java - 在 java 中读取和获取 xml 值

Question

我的列数据是采用 Base64 加密的 XML 格式。我通过使用 java 获得了值，但是所有的值都得到了，我只想要特定的值

<?xml version="1.0" encoding="UTF-8"?>
<event id="370e7324-3-85ec-63dac16aacb6">
<properties>
<property enc="BASE64" name="state" value="Hrthyw35WmnmewqzRlYXI="/>
<property enc="BASE64" name="record" value="mjhm65WmnmewqzRlYXI="/>    
<property enc="BASE64" name="application" value="Q2FsZWmnmewqzRlYXI="/>
</properties>
</event>

我的java代码是

try {
Query q="select xml from empdata";
String xml = result.getString(1);
System.out.println("----xml----"+xml);
sqlService.dbRead(connection,sql.toString(),new SqlReader() 
{
    @Override       
    public Object readRecord(ResultSet result)
        {
            try {                           
                    String xml = result.getString(1);

                        // read the xml
                        InputSource is = new InputSource();
                        is.setCharacterStream(new StringReader(xml));
                        DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
                        DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
                        Document doc = dBuilder.parse(is);
                        doc.getDocumentElement().normalize();
                        NodeList nList = doc.getElementsByTagName("property");
                        String name = null;
                        String value = null;
                        for (int temp = 0; temp < nList.getLength(); temp++) {
                            Node node = nList.item(temp);
                            Element element=null;
                            if (node.getNodeType() == Node.ELEMENT_NODE) {
                                element = (Element) node;
                                 name= element.getAttribute("name");
                                 value =  element.getAttribute("value");
                                System.out.println("--value--"+value+"----name----"+name);
                             }
                        }
                } catch (SQLException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            return null;
        }
});
}catch (SQLException e) {
  e.printStackTrace();
}

我得到了三个名称和三个值，但我只想要第三个名称和值。

Answer 1

假设您想要一个名称为“应用程序”的应用程序..

您还可以简化代码，无需检查节点的类型，getElementsByTagName 只会返回元素类型的节点。

例子

String xml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" + "<event id=\"370e7324-3-85ec-63dac16aacb6\">\n"
        + "<properties>\n" + "<property enc=\"BASE64\" name=\"state\" value=\"Hrthyw35WmnmewqzRlYXI=\"/>\n"
        + "<property enc=\"BASE64\" name=\"record\" value=\"mjhm65WmnmewqzRlYXI=\"/>\n"
        + "<property enc=\"BASE64\" name=\"application\" value=\"Q2FsZWmnmewqzRlYXI=\"/>\n" + "</properties>\n"
        + "</event>\n";

DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(new InputSource(new StringReader(xml)));
doc.getDocumentElement().normalize();
NodeList properties = doc.getElementsByTagName("property");

for (int index = 0; index < properties.getLength(); index++) {
    Node node = properties.item(index);
    Element element = (Element) node;
    if ("application".equals(element.getAttribute("name"))) {
        String name = element.getAttribute("name");
        String valueEncoded = element.getAttribute("value");
        String decoded = new String(Base64.getDecoder().decode(valueEncoded));
        System.out.println("--value--" + decoded);
    }
}

作为编写自己的过滤逻辑的替代方法，您可以使用 XPath 来表示，一种具有 native Java 支持的 XML 选择语言。

XPath xPath = XPathFactory.newInstance().newXPath();
Element element = (Element) xPath.compile("//property[@name=\"application\"]").evaluate(doc, XPathConstants.NODE);
String value = element.getAttribute("value");