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“Content is not allowed in prolog” when parsing perfectly valid XML on GAE

由 a 夏天 提交于 2019-11-26 22:17:21

The encoding in your XML and XSD (or DTD) are different.
XML file header: <?xml version='1.0' encoding='utf-8'?>
XSD file header: <?xml version='1.0' encoding='utf-16'?>

Another possible scenario that causes this is when anything comes before the XML document type declaration. i.e you might have something like this in the buffer: 

helloworld<?xml version="1.0" encoding="utf-8"?>

or even a space or special character.

There are some special characters called byte order markers that could be in the buffer. Before passing the buffer to the Parser do this... 

String xml = "<?xml ...";
xml = xml.trim().replaceFirst("^([\\W]+)<","<");

This error message is always caused by the invalid XML content in the beginning element. For example, extra small dot “.” in the beginning of XML element.

Any characters before the “<?xml….” will cause above “org.xml.sax.SAXParseException: Content is not allowed in prolog” error message.

A small dot “.” before the “<?xml….

To fix it, just delete all those weird characters before the “<?xml“.

Ref: http://www.mkyong.com/java/sax-error-content-is-not-allowed-in-prolog/

I was facing the same issue. In my case XML files were generated from c# program and feeded into AS400 for further processing. After some analysis identified that I was using UTF8 encoding while generating XML files whereas javac(in AS400) uses "UTF8 without BOM". So, had to write extra code similar to mentioned below:

//create encoding with no BOM
Encoding outputEnc = new UTF8Encoding(false); 
//open file with encoding
TextWriter file = new StreamWriter(filePath, false, outputEnc);           

file.Write(doc.InnerXml);
file.Flush();
file.Close(); // save and close it

Removing the xml declaration solved it

<?xml version='1.0' encoding='utf-8'?>

I had issue while inspecting the xml file in notepad++ and saving the file, though I had the top utf-8 xml tag as <?xml version="1.0" encoding="utf-8"?>

Got fixed by saving the file in notpad++ with Encoding(Tab) > Encode in UTF-8:selected (was Encode in UTF-8-BOM)

In my xml file, the header looked like this: 

<?xml version="1.0" encoding="utf-16"? />

In a test file, I was reading the file bytes and decoding the data as UTF-8 (not realizing the header in this file was utf-16) to create a string.

byte[] data = Files.readAllBytes(Paths.get(path));
String dataString = new String(data, "UTF-8");

When I tried to deserialize this string into an object, I was seeing the same error:

javax.xml.stream.XMLStreamException: ParseError at [row,col]:[1,1]
Message: Content is not allowed in prolog.

When I updated the second line to

String dataString = new String(data, "UTF-16");

I was able to deserialize the object just fine. So as Romain had noted above, the encodings need to match.

Ravi Kiran

I was facing the same problem called "Content is not allowed in prolog" in my xml file.

Solution

Initially my root folder was '#Filename'.

When i removed the first character '#' ,the error got resolved.

No need of removing the #filename... Try in this way..

Instead of passing a File or URL object to the unmarshaller method, use a FileInputStream.

File myFile = new File("........");
Object obj = unmarshaller.unmarshal(new FileInputStream(myFile));

I had a tab character instead of spaces. Replacing the tab '\t' fixed the problem.

Cut and paste the whole doc into an editor like Notepad++ and display all characters.

In my instance of the problem, the solution was to replace german umlauts (äöü) with their HTML-equivalents...

bellow are cause above “org.xml.sax.SAXParseException: Content is not allowed in prolog” exception.

  1. First check the file path of schema.xsd and file.xml.
  2. The encoding in your XML and XSD (or DTD) should be same.
    XML file header: <?xml version='1.0' encoding='utf-8'?>
    XSD file header: <?xml version='1.0' encoding='utf-8'?>
  3. if anything comes before the XML document type declaration.i.e: hello<?xml version='1.0' encoding='utf-16'?>

In my case, I had the problem with a build.xml file. This was solved with just going to Build > Clean Project.

In the spirit of "just delete all those weird characters before the <?xml", here's my Java code, which works well with input via a BufferedReader:

    BufferedReader test = new BufferedReader(new InputStreamReader(fisTest));
    test.mark(4);
    while (true) {
        int earlyChar = test.read();
        System.out.println(earlyChar);
        if (earlyChar == 60) {
            test.reset();
            break;
        } else {
            test.mark(4);
        }
    }

FWIW, the bytes I was seeing are (in decimal): 239, 187, 191.

Unexpected reason: # character in file path

Due to some internal bug, the error Content is not allowed in prolog also appears if the file content itself is 100% correct but you are supplying the file name like C:\Data\#22\file.xml.

This may possibly apply to other special characters, too.

How to check: If you move your file into a path without special characters and the error disappears, then it was this issue.

标签
java
xml
google-app-engine
parsing
stax
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