dom4j是一个Java的XML API，是jdom的升级品，用来读写XML文件的。dom4j是一个十分优秀的javaXML API，具有性能优异、功能强大和极其易使用的特点，它的性能超过sun公司官方的dom技术，同时它也是一个开放源代码的软件，可以在SourceForge上找到它。
一、dom4j介绍
使用方式：在pom.xml中导入dom4j对应的jar
<dependency>
<groupId>dom4j</groupId>
<artifactId>dom4j</artifactId>
<version>1.6.1</version>
</dependency>
优点：dom4j使Java生成和解析XML灵活性变高，并且代码易于维护。
API操作类：
Document：表示xml文档信息，是一个树形结构
Eelment：表示xml的元素结点，提供一些操作其子元素方法的，如文本、属性、名称空间等
Attribute：表示元素结点中的属性
二、常用API
1.创建Document 和Element对象：
Document doc=DocumentHelper.createDocument();
Element eltRoot=DocumentHelper.createElement("student");
doc.setRootElement(eltRoot);
2.或者先准备好根元素，使用有参数的构造方法创建Document对象。
Element eltRoot=DocumentHelper.createElement(“student”);
Document doc=DocumentHelper.createDocument(eltRoot);
3.添加节点和设置节点内容
Element eltName=eltRoot.addElement(“name”);
Element eltAge=eltRoot.addElement(“age”);
eltName.setText(“张三”);
eltAge.setText(“18”);
4.添加属性
eltRoot.addAttribute(“sn”,”01”);
5.使用 SAXReader 构建dom4j文档对象
SAXReader saxReader=new SAXReader();
File file=new File(“student.xml”);
Document doc=saxReader.read(file);
6.使用DOMReader 构建dom4j 文档对象
DocumentBuilderFactory dbf=new DocumentBuilderFactory.newInstance();
DocumentBuilder db=dbf.newDocumentBuilder();
File file=new File(“student.xml”);
org.w3c.dom.Document document=db.parse(file);
DOMReader domReader=new DOMReader();
org.dom4j.Document doc=domReader.read(document);
7.访问根节点：
Element root=doc.getRootElement();
8.访问所有节点:
java.util.List childrenList=elt.elements();
9.访问指定名称的所有节点
java.util.Liat childrenList=elt.elements(“student”);
10.访问指定名称第一个节点
Element eltChild=elt.element(“student”);
11.要迭代某个元素的所有子元素
for(java.util.Iterator it=root.elementIterator();it.hasNext()){
Element element =it.hasNext();
……
}
输出文档：
对象：XMLWriter 实例方法：write（Document doc）
常用的几种构造方法总结：
1：无参数：
2:字节流参数
3：字符流参数。
4：文档输出格式类参数。
示例代码1：
输出文档内容到控制台
XMLWriter xw=new XMLWriter();
xw.write(doc);
三、dom4j 生成 xml
实现步骤：
第一步：创建一个Document实例
Document doc = DocumentHelper.createDocument();
第二步：先添加一个根结点，然后再添加子结点，构造成一个树形结构
Element root = doc.addElement("root");
第三步：添加xml文件样式（也可自定义样式），并输出xml文件到指定的路径下
OutputFormat format = OutputFormat.createPrettyPrint();
XMLWriter writer = new XMLWriter(new FileOutputStream(file), format);
writer.write(doc);
实现源码
package com.oysept.xml;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
import org.jdom2.output.Format;
/**
* dom4j生成xml
* @author ouyangjun
*/
public class CreateDom4j {
public static void main(String[] args) {
// 执行dom4j生成xml方法
createDom4j(new File("E:\\dom4j.xml"));
}
public static void createDom4j(File file) {
try {
// 创建一个Document实例
Document doc = DocumentHelper.createDocument();
// 添加根节点
Element root = doc.addElement("root");
// 在根节点下添加第一个子节点
Element oneChildElement= root.addElement("person").addAttribute("attr", "root noe");
oneChildElement.addElement("people").addAttribute("attr", "child one").addText("person one child one");
oneChildElement.addElement("people") .addAttribute("attr", "child two") .addText("person one child two");
// 在根节点下添加第一个子节点
Element twoChildElement= root.addElement("person").addAttribute("attr", "root two");
twoChildElement.addElement("people") .addAttribute("attr", "child one").addText("person two child one");
twoChildElement.addElement("people") .addAttribute("attr", "child two").addText("person two child two");
// xml格式化样式
// OutputFormat format = OutputFormat.createPrettyPrint(); // 默认样式
// 自定义xml样式
OutputFormat format = new OutputFormat();
format.setIndentSize(2); // 行缩进
format.setNewlines(true); // 一个结点为一行
format.setTrimText(true); // 去重空格
format.setPadText(true);
format.setNewLineAfterDeclaration(false); // 放置xml文件中第二行为空白行
// 输出xml文件
XMLWriter writer = new XMLWriter(new FileOutputStream(file), format);
writer.write(doc);
System.out.println("dom4j CreateDom4j success!");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
XML文件效果图：
untitled.png
四、dom4j解析xml
实现步骤
第一步：创建一个SAXReader解析器
SAXReader reader = new SAXReader();
第二步：解析xml文件，重新构建成一个Document对象
Document doc = reader.read(file);
第三步：处理Document对象信息，在控制台打印
实现源码：
package com.oysept.xml;
import java.io.File;
