从Java中选定的XML元素获取子元素及其值

Question

Bit of background:

saveFilePath is a location already selected by a user via a JFileChooser

selectedElement is a String which is the value selected from a comboBox

NodeList selectedElementList = doc.getElementsByTagName(selectedElement); returns all of the elements that are found in the XML file that match the element selected from the comboBox.

What I'm trying to do is to get all child elements from the selected element, eg get elements A & B

<selectedElement>
    <a> AA </a>
    <b> BB </b>
</selectedElement>
<selectedElement>
    <a> AB </a>
    <b> BC </b>
</selectedElement>

Then find all instances of the selectedElement and all the child elements associated with it to print out to a file. NOTE that selectedElement is more than likely going to be a child of a child of the documents root element.

Here's what I've got so far, the fileWriter.append(a + "," + + newline); prints out all of the occurrences of the selected elements within the XML file, but I can't seem to figure out how to get it to print out the child Elements and their values.

This is what I have:

try {                   
                    // Make a file writer that uses the location entered
                    fileWriter = new FileWriter(saveFilePath);
                    fileWriter.append(selectedElement + "," + newline);

                    // For each occurance of the element
                    for (int k = 0; k < selectedElementList.getLength(); k++) {

                        // Add the value of it to the CSV file
                        String a = selectedElementList.item(k).getTextContent();
                        fileWriter.append(a + "," + newline);
//                      for (int l = 0; l < a.getLength(); l++) {
//                          
//                          
//                          String item = element.getNodeName().toString();
//                          String item2 = element.getNodeValue();
//                          
//                          System.out.println("The node name is: " + item + newline);
//                          System.out.println("The node VALUE is: " + item2 + newline);
//                      }                                           

                    }

                    // Close the fileWriter stream
                    fileWriter.flush();
                    fileWriter.close();

                    // Disable the create button and enable the open button
                    createButton.setEnabled(false);
                    openButton.setEnabled(true);

                } catch (IOException e) {
                    e.printStackTrace();
                }

Maybe I need to create a second document that contains only the required XML? or maybe getElementsByTagName isn't the right method to be using? I basicalla want to get the child nodes of the selected element!

Any help would be appreciated

I'd post the whole thing on here but it's 320 lines long and this is just one of the many parts of my little application :)

Answer 1

I think I have a solution using something called "dynamic data projection " (Disclosure: I'm affiliated with that project). But I changed your XML to make sense (added root element and gave the selected elements different names so I can select one of them ). Here is my XML version:

<root>
    <selectedElement>
        <a> AA </a>
        <b> BB </b>
    </selectedElement>
    <selectedElement>
        <a> AB </a>
        <b> BC </b>
    </selectedElement>
</root> 

And here is the program:

public class ExtractElement {

    public interface Projection {

        interface SelectedElement {
            @XBRead("name()")
            String getName();
            @XBRead(".")
            String getValue();
        }

        @XBRead("//{0}/*")
        List<SelectedElement> getSelectedElements(String name);
    }
    public static void main(String[] args) throws IOException {
        Projection projection = new XBProjector().io().url("resource://data.xml").read(Projection.class);        
        for (SelectedElement se:projection.getSelectedElements("selectedElement")) {
            System.out.println("Found element with name "+se.getName()+" and value "+se.getValue());
        }    
    }    
}

It prints out:

Found element with name a and value  AA 
Found element with name b and value  BB 
Found element with name a and value  AB 
Found element with name b and value  BC 

Is this what you liked to have?

Answer 2

Managed to solve this by doing the following:

// For each occurance of the element
                for (int k = 0; k < selectedElementList.getLength(); k++) {

                    // Add the value of it to the CSV file
                    String a = selectedElementList.item(k).getTextContent();
                    fileWriter.append(a + "," + newline);
                    //log.append(a + "," + newline);        


                    NodeList temp = selectedElementList.item(k).getChildNodes();
                    for(int l = 0; l < temp.getLength(); l++) {

                        Node tempNode = temp.item(l);

                        if (tempNode.hasChildNodes()) {

                            String tnodeName = tempNode.getNodeName();

                            log.append("tNodeName is: " + tnodeName.toString() + newline);
                        }
                    }               

                }