//写XML文件要用到
为了保存多个学生信息,还得借助一个集合类(并不是单纯意义上的集合,JAVA中的集合是集合框架的概念,包含向量、列表、哈希表等),这里采用Vector向量类。定义在XMLTest测试类中,命名为student_Vector。然后定义两个方法readXMLFile和writeXMLFile,实现读写操作。代码如下:
private void readXMLFile(String inFile) throws Exception {
//为解析XML作准备,
创建DocumentBuilderFactory实例,指定DocumentBuilder
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = null;
try {
db = dbf.newDocumentBuilder();
} catch (ParserConfigurationException pce) {
System.err.println(pce);
//出异常时输出异常信息,然后退出,下同
System.exit(1);
}
Document doc = null;
try {
doc = db.parse(inFile);
} catch (DOMException dom) {
System.err.println(dom.getMessage());
System.exit(1);
} catch (IOException ioe) {
System.err.println(ioe);
System.exit(1);
}
//下面是解析XML的全过程,
比较简单,先取根元素"学生花名册"
Element root = doc.getDocumentElement();
//取"学生"元素列表
NodeList students = root.getElementsByTagName("学生");
for (int i = 0; i < students.getLength(); i++) {
//依次取每个"学生"元素
Element student = (Element) students.item(i);
//创建一个学生的Bean实例
StudentBean studentBean = new StudentBean();
//取学生的性别属性
studentBean.setSex(student.getAttribute("性别"));
//取"姓名"元素,下面类同
NodeList names = student.getElementsByTagName("姓名");
if (names.getLength() == 1) {
Element e = (Element) names.item(0);
Text t = (Text) e.getFirstChild();
studentBean.setName(t.getNodeValue());
}
NodeList ages = student.getElementsByTagName("年龄");
if (ages.getLength() == 1) {
Element e = (Element) ages.item(0);
Text t = (Text) e.getFirstChild();
studentBean.setAge(Integer.parseInt(t.getNodeValue()));
}
NodeList phones = student.getElementsByTagName("电话");
if (phones.getLength() == 1) {
Element e = (Element) phones.item(0);
Text t = (Text) e.getFirstChild();
studentBean.setPhone(t.getNodeValue());
}
student_Vector.add(studentBean);
}
}
private void writeXMLFile(String outFile) throws Exception {
//为解析XML作准备,
创建DocumentBuilderFactory实例,指定DocumentBuilder
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = null;
try {
db = dbf.newDocumentBuilder();
} catch (ParserConfigurationException pce) {
System.err.println(pce);
System.exit(1);
}
Document doc = null;
doc = db.newDocument();
//下面是建立XML文档内容的过程,
先建立根元素"学生花名册"
Element root = doc.createElement("学生花名册");
//根元素添加上文档
doc.appendChild(root);
//取学生信息的Bean列表
for (int i = 0; i < student_Vector.size(); i++) {
//依次取每个学生的信息
StudentBean studentBean = (StudentBean) student_Vector.get(i);
//建立"学生"元素,添加到根元素
Element student = doc.createElement("学生");
student.setAttribute("性别", studentBean.getSex());
root.appendChild(student);
//建立"姓名"元素,添加到学生下面,下同
Element name = doc.createElement("姓名");
student.appendChild(name);
Text tName = doc.createTextNode(studentBean.getName());
name.appendChild(tName);
Element age = doc.createElement("年龄");
student.appendChild(age);
Text tAge = doc.createTextNode(String.valueOf(studentBean.getAge()));
age.appendChild(tAge);
Element phone = doc.createElement("电话");
student.appendChild(phone);
Text tPhone = doc.createTextNode(studentBean.getPhone());
phone.appendChild(tPhone);
}
//把XML文档输出到指定的文件
FileOutputStream outStream = new FileOutputStream(outFile);
OutputStreamWriter outWriter = new OutputStreamWriter(outStream);
((XmlDocument) doc).write(outWriter, "GB2312");
outWriter.close();
outStream.close();
}
最后加入测试主函数,如下:
public static void main(String[] args) throws Exception {
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