tomcat启动失败的常见原因
根据不同情况，笔者碰到过的有以下几种情况：
1. 运行tomcat的启动文件startup.bat，弹出黑窗口，直接闪退。
这种情况一般都是没有配置JAVA_HOME导致的，配置jdk如果没有使用JAVA_HOME的方式配置环境变量，就会出这种问题
2. 启动后，停留一段时间，打印一些日志，然后窗口关闭。
这种情况一般是端口号冲突了。
由于端口号只会支持一个程序运行，如果tomcat的默认端口号被其他程序占用，就会导致冲突。解决这种问题的手段分为两种，第一，关闭占用默认端口号的程序（不太建议），第二，修改tomcat使用的默认端口号。
关闭占用默认端口号的程序
如果选择结束掉占用了默认端口号的程序，如何查看是哪个程序占用了端口号呢？
在cmd命令输入netstat -aov
本地地址最右侧就是已经被使用的端口号，找到默认端口号8080，记下最右侧的数字（PID的值）
接着打开任务管理器，找到和PID值匹配的进程，将其关闭即可（默认情况下，任务管理器不会显示PID，需要手动开启PID显示）
修改tomcat使用的默认端口号
在TomCat文件目录下找到conf文件下的server.xml文件
修改上图的8080即可。
3. 运行tomcat后，tomcat很快就启动完成了，但是日志打印了一大堆严重。
这种情况，似乎是因为tomcat的权限不足导致的，需要提升tomcat的权限，只需要修改tomcat中的config文件夹的权限，将权限改成完全控制，如下图（要注意，一定要修改电脑当前登录用户下的权限，否则没用，在下图中的组或用户名中找到当前登录的用户。）
发一下，这种情况报的错误信息。
信息: Loaded APR based Apache Tomcat Native library 1.1.14.
2009-5-25 7:55:48 org.apache.catalina.core.AprLifecycleListener init
信息: APR capabilities: IPv6 [false], sendfile [true], accept filters [false], random [true].
2009-5-25 7:55:50 org.apache.coyote.http11.Http11AprProtocol init
信息: Initializing Coyote HTTP/1.1 on http-8080
2009-5-25 7:55:50 org.apache.coyote.ajp.AjpAprProtocol init
信息: Initializing Coyote AJP/1.3 on ajp-8009
2009-5-25 7:55:50 org.apache.catalina.startup.Catalina load
信息: Initialization processed in 3594 ms
2009-5-25 7:55:50 org.apache.naming.NamingContext lookup
警告: Unexpected exception resolving reference
java.io.IOException: Cannot rename original file to C:/Program Files/Apache Software Foundation/Tomcat 6.0/conf/tomcat-users.xml.old
at org.apache.catalina.users.MemoryUserDatabase.save(MemoryUserDatabase.java:582)
at org.apache.catalina.users.MemoryUserDatabaseFactory.getObjectInstance(MemoryUserDatabaseFactory.java:104)
at org.apache.naming.factory.ResourceFactory.getObjectInstance(ResourceFactory.java:140)
at javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:304)
at org.apache.naming.NamingContext.lookup(NamingContext.java:793)
at org.apache.naming.NamingContext.lookup(NamingContext.java:140)
at org.apache.naming.NamingContextBindingsEnumeration.nextElementInternal(NamingContextBindingsEnumeration.java:113)
at org.apache.naming.NamingContextBindingsEnumeration.next(NamingContextBindingsEnumeration.java:71)
at org.apache.catalina.mbeans.GlobalResourcesLifecycleListener.createMBeans(GlobalResourcesLifecycleListener.java:137)
at org.apache.catalina.mbeans.GlobalResourcesLifecycleListener.createMBeans(GlobalResourcesLifecycleListener.java:109)
at org.apache.catalina.mbeans.GlobalResourcesLifecycleListener.lifecycleEvent(GlobalResourcesLifecycleListener.java:81)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:703)
at org.apache.catalina.startup.Catalina.start(Catalina.java:578)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
2009-5-25 7:55:50 org.apache.catalina.mbeans.GlobalResourcesLifecycleListener createMBeans
严重: Exception processing Global JNDI Resources
javax.naming.NamingException: Cannot rename original file to C:/Program Files/Apache Software Foundation/Tomcat 6.0/conf/tomcat-users.xml.old
at org.apache.naming.NamingContext.lookup(NamingContext.java:805)
at org.apache.naming.NamingContext.lookup(NamingContext.java:140)
at org.apache.naming.NamingContextBindingsEnumeration.nextElementInternal(NamingContextBindingsEnumeration.java:113)
at org.apache.naming.NamingContextBindingsEnumeration.next(NamingContextBindingsEnumeration.java:71)
