SAXParseException: Content is not allowed in prolog

问题

I need to add the following file to my Tomcat's '/conf' directory:

<?xml version="1.0" encoding="UTF-8"?>
<Context useHttpOnly="false" path="/bbc">
    <Realm className="com.bbc.tomcat.BBCSecurityRealm"/>
</Context>

After adding this file, I get the following error when Tomcat starts up"

ERROR ecmdefault util.digester.Digester 18:37:14,477 localhost-startStop-1 : 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 com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:195)
    at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.fatalError(ErrorHandlerWrapper.java:174)
    at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:388)
    at com.sun.org.apache.xerces.internal.impl.XMLScanner.reportFatalError(XMLScanner.java:1427)

回答1:

Your xml file has some invisible chars (most likely the BOM) at the start (before <?xml version="1.0" encoding="UTF-8"?>) which is not allowed in xml. you could view it using a hex editor. Simplest way to fix it is to create an empty text file and copy the content into it, change the extension to xml.

Check this answer for further help.

From http://www.rgagnon.com/javadetails/java-handle-utf8-file-with-bom.html

UTF8 file are a special case because it is not recommended to add a BOM to them because it can break other tools like Java. In fact, Java assumes the UTF8 don't have a BOM so if the BOM is present it won't be discarded and it will be seen as data.

回答2:

I had a similar issue but this reference link provided the solution spot on.

Quote from the article.

Any characters before the start of the XML content will cause above error.

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

来源：https://stackoverflow.com/questions/20551572/saxparseexception-content-is-not-allowed-in-prolog