Question

正在研究一个简单的XML Web服务，它允许您对XML文件执行简单的CRUD操作。这是我的客户代码：

@WebMethod(operationName = "Delete")
public boolean Delete(String std_id) throws Exception {
    File file = new File("C:/Users/user/Desktop/myStudentInstance/myStudentInstance.xml");
    boolean isDeleted = true;
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    DocumentBuilder db = dbf.newDocumentBuilder();
    org.w3c.dom.Document doc = db.parse(file);
    NodeList root = doc.getElementsByTagName("Students");
    NodeList nList2 = doc.getElementsByTagName("student");
    for (int i = 0; i < nList2.getLength(); i++) {
        Node nNode = root.item(0);
        Node nNode2 = nList2.item(i);
        Element eElement2 = (Element) nNode2;

        if (eElement2.getElementsByTagName("Student_id").item(0).getTextContent().equals(std_id)) {
            isDeleted = true;
            nNode.removeChild(nNode2);

        } else if (eElement2.getElementsByTagName("Student_id").item(0).getTextContent() != (std_id)) {
            isDeleted = false;

        }

        DOMSource source = new DOMSource(doc);

        TransformerFactory transformerFactory = TransformerFactory.newInstance();
        Transformer transformer = transformerFactory.newTransformer();
        StreamResult result = new StreamResult(file);
        transformer.transform(source, result);

    }
    System.out.println(isDeleted);
    return isDeleted;
}

这是我在Visual Studio上的代码：

private void Delete_Click(object sender, EventArgs e)
    {

        var student_ID = textBox1.Text.ToString();
        Boolean isDeleted = true;
        ServiceReference1.StudentWSClient myRef = new ServiceReference1.StudentWSClient();
        ServiceReference1.DeleteResponse response = new ServiceReference1.DeleteResponse();
        myRef.Delete(student_ID);
        if (response.@return == isDeleted )
        {
            MessageBox.Show("Student Deleted", "Delete Student", MessageBoxButtons.OK);
            textBox1.Text = "";
        }
        else if(response.@return != isDeleted)
        {
            MessageBox.Show("Student_ID not found or An error has occured!", "Delete Student", MessageBoxButtons.OK);
        }
    }

我想检查元素是否已被删除，然后显示正确的消息框...当删除时我的返回值为TRUE，但是当它在VS上检查其响应时它显示为false，显示＆＃34;未找到Student_ID或者发生了错误！＆＃34; 但元素仍然被删除！有什么原因吗？

Answer 1

isDeleted = myRef.Delete(student_ID);

您尚未将返回值指定给isDeleted，请执行上述操作

Answer 2

每当从列表中删除项目时，总是从头到尾。如果你没有

，索引会搞砸

for (int i = nList2.getLength() - 1; i >= 0; i--)

返回值无效

2 个答案: