DOM4J解析XML
一、DOM4J解析XML文档的实例
book.xml
<?xml version="1.0" encoding="UTF-8"?> <书架> <书> <书名>JavaSE基础</书名> <作者>张三</作者> <售价>38.00</售价> <内部价>19.00</内部价> </书> <书> <书名>Android</书名> <作者>李四</作者> <售价>28.00</售价> </书> </书架>
DOM4JDemo.java
package cn.lsl.dom4j; import java.io.FileOutputStream; import java.io.OutputStream; import java.util.List; import org.dom4j.Document; import org.dom4j.DocumentHelper; import org.dom4j.Element; import org.dom4j.Node; import org.dom4j.io.OutputFormat; import org.dom4j.io.SAXReader; import org.dom4j.io.XMLWriter; import org.junit.Test; public class DOM4JDemo { //1.得到某个具体节点的内容：第二本书的作者 @Test public void test1() throws Exception{ //得到Document对象 SAXReader reader = new SAXReader(); Document document = reader.read("src/book.xml"); //得到根元素 Element root = document.getRootElement(); //依次得到第二本书的作者 List<Element> es = root.elements("书"); Element e = es.get(1); Element author = e.element("作者"); System.out.println(author.getText()); } //使用XPath方式得到第二本书的作者 @Test public void test2() throws Exception{ //得到Document对象 SAXReader reader = new SAXReader(); Document document = reader.read("src/book.xml"); String xpath = "//书[2]/作者"; Node author = document.selectSingleNode(xpath); System.out.println(author.getText()); } //遍历所有元素的节点 @Test public void test3() throws Exception{ //得到Document对象 SAXReader reader = new SAXReader(); Document document = reader.read("src/book.xml"); //得到根元素 Element root = document.getRootElement(); treeWalk(root); } private void treeWalk(Element root) { System.out.println(root.getName()); List<Element> es = root.elements(); for (Element e : es) { treeWalk(e); } } //修改某个元素节点的主题内容：修改第2本书的售价 @Test public void test4() throws Exception{ //得到Document对象 SAXReader reader = new SAXReader(); Document document = reader.read("src/book.xml"); //得到根元素 Element root = document.getRootElement(); Element secondBook = (Element)root.elements().get(1); Element secondBookPrice = secondBook.element("售价"); //设置主题内容 secondBookPrice.setText("28.00"); //写回XML文档 OutputStream out = new FileOutputStream("src/book.xml"); OutputFormat format = OutputFormat.createPrettyPrint(); XMLWriter writer = new XMLWriter(out, format); writer.write(document); writer.close(); } //向指定元素节点中增加子元素节点：给第一本书添加批发价 @Test public void test5() throws Exception{ SAXReader reader = new SAXReader(); Document document = reader.read("src/book.xml"); Element root = document.getRootElement(); Element firstBook = root.element("书"); firstBook.addElement("批发价").setText("18.00"); //写回XML文档 OutputStream out = new FileOutputStream("src/book.xml"); OutputFormat format = OutputFormat.createPrettyPrint(); XMLWriter writer = new XMLWriter(out, format); writer.write(document); writer.close(); } //向指定元素节点上增加同级元素节点：在第一本书的售价前面添加内部价 @Test public void test6() throws Exception{ SAXReader reader = new SAXReader(); Document document = reader.read("src/book.xml"); Element root = document.getRootElement(); //得到第一本书 Element firstBook = root.element("书"); //得到第一本书的所有子元素：List List<Element> children = firstBook.elements(); //借组DocumentHelper创建内部价元素 Element price = DocumentHelper.createElement("内部价"); price.setText("19.00"); children.add(3, price); //写回XML文档中 OutputStream out = new FileOutputStream("src/book.xml"); OutputFormat format = OutputFormat.createPrettyPrint(); XMLWriter writer = new XMLWriter(out, format); writer.write(document); writer.close(); } //删除指定节点元素：删除批发价 @Test public void test7() throws Exception{ SAXReader reader = new SAXReader(); Document document = reader.read("src/book.xml"); Element root = document.getRootElement(); Element firstBook = root.element("书"); Element price = firstBook.element("批发价"); firstBook.remove(price); //写回XML文档中 OutputStream out = new FileOutputStream("src/book.xml"); OutputFormat format = OutputFormat.createPrettyPrint(); XMLWriter writer = new XMLWriter(out, format); writer.write(document); writer.close(); } //操作XML文件属性：第一本书添加一个出版社属性 @Test public void test8() throws Exception{ SAXReader reader = new SAXReader(); Document document = reader.read("src/book.xml"); Element root = document.getRootElement(); Element firstBook = root.element("书"); firstBook.addAttribute("出版社","清华大学出版社"); //写回XML文档中 OutputStream out = new FileOutputStream("src/book.xml"); OutputFormat format = OutputFormat.createPrettyPrint(); XMLWriter writer = new XMLWriter(out, format); writer.write(document); writer.close(); } //获取第一本书的出版社属性 @Test public void test9() throws Exception{ SAXReader reader = new SAXReader(); Document document = reader.read("src/book.xml"); Element root = document.getRootElement(); Element firstBook = root.element("书"); String value = firstBook.attributeValue("出版社"); System.out.println(value); } }
二、案例（学生成绩的增删改查，采用分层开发和DOM4J进行操作）
首先需要导入dom4j.jar和jaxen.jar
exam.xml
<?xml version="1.0" encoding="UTF-8"?> <exam> <student examid="444" idcard="333"> <name>李四</name> <location>大连</location> <grade>97</grade> </student> </exam>
实体类：Student.java
