Question

我想创建一个xml文件，并且已经看过这个示例（https://www.mkyong.com/java/how-to-create-xml-file-in-java-dom/），但是我想在循环方法中生成它。

<company>
    <staff id="1">
        <firstname>yong</firstname>
        <lastname>mook kim</lastname>
        <nickname>mkyong</nickname>
        <salary>100000</salary>
    </staff>
        <staff id="2">
        <firstname>hif</firstname>
        <lastname>kiuk kim</lastname>
        <nickname>gonuy</nickname>
        <salary>50000</salary>
    </staff>
</company>

但是，使用代码：

public void printXml(String firstName, String lastName, String nickname, String salary) {

  try {

    DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
    DocumentBuilder docBuilder = docFactory.newDocumentBuilder();

    // root elements
    Document doc = docBuilder.newDocument();
    Element rootElement = doc.createElement("company");
    doc.appendChild(rootElement);

    // staff elements
    Element staff = doc.createElement("Staff");
    rootElement.appendChild(staff);

    // set attribute to staff element
    Attr attr = doc.createAttribute("id");
    attr.setValue("1");
    staff.setAttributeNode(attr);

    // shorten way
    // staff.setAttribute("id", "1");

    // firstname elements
    Element firstnameElement = doc.createElement("firstname");
    firstnameElement.appendChild(doc.createTextNode(firstName));
    staff.appendChild(firstnameElement);

    // lastname elements
    Element lastnameElement = doc.createElement("lastname");
    lastnameElement.appendChild(doc.createTextNode(lastName));
    staff.appendChild(lastnameElement);

    // nickname elements
    Element nicknameElement = doc.createElement("nickname");
    nicknameElement.appendChild(doc.createTextNode(nickname));
    staff.appendChild(nicknameElement);

    // salary elements
    Element salaryElement = doc.createElement("salary");
    salaryElement.appendChild(doc.createTextNode(salary));
    staff.appendChild(salaryElement);

    // write the content into xml file
    TransformerFactory transformerFactory = TransformerFactory.newInstance();
    Transformer transformer = transformerFactory.newTransformer();
    DOMSource source = new DOMSource(doc);
    StreamResult result = new StreamResult(new File("C:\\file.xml"));

    // Output to console for testing
    // StreamResult result = new StreamResult(System.out);

    transformer.transform(source, result);

    System.out.println("File saved!");

  } catch (ParserConfigurationException pce) {
    pce.printStackTrace();
  } catch (TransformerException tfe) {
    tfe.printStackTrace();
  }
}

}

有关公司员工的循环信息总是被替换，并且仅保存最后的信息：

for (Staff staff: staffList){
String firstName = staff.getFirstName();
String lastName = staff.getLastName();
String nickname = staff.getNickname ();
double salary = staff.getSalary();

printXml(firstName, lastName, nickname, salary);

<company>
        <staff id="2">
        <firstname>hif</firstname>
        <lastname>kiuk kim</lastname>
        <nickname>gonuy</nickname>
        <salary>50000</salary>
    </staff>
</company>

如何保存循环中得到的所有信息？谢谢。

Answer 1

您会覆盖文件，而不是附加到文件中。

您应该使用可以写入文件或追加到文件的流来初始化StreamResult。例如，您可以使用FileOutputStream，并将true传递为其构造函数以进行追加。

但是，您需要close流，因此一种选择是更改代码，以使printXml变成getXml，然后您的代码如下所示：

FileOutputStream stream = new FileOutputStream("C:\\file.xml", true);
StreamResult result = new StreamResult(stream);
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
for (Staff staff: staffList){
   DOMSource source = getXml(staff);       // call staff's getters inside getXml
   transformer.transform(source, result);
}
stream.close();

（您还应该将上面的3-4行移动到名为getTransformer的方法上。）

如何将xml文件生成为循环方法？

1 个答案: