问题
I am getting exception while trying to parse an XML document.
I went through many post like here and here. But still my problem not got solved. I checked i dont have any spaces too in header.I created it with notepad and i choosed encoding as utf-8 while saving.
My XML file looks like this
<?xml version="1.0" encoding="UTF-8"?>
<poem>
<title>Roses are Red</title>
<l>Roses are red</l>
</poem>
I am using java to load the file and parse it. My java code is
File xml = new File("d:\\uploads\test.xml");
try{
XMLReader xr = XMLReaderFactory.createXMLReader();
MySAXApp handler = new MySAXApp();
xr.setContentHandler(handler);
xr.setErrorHandler(handler);
FileReader r = new FileReader(xml);
xr.parse(new InputSource(r));
}
catch(Exception e)
{
log.info("Exception : "+e.getMessage());
}
My MySAXApp class is below
package utility;
import java.io.FileReader;
import java.util.logging.Logger;
import org.xml.sax.XMLReader;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.helpers.XMLReaderFactory;
import org.xml.sax.helpers.DefaultHandler;
public class MySAXApp extends DefaultHandler {
public Logger log;
public MySAXApp ()
{
super();
log = Logger.getAnonymousLogger();
}
public void startDocument ()
{
log.info("Start document");
}
public void endDocument ()
{
log.info("End document");
}
public void startElement (String uri, String name,String qName, Attributes atts)
{
log.info("Start element: " + qName);
}
public void endElement (String uri, String name, String qName)
{
log.info("End element: " + qName);
}
public void characters (char ch[], int start, int length)
{
log.info("values: \"");
for (int i = start; i < start + length; i++) {
switch (ch[i]) {
case '\\':
log.info("\\\\");
break;
case '"':
log.info("\\\"");
break;
case '\n':
log.info("\\n");
break;
case '\r':
log.info("\\r");
break;
case '\t':
log.info("\\t");
break;
default:
log.info(ch[i]+"");
break;
}
}
log.info("\"\n");
}
}
Stack trace
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:1411)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:1038)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:648)
at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:140)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:807)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:107)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1205)
at utility.PerformOperation.startIndexing(PerformOperation.java:91)
at utility.Upload.doPost(Upload.java:126)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)
回答1:
This is explained by @MikeSokolov in the first of your links. Quote:
Another thing that often happens is a UTF-8 BOM (byte order mark), which is allowed before the XML declaration can be treated as whitespace if the document is handed as a stream of characters to an XML parser rather than as a stream of bytes.
FileReader reads the file as a character stream, and to read the file as a byte stream, you should use FileInputStream instead, as follows:
FileInputStream is = new FileInputStream(xml);
xr.parse(new InputSource(is));
If you examine your text file in a hex editor you will see the UTF-8 BOM at the start (EF BB BF) and it is this that is causing the problem when using FileReader.
回答2:
You can use the following method to read the XML file to a String and then parse the String. The key is specifying the encoding when reading the file.
public static void XMLtoString(File file) {
String encoding = "";
String str = "";
try {
// detect the encoding of the file
CharsetDetector cd = new CharsetDetector().setText(new BufferedInputStream(new FileInputStream(file)));
encoding = cd.detect().getName();
// to avoid the BOM ("byte order mark") being added to the String, encoding is specified as a parameter
str = FileUtils.readFileToString(file, encoding);
}
catch (IOException e) {
System.err.println("Caught IOException: " + e.getMessage());
}
}
来源：https://stackoverflow.com/questions/18655664/java-saxparserexception-content-is-not-allowed-in-prolog