:02:41 org.apache.catalina.startup.HostConfig deployDirectory 信息: Deploying web application directory C:\Program Files\Apache Software Foundation\Tomcat 7.0\webapps\ROOT 2013-7-11 9:02:41 org.apache.catalina.startup.HostConfig deployDirectory 信息: Deploying web application directory C:\Program Files\Apache Software Foundation\Tomcat 7.0\webapps\WebRoot 2013-7-11 9:02:41 org.apache.coyote.AbstractProtocol start 信息: Starting ProtocolHandler ["http-bio-8080"] 2013-7-11 9:02:41 org.apache.coyote.AbstractProtocol start 信息: Starting ProtocolHandler ["ajp-bio-8009"] 2013-7-11 9:02:41 org.apache.catalina.startup.Catalina start 信息: Server startup in 2047 ms
- 在application的配置文件中，配置了load-on-startup选项为1；那么，就在servlet容器启动时候，就加载。
- Servlet在第一次被请求时，由servlet容器加载。（导致"第一次惩罚”问题）
- commons-daemon.xxxx-xx-xx.log：这个log文件的具体作用，我不明白，刚启动时候的情况时：
[2013-07-11 09:09:43] [info] Commons Daemon procrun (1.0.10.0 32-bit) started [2013-07-11 09:09:43] [info] Running 'Tomcat7' Service... [2013-07-11 09:09:43] [info] Starting service... [2013-07-11 09:09:44] [info] Service started in 1109 ms. - tomcat7-stdout.xxxx-xx-xx.log：这个log的作用是，当你的xxx.class文件中，有控制台的输出信息，那么当application部署到tomcat上，有访问的时候，这些控制台信息会被写入到这个log文件中。这一点非常重要奥，因为有了这个文件，你可以更加深入的分析你的程序的执行状况。
2013-07-11 09:09:43 Commons Daemon procrun stdout initialized LogDate.txtthe water MARK file is located in C:\Program Files\Apache Software Foundation\Tomcat 7.0\webapps\ROOT\waterMark.jpg 2013-07-11 09:43:35 Commons Daemon procrun stdout initialized LogDate.txtthe water MARK file is located in C:\Program Files\Apache Software Foundation\Tomcat 7.0\webapps\ROOT\waterMark.jpg initialize the request from client attribute REPLACED(org.apache.catalina.ASYNC_SUPPORTED , true) initialize the request from client attribute REPLACED(org.apache.catalina.ASYNC_SUPPORTED , true) initialize the request from client attribute REPLACED(org.apache.catalina.ASYNC_SUPPORTED , true) initialize the request from client attribute REPLACED(org.apache.catalina.ASYNC_SUPPORTED , true) initialize the request from client attribute REPLACED(org.apache.catalina.ASYNC_SUPPORTED , true) initialize the request from client attribute REPLACED(org.apache.catalina.ASYNC_SUPPORTED , true) initialize the request from client attribute REPLACED(org.apache.catalina.ASYNC_SUPPORTED , true) initialize the request from client attribute REPLACED(org.apache.catalina.ASYNC_SUPPORTED , true) initialize the request from client attribute REPLACED(org.apache.catalina.ASYNC_SUPPORTED , true) initialize the request from client attribute REPLACED(org.apache.catalina.ASYNC_SUPPORTED , true) initialize the request from client attribute REPLACED(org.apache.catalina.ASYNC_SUPPORTED , true) initialize the request from client attribute REPLACED(org.apache.catalina.ASYNC_SUPPORTED , true) initialize the request from client attribute REPLACED(org.apache.catalina.ASYNC_SUPPORTED , true) initialize the request from client attribute REPLACED(org.apache.catalina.ASYNC_SUPPORTED , true) the original file is located in /test.jpg next will deal with image showed all files can be read!!!bla bla bla attribute ADDED(message , Cannot call sendError() after the response has been committed) attribute ADDED(e , java.lang.IllegalStateException: Cannot call sendError() after the response has been committed) attribute ADDED(javax.servlet.error.exception , java.lang.IllegalStateException: Cannot forward after response has been committed) initialize the request from client attribute REPLACED(org.apache.catalina.ASYNC_SUPPORTED , true) - localhost_access_log.xxxx-xx-xx.txt：这个log文件是记录你浏览器发送的request。所有的requests信息都会记录其中，这样就可以分析访问状况；但是呢，对于错误信息什么的不做记录！！！
127.0.0.1 - - [11/Jul/2013:09:44:24 +0800] "GET / HTTP/1.1" 200 415 127.0.0.1 - - [11/Jul/2013:09:44:24 +0800] "GET /favicon.ico HTTP/1.1" 404 988 127.0.0.1 - - [11/Jul/2013:09:49:55 +0800] "GET /choose.jsp HTTP/1.1" 200 646 127.0.0.1 - - [11/Jul/2013:09:49:55 +0800] "GET /favicon.ico HTTP/1.1" 404 988 127.0.0.1 - - [11/Jul/2013:09:49:56 +0800] "GET /favicon.ico HTTP/1.1" 404 988 127.0.0.1 - - [11/Jul/2013:09:50:05 +0800] "GET /filter_image.jsp HTTP/1.1" 200 117 127.0.0.1 - - [11/Jul/2013:09:50:05 +0800] "GET /favicon.ico HTTP/1.1" 404 988 - localhost.xxxx-xx-xx.log：这个文件是记录访问过程中发生的异常。
2013-7-11 10:06:16 org.apache.catalina.core.StandardWrapperValve invoke 严重: Servlet.service() for servlet [default] in context with path [] threw exception java.lang.IllegalStateException: Cannot forward after response has been committed at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:339) at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:329) at test.Filter_Exception.doFilter(Filter_Exception.java:41) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at test.Filter_Log.doFilter(Filter_Log.java:49) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:307) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) - host-manager.2013-07-11.log和manager.2013-07-11.log，还有tomcat7-stderr.2013-07-11.log的作用不明。望请赐教。