如果有许多同名的父节点，如何从xml的父节点中选择所有子节点？

Question

 <?xml version="1.0" encoding="UTF-8"?> <invoice> <obs> <ob> <code>ABC</code> </ob> <ob> <code>123</code> </ob> </obs> </invoice> <invoice> <obs> <ob> <code>DEF</code> </ob> </obs> </invoice> </invoices> 

Question: I have that xml, which will come to me from external system ,it can have large number of invoice nodes and one invoice node can have large number of 'code' nodes. I want to read the code nodes of all 'invoice' nodes and save them in an array like this :

invoice[1].code[1]=ABC 
invoice[1].code[2]=123 
invoice[2].code[1]=DEF

How to do this using XPathExpression in JAVA. My code is below which is not working.

expr = xpath.compile("//invoices/invoice/obs/ob/code/text()");

 result1=expr.evaluate(dc, XPathConstants.NODESET);

nodes =(NodeList)result1;

Please give some general solution in case of number of nodes are high.

Answer 1

It will give both as there are two invoices try to give id to your xml like

 <invoices> <invoice name="invoice1"> <obs> <ob> <code>ABC</code> </ob> </obs> </invoice> <invoice name="invoice2"> <obs> <ob> <code>DEF</code> </ob> </obs> </invoice> </invoices> 

then

 expr = xpath.compile("//invoices[@name='invoice1']/invoice/obs/ob/code/text()"); 

Answer 2

There are 2 nodes where your xpath passes. You can try this.

    String xml = "<invoices><invoice><obs><ob><code>ABC</code></ob><ob><code>111</code></ob></obs></invoice><invoice><obs><ob><code>DEF</code></ob></obs></invoice></invoices>";
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder =factory.newDocumentBuilder();
    Document document  = builder.parse(new InputSource(new StringReader(xml)));
    XPathFactory xpathFactory = XPathFactory.newInstance();

    Map<String,List<String>> invoiceCodeMap = new LinkedHashMap<>();
    XPathExpression invoiceXpathExp = xpathFactory.newXPath().compile("//invoices/invoice");
    NodeList invoiceNodes = (NodeList) invoiceXpathExp.evaluate(document, XPathConstants.NODESET);
    //Iterate Invoice nodes
    for(int invoiceIndex=0;invoiceIndex<invoiceNodes.getLength();invoiceIndex++){
        String invoiceID = "invoice"+(invoiceIndex+1);
        List<String> codeList = new ArrayList<>();
        XPathExpression codeXpathExp = xpathFactory.newXPath().compile("obs/ob/code/text()");
        NodeList codeNodes = (NodeList) codeXpathExp.evaluate(invoiceNodes.item(invoiceIndex), XPathConstants.NODESET);
        for(int codeIndex=0;codeIndex<codeNodes.getLength();codeIndex++){
            Node code = codeNodes.item(codeIndex);
            codeList.add(code.getTextContent());
        }
        invoiceCodeMap.put(invoiceID, codeList);
    }
    System.out.println(invoiceCodeMap);

Answer 3

您可以尝试以下xpath：

//invoices/invoice[descendant::code[.='ABC']]/obs/ob/code