tomcat 6.029启动时 严重: Exception looking up UserDatabase under key UserDatabase

tomcat在启动时报如下错误:

严重: Exception looking up UserDatabase under key UserDatabase
javax.naming.NameNotFoundException: Name UserDatabase is not bound in this Context
??????? at org.apache.naming.NamingContext.lookup(NamingContext.java:770)
??????? 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:445)
??????? at org.apache.catalina.core.StandardService.start(StandardService.java:519)
??????? at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
??????? at org.apache.catalina.startup.Catalina.start(Catalina.java:581)
??????? 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:597)
??????? at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
??????? at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
2011-12-9 14:31:20 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:445)
??????? at org.apache.catalina.core.StandardService.start(StandardService.java:519)
?2011-12-9 14:31:20 org.apache.catalina.startup.Catalina start
信息: Server startup in 20 ms

?

原因是因为在tomcat的conf/server.xml配置文件中不小心注释了一段resource配置:

不能把?注释下面这段..

<Resource
????????????? name="UserDatabase" auth="Container"
????????????? type="org.apache.catalina.UserDatabase"
????????????? description="User database that can be updated and saved"
????????????? factory="org.apache.catalina.users.MemoryUserDatabaseFactory"
????????????? pathname="conf/tomcat-users.xml" />?

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