啟動tomcat是出現錯誤（ Parse Fatal Error at line 1 column 1: Content is not allowed in prolog.）
2010-3-8 9:38:58 org.apache.coyote.http11.Http11Protocol init
資訊: Initializing Coyote HTTP/1.1 on http-8080
2010-3-8 9:38:58 org.apache.catalina.startup.Catalina load
資訊: Initialization processed in 468 ms
2010-3-8 9:38:58 org.apache.commons.digester.Digester fatalError
嚴重: Parse Fatal Error at line 1 column 1: Content is not allowed in prolog.
org.xml.sax.SAXParseException: Content is not allowed in prolog.
at org.apache.xerces.util.ErrorHandlerWrapper.createSAXParseException(Unknown Source)
at org.apache.xerces.util.ErrorHandlerWrapper.fatalError(Unknown Source)
at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
at org.apache.xerces.impl.XMLScanner.reportFatalError(Unknown Source)
at org.apache.xerces.impl.XMLDocumentScannerImpl$PrologDispatcher.dispatch(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.apache.commons.digester.Digester.parse(Digester.java:1567)
at org.apache.catalina.users.MemoryUserDatabase.open(MemoryUserDatabase.java:370)
at org.apache.catalina.users.MemoryUserDatabaseFactory.getObjectInstance(MemoryUserDatabaseFactory.java:97)
at org.apache.naming.factory.ResourceFactory.getObjectInstance(ResourceFactory.java:129)
at javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:304)
at org.apache.naming.NamingContext.lookup(NamingContext.java:791)
at org.apache.naming.NamingContext.lookup(NamingContext.java:151)
at org.apache.catalina.mbeans.GlobalResourcesLifecycleListener.createMBeans(GlobalResourcesLifecycleListener.jav
a:155)
at org.apache.catalina.mbeans.GlobalResourcesLifecycleListener.createMBeans(GlobalResourcesLifecycleListener.jav
a:125)
at org.apache.catalina.mbeans.GlobalResourcesLifecycleListener.lifecycleEvent(GlobalResourcesLifecycleListener.j
ava:97)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:2306)
at org.apache.catalina.startup.Catalina.start(Catalina.java:556)
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:592)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:287)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:425)
2010-3-8 9:38:58 org.apache.naming.NamingContext lookup
警告: Unexpected exception resolving reference
org.xml.sax.SAXParseException: Content is not allowed in prolog.
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.apache.commons.digester.Digester.parse(Digester.java:1567)
at org.apache.catalina.users.MemoryUserDatabase.open(MemoryUserDatabase.java:370)
at org.apache.catalina.users.MemoryUserDatabaseFactory.getObjectInstance(MemoryUserDatabaseFactory.java:97)
at org.apache.naming.factory.ResourceFactory.getObjectInstance(ResourceFactory.java:129)
at javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:304)
at org.apache.naming.NamingContext.lookup(NamingContext.java:791)
at org.apache.naming.NamingContext.lookup(NamingContext.java:151)
at org.apache.catalina.mbeans.GlobalResourcesLifecycleListener.createMBeans(GlobalResourcesLifecycleListener.jav
a:155)
at org.apache.catalina.mbeans.GlobalResourcesLifecycleListener.createMBeans(GlobalResourcesLifecycleListener.jav
a:125)
at org.apache.catalina.mbeans.GlobalResourcesLifecycleListener.lifecycleEvent(GlobalResourcesLifecycleListener.j
ava:97)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:2306)
at org.apache.catalina.startup.Catalina.start(Catalina.java:556)
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:592)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:287)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:425)
2010-3-8 9:38:58 org.apache.catalina.mbeans.GlobalResourcesLifecycleListener createMBeans
嚴重: Exception processing Global JNDI Resources
javax.naming.NamingException: Content is not allowed in prolog.
at org.apache.naming.NamingContext.lookup(NamingContext.java:803)
at org.apache.naming.NamingContext.lookup(NamingContext.java:151)
at org.apache.catalina.mbeans.GlobalResourcesLifecycleListener.createMBeans(GlobalResourcesLifecycleListener.jav
a:155)
at org.apache.catalina.mbeans.GlobalResourcesLifecycleListener.createMBeans(GlobalResourcesLifecycleListener.jav
a:125)
at org.apache.catalina.mbeans.GlobalResourcesLifecycleListener.lifecycleEvent(GlobalResourcesLifecycleListener.j
ava:97)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:2306)
at org.apache.catalina.startup.Catalina.start(Catalina.java:556)
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:592)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:287)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:425)
2010-3-8 9:38:58 org.apache.catalina.core.StandardService start
資訊: Starting service Catalina
2010-3-8 9:38:58 org.apache.catalina.core.StandardEngine start
資訊: Starting Servlet Engine: Apache Tomcat/5.0.28
2010-3-8 9:38:58 org.apache.commons.digester.Digester fatalError
嚴重: Parse Fatal Error at line 1 column 1: Content is not allowed in prolog.
