An error occurs during webwork verification. The message "content is not allowed in Prolog" is displayed. If an error occurs while parsing the XML file, find the corresponding file, I found that I forgot to comment out several lines of Chinese characters at the beginning. I commented out them and the problem was solved. Because I had not encountered such a problem before, I found the following information on the Internet:
Dom4j may encounter an error when reading the XML file: content is not allowed in Prolog exception cause
The XML is UTF-8 encoded. If the file is edited through ultraedit, it will be added to the UTF-8 file without BOM header, but dom4j does not recognize this BOM (dom4j1.3 ), solution: Upgrade dom4j to 1.6 to solve www.dom4j.org.
What is Bom? Http://www.unicode.org/faq/utf_bom.html#22
The Unicode specification has the concept of BOM. Bom -- byte order mark, which is a mark of the byte order. Here is a description of BOM:
There is a character named "Zero Width no-break space" in the UCS encoding, and its encoding is feff. Fffe does not exist in the UCs, so it should not appear in actual transmission. We recommend that you transmit the character "Zero Width no-break space" before transmitting the byte stream in the UCS specification ". In this way, if the receiver receives feff, it indicates that the byte stream is big-Endian; if it receives fffe, it indicates that the byte stream is little-Endian. Therefore, the character "Zero Width no-break space" is also called Bom.
The UTF-8 does not need BOM to indicate the byte order, but BOM can be used to indicate the encoding method. The UTF-8 code for the character "Zero Width no-break space" is ef bb bf. So if the receiver receives a byte stream starting with ef bb bf, it will know that this is UTF-8 encoding.
Windows uses BOM to mark the encoding of text files.
In addition, the Unicode website FAQ-BOM detailed Bom. The official natural authority is only in English, and it looks hard
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I saw an article about using ant to build a Java project in eclipse. I created a project according to the instructions in the article, and created several folders including classes, DIST, Doc, Lib, and build. XML file. Build. the content of the XML file is also directly copied. Because the content is directly copied from the web page, "<" ">" is in Chinese format, So I replaced it.
However, if the project is selected, select "project", "properties", "builders", "New ...", When "ant build" is selected: the error "content is not allowed in Prolog" is returned when "Bucket file" is loaded.
I went to Google and circled it. I also learned something about it. I read a small article and thought it may be a build. xml file format error.
When using ultraedit to compile a hibernate ing file, it is found that ultraedit automatically adds a special character to the beginning of the UTF-8 encoded file. This is invisible in ultraedit and can be seen in other editors. Content is not allowed in Prolog error occurs when dom4j is used to parse the file. Use another editor to remove the character and correct the error.
You should change to an XML parser. UTF-8 file headers are Unicode-standard and have been mentioned in the XML standard. Some XML parsers written in Java are poor and do not know such a file header. But all the better Resolvers know each other. For example, Apache parser.
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