import java.util.Iterator;
import java.util.List;
import org.dom4j.Attribute;
import org.dom4j.CDATA;
import org.dom4j.Comment;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.Text;
import org.dom4j.io.SAXReader;
/**
* dom4j解析xml
* @author ouyangjun
*/
public class ParseDom4j {
public static void main(String[] args) {
// 执行dom4j解析xml方法
parseDom4j(new File("E:\\dom4j.xml"));
}
public static void parseDom4j(File file) {
try {
// 创建一个SAXReader解析器
SAXReader reader = new SAXReader();
// 读取xml文件,转换成Document结点
Document doc = reader.read(file);
// 递归打印xml文档信息
StringBuffer buffer = new StringBuffer();
parseElement(doc.getRootElement(), buffer);
System.out.println(buffer.toString());
} catch (DocumentException e) {
e.printStackTrace();
}
}
@SuppressWarnings("unchecked")
public static void parseElement(Element element, StringBuffer buffer) {
buffer.append("<"+element.getName());
List<Attribute> attrs = element.attributes();
if (attrs != null) {
for (Attribute attr : attrs) {
buffer.append(" "+attr.getName()+"=\""+attr.getValue()+"\"");
}
}
buffer.append(">");
Iterator<Node> iterator = element.nodeIterator();
while (iterator.hasNext()) {
Node node = iterator.next();
if (node instanceof Element) {
Element eleNode = (Element) node;
parseElement(eleNode, buffer);
}
if (node instanceof Text) {
Text text = (Text) node;
buffer.append(text.getText());
}
if (node instanceof CDATA) {
CDATA dataNode = (CDATA) node;
buffer.append(dataNode.getText());
}
if (node instanceof Comment) {
Comment comNode = (Comment) node;
buffer.append(comNode.getText());
}
}
buffer.append("</"+element.getName()+">");
}
}
XML文件解析效果图打印：
untitled.png
五、dom4j解析生成字符串
import java.io.IOException;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
/**
*
* @author y
*/
public class Test {
/**
* @param args the command line arguments
*/
public static void main(String[] args) throws DocumentException {
Map<String, Object> map = new HashMap<String, Object>();
map.put("name", "李四");
map.put("age", 25);
//System.out.println(map2xml(map));
List<Object> list = new ArrayList<Object>();
list.add("测试1");
list.add("测试2");
list.add("测试3");
//System.out.println(list2xml(list,"items"));
List<Map<String,Object>> listMap = new ArrayList<Map<String,Object>>();
Map<String,Object> map1 = new HashMap<String,Object>();
map1.put("name", "张三");
map1.put("age", 23);
listMap.add(map1);
map1 = new HashMap<String,Object>();
map1.put("name", "李四");
map1.put("age", 24);
listMap.add(map1);
map1 = new HashMap<String,Object>();
map1.put("name", "王五");
map1.put("age", 25);
listMap.add(map1);
System.out.println(listMap2xml(listMap,"users","user"));
}
public static String listMap2xml(List<Map<String,Object>> list,String listRoot,String mapRoot){
Document doc = DocumentHelper.createDocument();
Element rootEle = doc.addElement("result");
Element noEle = rootEle.addElement("no");
Element msgEle = rootEle.addElement("msg");
if(null!=list && !list.isEmpty()){
noEle.setText("1");
msgEle.setText("成功获取相关信息");
Element listRootEle = rootEle.addElement(listRoot);
for(Map<String,Object> map:list){
Element mapRootELe = listRootEle.addElement(mapRoot);
Set<Map.Entry<String,Object>> set = map.entrySet();
Iterator<Map.Entry<String,Object>> iter = set.iterator();
while(iter.hasNext()){
Map.Entry<String,Object> entry = (Map.Entry<String,Object>)iter.next();
Element ele = mapRootELe.addElement(entry.getKey());
ele.setText(String.valueOf(entry.getValue()));
}
}
}else{
noEle.setText("0");
msgEle.setText("没有获取到相关信息");
}
StringWriter sw = new StringWriter();
OutputFormat format = OutputFormat.createPrettyPrint();
format.setEncoding("utf-8");
try {
XMLWriter xmlWriter = new XMLWriter(sw, format);
xmlWriter.write(doc);
} catch (IOException ex) {
Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
}finally{
try {
sw.close();
} catch (IOException ex) {
Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
}
}
return sw.toString();
}
public static String list2xml(List<Object> list,String itemRoot){
Document doc = DocumentHelper.createDocument();
Element rootEle = doc.addElement("result");
