如何使用Java从xml文件读取十六进制值

Question

i am trying to fetch data from xml file using java.

using mysqldump the database table is converted to xml.

table contains one field which is in BLOB type.

Table structure :

CREATE TABLE `test` (
  `image` BLOB
) ENGINE=INNODB DEFAULT CHARSET=utf8

Back up data with hexadecimal value using following procedure

mysqldump -uuser -ppassword test test --compact --no-create-info --hex-blob > check.sql --xml

in xml blob field content is in hexadecimal values.

Java code that i tried is

public static void main(String args[]) {
    try {

        File fXmlFile = new File("E:\\check.sql");
        DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
        DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
        Document doc = dBuilder.parse(fXmlFile);
        doc.getDocumentElement().normalize();

        System.out.println("Root element :" + doc.getDocumentElement().getNodeName());
        NodeList nList = doc.getElementsByTagName("row");
        System.out.println("-----------------------");

        for (int temp = 0; temp < nList.getLength(); temp++) {

            Node nNode = nList.item(temp);
            if (nNode.getNodeType() == Node.ELEMENT_NODE) {

                Element eElement = (Element) nNode;

                System.out.println(" Image " + getTagValueUsingAttributeName("field","image", eElement));
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}


private static String getTagValueUsingAttributeName(String sTag, String attributeName, Element eElement){
    String value="";
    for(int i=0;i<eElement.getElementsByTagName(sTag).getLength();i++){            
        if((eElement.getElementsByTagName(sTag).item(i).getAttributes().getNamedItem("name").getTextContent()).equalsIgnoreCase(attributeName)){
            System.out.println(" - "+eElement.getElementsByTagName(sTag).item(i).getAttributes().getNamedItem("name").getTextContent());
            NodeList nlList = eElement.getElementsByTagName(sTag).item(i).getChildNodes();
            System.out.println(1);
            Node nValue = (Node) nlList.item(0);
            if(nValue!=null)
                System.out.println(2+" - "+(nValue.getNodeType() == Node.TEXT_NODE));
            value = (nValue==null)?" ":nValue.getTextContent();
            break;
        }
    }
    return value;
}

But i can not read the xml file for parsing.

Note : I tried to put the xml file in stackoverflow but it does not allow me to add xml content.

please help me.

Answer 1

If you need to decode long value encoded as Hex you could use this class: http://commons.apache.org/codec/apidocs/org/apache/commons/codec/binary/Hex.html

For example, if you have your value stored in char[] array you may use Hex.decodeHex(char[] data) to convert it into raw byte[] array. I'm assuming that you you're treating your BLOB as binary content.