从Java中的XML文件中删除元素

Question

I have generated an xml file from an excel data base and it contains automatically an element called " offset ". To make my new file match my needs, I want to remove this element using java. here is the xml content:

<Root><models><id>2</id><modelName>Baseline</modelName><domain_id>2</domain_id><description> desctiption </description><years><Y2013>value1</Y2013><Y2014>value2</Y2014><Y2015>value3</Y2015><Y2016>value4</Y2016><Y2017>value5</Y2017></years><offset/></models></Root>

I made a code that reads(with a buffered reader) and writes the content in a new file and used the condition if:

        while (fileContent !=null){
        fileContent=xmlReader.readLine();
        if (!(fileContent.equals("<offset/>"))){
            System.out.println("here is the line:"+ fileContent);
            XMLFile+=fileContent;
            }


    }

But it does not work

Answer 1

I would personally recommend using a proper XML parser like Java DOM to check and delete your nodes, rather than dealing with your XML as raw String s (yuck). Try something like this to remove your 'offset' node.

File xmlFile = new File("your_xml.xml");
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(xmlFile);

NodeList nList = doc.getElementsByTagName("offset");
for (int i = 0; i < nList.getLength(); i++) {
    Node node = nList.item(i);
    node.getParentNode().removeChild(node); 
}

The above code removes any 'offset' nodes in an xml file.

If resources/speed considerations are an issue (like when your_xml.xml is huge), you would be better off using SAX , which is faster (a little more code intensive) and doesn't store the XML in memory.

Once your Document has been edited you'll probably want to convert it to a String to parse to your OutputStream of choice.

Hope this helps.

Answer 2

Just try to replace the unwanted string with an empty string. It is quick... and seriously dirty. But might solve your problem quickly... just to reappear later on ;-)

fileContent.replace(" <offset/> , "");

Answer 3

   String sXML= "<Root><models><id>2</id><modelName>Baseline</modelName><domain_id>2</domain_id><description> desctiption </description><years><Y2013>value1</Y2013><Y2014>value2</Y2014><Y2015>value3</Y2015><Y2016>value4</Y2016><Y2017>value5</Y2017></years><offset/></models></Root>";
   System.out.println(sXML);
   String sNewXML = sXML.replace("<offset/>", "");
   System.out.println(sNewXML);

Answer 4

String xml = "<Root><models><id>2</id><modelName>Baseline</modelName><domain_id>2</domain_id><description> desctiption </description><years><Y2013>value1</Y2013><Y2014>value2</Y2014><Y2015>value3</Y2015><Y2016>value4</Y2016><Y2017>value5</Y2017></years><offset/></models></Root>";
            xml = xml.replaceAll("<offset/>", "");
            System.out.println(xml);

Answer 5

In your original code that you included you have:

while (fileContent !=null)

Are you initializing fileContent to some non-null value before that line? If not, the code inside your while block will not run.

But I do agree with the other posters that a simple replaceAll() would be more concise, and a real XML API is better if you want to do anything more sophisticated.