package cn.lsl.domain; public class Student { private String idcard; private String examid; private String name; private String location; private Double grade; public String getIdcard() { return idcard; } public void setIdcard(String idcard) { this.idcard = idcard; } public String getExamid() { return examid; } public void setExamid(String examid) { this.examid = examid; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getLocation() { return location; } public void setLocation(String location) { this.location = location; } public Double getGrade() { return grade; } public void setGrade(Double grade) { this.grade = grade; } @Override public String toString() { return "Student [examid=" + examid + ", grade=" + grade + ", idcard=" + idcard + ", location=" + location + ", name=" + name + "]"; } }
工具类：Dom4JUtil.java
package cn.lsl.util; import java.io.FileOutputStream; import java.io.OutputStream; import org.dom4j.Document; import org.dom4j.io.OutputFormat; import org.dom4j.io.SAXReader; import org.dom4j.io.XMLWriter; public class Dom4JUtil { public static Document getDocument() throws Exception{ SAXReader reader = new SAXReader(); return reader.read("src/exam.xml"); } public static void writer2xml(Document document) throws Exception{ OutputStream out = new FileOutputStream("src/exam.xml"); OutputFormat format = OutputFormat.createPrettyPrint(); XMLWriter writer = new XMLWriter(out, format); writer.write(document); writer.close(); } }
接口：StudentDaoImpl.java
package cn.lsl.dao.impl; import cn.lsl.domain.Student; public interface StudentDaoImpl { //添加学生信息到XML中 boolean createStudent(Student s); //根据准考证好查询学生信息 Student findStudent(String examid); //根据学生姓名删除学生 boolean deleteStudent(String name); }
DAO层：StudentDao.java
package cn.lsl.dao; import java.util.List; import org.dom4j.Document; import org.dom4j.Element; import org.dom4j.Node; import cn.lsl.dao.impl.StudentDaoImpl; import cn.lsl.domain.Student; import cn.lsl.util.Dom4JUtil; public class StudentDao implements StudentDaoImpl { @Override public boolean createStudent(Student s) { boolean result = false; try{ Document document = Dom4JUtil.getDocument(); Element root = document.getRootElement(); Element studentE = root.addElement("student") .addAttribute("examid", s.getExamid()) .addAttribute("idcard", s.getIdcard()); studentE.addElement("name").setText(s.getName()); studentE.addElement("location").setText(s.getLocation()); studentE.addElement("grade").setText(s.getGrade()+""); Dom4JUtil.writer2xml(document); result = true; }catch(Exception e){ throw new RuntimeException(e); } return result; } @Override public boolean deleteStudent(String name) { boolean result = false; try{ Document document = Dom4JUtil.getDocument(); //选择所有的name元素 List<Node> nodes = document.selectNodes("//name"); //遍历 for (Node n : nodes) { if(n.getText().equals(name)) n.getParent().getParent().remove(n.getParent()); } Dom4JUtil.writer2xml(document); result = true; }catch(Exception e){ throw new RuntimeException(e); } return result; } @Override public Student findStudent(String examid) { Student s = null; try{ Document document = Dom4JUtil.getDocument(); Node node = document.selectSingleNode("//student[@examid='"+examid+"']"); if(node!=null){ Element e = (Element)node; s = new Student(); s.setExamid(examid); s.setIdcard(e.valueOf("@idcard")); s.setName(e.element("name").getText()); s.setLocation(e.elementText("location")); s.setGrade(Double.parseDouble(e.elementText("grade"))); } }catch(Exception e){ throw new RuntimeException(e); } return s; } }
View层：Main.java
package cn.lsl.view; import java.io.BufferedReader; import java.io.InputStreamReader; import cn.lsl.dao.StudentDao; import cn.lsl.domain.Student; public class Main { public static void main(String[] args) { try{ StudentDao dao = new StudentDao(); System.out.println("a、添加学生\tb、删除学生\tc、查询成绩"); System.out.println("请输入操作类型"); BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); String operation = br.readLine(); if("a".equals(operation)){ //添加操作 System.out.println("请输入学生姓名"); String name = br.readLine(); System.out.println("请输入学生准考证号"); String examid = br.readLine(); System.out.println("请输入学生身份证号"); String idcard = br.readLine(); System.out.println("请输入学生所在地"); String location = br.readLine(); System.out.println("请输入学生成绩"); String grade = br.readLine(); Student s = new Student(); s.setExamid(examid); s.setIdcard(idcard); s.setName(name); s.setLocation(location); s.setGrade(Double.parseDouble(grade)); //System.out.println(s); boolean b = dao.createStudent(s); if(b){ System.out.println("---添加成功---"); }else{ System.out.println("对不起！数据有误"); } }else if("b".equals(operation)){ System.out.println("请输入要删除的学生姓名:"); String name = br.readLine(); boolean b = dao.deleteStudent(name); if(b){ System.out.println("--删除成功--"); }else{ System.out.println("对不起！删除失败或者学生不存在"); } }else if("c".equals(operation)){ //查询操作 System.out.println("请输入要查询的学生准考证号:"); String examid = br.readLine(); Student s = dao.findStudent(examid); if(s == null){ System.out.println("对不起！您查询的学生不存在"); }else{ System.out.println(s); } }else{ System.out.println("请输入正确的操作类型"); } }catch(Exception e){ System.out.println("对不起！服务器忙！"); } } }