org.xml.sax.SAXParseException: Content is not allowed in prolog.
at org.apache.xerces.util.ErrorHandlerWrapper.createSAXParseException(Unknown Source)
at org.apache.xerces.util.ErrorHandlerWrapper.fatalError(Unknown Source)
at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
at org.apache.xerces.impl.XMLScanner.reportFatalError(Unknown Source)
at org.apache.xerces.impl.XMLDocumentScannerImpl$PrologDispatcher.dispatch(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.apache.commons.digester.Digester.parse(Digester.java:1567)
at org.apache.catalina.users.MemoryUserDatabase.open(MemoryUserDatabase.java:370)
at org.apache.catalina.users.MemoryUserDatabaseFactory.getObjectInstance(MemoryUserDatabaseFactory.java:97)
at org.apache.naming.factory.ResourceFactory.getObjectInstance(ResourceFactory.java:129)
at javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:304)
at org.apache.naming.NamingContext.lookup(NamingContext.java:791)
at org.apache.naming.NamingContext.lookup(NamingContext.java:151)
at org.apache.catalina.realm.UserDatabaseRealm.start(UserDatabaseRealm.java:252)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1075)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:478)
at org.apache.catalina.core.StandardService.start(StandardService.java:480)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:2313)
at org.apache.catalina.startup.Catalina.start(Catalina.java:556)
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:592)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:287)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:425)
2010-3-8 9:38:58 org.apache.naming.NamingContext lookup
警告: Unexpected exception resolving reference
org.xml.sax.SAXParseException: Content is not allowed in prolog.
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.apache.commons.digester.Digester.parse(Digester.java:1567)
at org.apache.catalina.users.MemoryUserDatabase.open(MemoryUserDatabase.java:370)
at org.apache.catalina.users.MemoryUserDatabaseFactory.getObjectInstance(MemoryUserDatabaseFactory.java:97)
at org.apache.naming.factory.ResourceFactory.getObjectInstance(ResourceFactory.java:129)
at javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:304)
at org.apache.naming.NamingContext.lookup(NamingContext.java:791)
at org.apache.naming.NamingContext.lookup(NamingContext.java:151)
at org.apache.catalina.realm.UserDatabaseRealm.start(UserDatabaseRealm.java:252)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1075)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:478)
at org.apache.catalina.core.StandardService.start(StandardService.java:480)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:2313)
at org.apache.catalina.startup.Catalina.start(Catalina.java:556)
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:592)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:287)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:425)
javax.naming.NamingException: Content is not allowed in prolog.
at org.apache.naming.NamingContext.lookup(NamingContext.java:803)
at org.apache.naming.NamingContext.lookup(NamingContext.java:151)
at org.apache.catalina.realm.UserDatabaseRealm.start(UserDatabaseRealm.java:252)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1075)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:478)
at org.apache.catalina.core.StandardService.start(StandardService.java:480)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:2313)
at org.apache.catalina.startup.Catalina.start(Catalina.java:556)
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:592)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:287)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:425)
2010-3-8 9:38:58 org.apache.catalina.startup.Catalina start
嚴重: Catalina.start:
LifecycleException: No UserDatabase component found under key UserDatabase
at org.apache.catalina.realm.UserDatabaseRealm.start(UserDatabaseRealm.java:259)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1075)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:478)
at org.apache.catalina.core.StandardService.start(StandardService.java:480)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:2313)
at org.apache.catalina.startup.Catalina.start(Catalina.java:556)
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:592)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:287)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:425)
2010-3-8 9:38:58 org.apache.catalina.startup.Catalina start
資訊: Server startup in 78 ms
問題解決過程及原因分析：
以"No UserDatabase component found under key UserDatabase"為關鍵字搜尋，看了幾篇文章說的產生的情況各不相同，檢視tomcat的server.xml檔案沒有異常，所以備份server.xml檔案後，以server-minimal.xml檔案作為server.xml檔案啟動也還是有錯誤，這時看到conf目錄下還有個tomcat-users.xml檔案，用emeditor開啟時出現"Null character(00H) contained in the file will be replaced with spaces."的message box，才知道是這個檔案出了問題。
找到之前安裝的tomcat(版本相同)的備份目錄，copy了一個tomcat-users.xml檔案，再啟動tomcat就正常了，把備份的server.xml檔案改回來後，啟動也正常了。
看了那個損壞了的tomcat-users.xml檔案的修改時間才發現這個檔案就在剛剛之前被修改過了，而剛剛之前我重啟了電腦，重啟的時候等了半天win7還是在關機中，所以我就按就電源天關n秒強制關機了，估計就是因為這個，才造成的檔案損壞。
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原先百度一直說是web.xml檔案有編碼錯誤，浪費我好長時間也沒弄好，終於看到這篇文章，算是救了我啊！！再次感謝啦
我用的是MyEcplise自帶的tomcat，後來就找了tomcat6.x的/conf下的tomcat-users.xml複製到自帶tomcat的/conf下，重啟就好了