tom启动报错：org.xml.sax.SAXParseException: Content is not allowed in prolog.

警告: Catalina.start using conf/server.xml:

org.xml.sax.SAXParseException: Content is not allowed in prolog.

        at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1231)

        at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:522)

        at org.apache.tomcat.util.digester.Digester.parse(Digester.java:1642)

        at org.apache.catalina.startup.Catalina.load(Catalina.java:524)

        at org.apache.catalina.startup.Catalina.start(Catalina.java:582)

        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)

2015-8-7 13:03:35 org.apache.catalina.startup.Catalina start

严重: Cannot start server. Server instance is not configured.

曾遇错误原因：conf/server.xml 配置文件左上角多出了一个无用的日期，是在编辑文档时，不小心弄上去的。