【IT168技术文档】
之后写XML的测试类,笔者把这个类命名为XMLTest,为了读写XML文件,需要导入如下JAVA包,"//"后为注释说明,笔者的环境是JDK 1.3.1_04,在JDK 1.4.0中测试也通过,XML解释器用Apache的Crimson,可以到Apache主页去上载。
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:import java.io.*; //Java基础包,包含各种IO操作 import java.util.*; //Java基础包,包含各种标准数据结构操作 import javax.xml.parsers.*; //XML解析器接口 import org.w3c.dom.*; //XML的DOM实现 import org.apache.crimson.tree.XmlDocument;//写XML文件要用到
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(); }