at org.apache.catalina.mbeans.GlobalResourcesLifecycleListener.createMBeans(GlobalResourcesLifecycleListener.java:137)
at org.apache.catalina.mbeans.GlobalResourcesLifecycleListener.createMBeans(GlobalResourcesLifecycleListener.java:109)
at org.apache.catalina.mbeans.GlobalResourcesLifecycleListener.lifecycleEvent(GlobalResourcesLifecycleListener.java:81)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:703)
at org.apache.catalina.startup.Catalina.start(Catalina.java:578)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
2009-5-25 7:55:50 org.apache.catalina.core.StandardService start
信息: Starting service Catalina
2009-5-25 7:55:50 org.apache.catalina.core.StandardEngine start
信息: Starting Servlet Engine: Apache Tomcat/6.0.18
2009-5-25 7:55:50 org.apache.naming.NamingContext lookup
警告: Unexpected exception resolving reference
java.io.IOException: Cannot rename original file to C:/Program Files/Apache Software Foundation/Tomcat 6.0/conf/tomcat-users.xml.old
at org.apache.catalina.users.MemoryUserDatabase.save(MemoryUserDatabase.java:582)
at org.apache.catalina.users.MemoryUserDatabaseFactory.getObjectInstance(MemoryUserDatabaseFactory.java:104)
at org.apache.naming.factory.ResourceFactory.getObjectInstance(ResourceFactory.java:140)
at javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:304)
at org.apache.naming.NamingContext.lookup(NamingContext.java:793)
at org.apache.naming.NamingContext.lookup(NamingContext.java:153)
at org.apache.catalina.realm.UserDatabaseRealm.start(UserDatabaseRealm.java:253)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1037)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
at org.apache.catalina.core.StandardService.start(StandardService.java:516)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
at org.apache.catalina.startup.Catalina.start(Catalina.java:578)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
2009-5-25 7:55:50 org.apache.catalina.realm.UserDatabaseRealm start
严重: Exception looking up UserDatabase under key UserDatabase
javax.naming.NamingException: Cannot rename original file to C:/Program Files/Apache Software Foundation/Tomcat 6.0/conf/tomcat-users.xml.old
at org.apache.naming.NamingContext.lookup(NamingContext.java:805)
at org.apache.naming.NamingContext.lookup(NamingContext.java:153)
at org.apache.catalina.realm.UserDatabaseRealm.start(UserDatabaseRealm.java:253)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1037)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
at org.apache.catalina.core.StandardService.start(StandardService.java:516)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
at org.apache.catalina.startup.Catalina.start(Catalina.java:578)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
2009-5-25 7:55:50 org.apache.catalina.startup.Catalina start
严重: Catalina.start:
LifecycleException: No UserDatabase component found under key UserDatabase
at org.apache.catalina.realm.UserDatabaseRealm.start(UserDatabaseRealm.java:261)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1037)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
at org.apache.catalina.core.StandardService.start(StandardService.java:516)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
at org.apache.catalina.startup.Catalina.start(Catalina.java:578)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
2009-5-25 7:55:50 org.apache.catalina.startup.Catalina start
信息: Server startup in 299 ms