Element noEle = rootEle.addElement("no");
Element msgEle = rootEle.addElement("msg");
if(null!=list && !list.isEmpty()){
noEle.setText("1");
msgEle.setText("成功获取相关信息");
Element itemRootEle = rootEle.addElement(itemRoot);
for(Object obj:list){
Element ele = itemRootEle.addElement("item");
ele.setText(String.valueOf(obj));
}
}else{
noEle.setText("0");
msgEle.setText("没有获取到相关信息");
}
StringWriter sw = new StringWriter();
OutputFormat format = OutputFormat.createPrettyPrint();
format.setEncoding("utf-8");
try {
XMLWriter xmlWriter = new XMLWriter(sw, format);
xmlWriter.write(doc);
} catch (IOException ex) {
Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
}finally{
try {
sw.close();
} catch (IOException ex) {
Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
}
}
return sw.toString();
}
public static String map2xml(Map<String, Object> map) {
Document doc = DocumentHelper.createDocument();
Element rootEle = doc.addElement("result");
Element noEle = rootEle.addElement("no");
Element msgEle = rootEle.addElement("msg");
if(null!=map && !map.isEmpty()){
noEle.setText("1");
msgEle.setText("成功获取相关信息");
Set<Map.Entry<String, Object>> set = map.entrySet();
Iterator<Map.Entry<String, Object>> iter = set.iterator();
while(iter.hasNext()){
Map.Entry<String, Object> entry = (Map.Entry<String, Object>) iter.next();
Element ele = rootEle.addElement(entry.getKey());
ele.setText(String.valueOf(entry.getValue()));
}
}else{
noEle.setText("0");
msgEle.setText("没有获取到相关信息");
}
StringWriter sw = new StringWriter();
OutputFormat format = OutputFormat.createPrettyPrint();
format.setEncoding("utf-8");
try {
XMLWriter xmlWriter = new XMLWriter(sw, format);
xmlWriter.write(doc);
} catch (IOException ex) {
Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
}finally{
try {
sw.close();
} catch (IOException ex) {
Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
}
}
return sw.toString();
}
public static void test4() {
Document doc = DocumentHelper.createDocument();
Element rootEle = doc.addElement("sudent");
Element nameEle = rootEle.addElement("name");
nameEle.setText("张三");
Element ageEle = rootEle.addElement("age");
ageEle.setText("25");
try {
StringWriter sw = new StringWriter();
OutputFormat format = OutputFormat.createPrettyPrint();
format.setEncoding("utf-8");
XMLWriter xmlWriter = new XMLWriter(sw, format);
xmlWriter.write(doc);
System.out.println(sw.toString());
} catch (IOException ex) {
Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
}
}
public static void test3() throws DocumentException {
String str = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>"
+ "<books>"
+ " <book>"
+ " <name>Think in Java</name>"
+ " <price>120.0</price>"
+ " <chapters>"
+ " <c>001</c>"
+ " <c>002</c>"
+ " <c>003</c>"
+ " </chapters>"
+ " </book>"
+ " <book>"
+ " <name>Think in Java2</name>"
+ " <price>220.0</price>"
+ " </book>"
+ "</books>";
Document doc = DocumentHelper.parseText(str);
Element books = doc.getRootElement();
List<Element> childEles = books.elements();
Iterator<Element> iter = childEles.iterator();
while (iter.hasNext()) {
Element book = iter.next();
Element name = book.element("name");
Element price = book.element("price");
System.out.println("name:" + name.getText() + ",price:" + price.getText());
Element chapters = book.element("chapters");
if (null != chapters) {
Iterator<Element> chaptersIter = chapters.elementIterator();
if (null != chaptersIter) {
while (chaptersIter.hasNext()) {
Element c = chaptersIter.next();
System.out.println("===>" + c.getText());
}
}
}
}
}
public static void test2() throws DocumentException {
String str = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>"
+ "<books>"
+ " <book>"
+ " <name>Think in Java</name>"
+ " <price>120.0</price>"
+ " </book>"
+ " <book>"
+ " <name>Think in Java2</name>"
+ " <price>220.0</price>"
+ " </book>"
+ "</books>";
Document doc = DocumentHelper.parseText(str);
Element books = doc.getRootElement();
List<Element> childEles = books.elements();
Iterator<Element> iter = childEles.iterator();
while (iter.hasNext()) {
Element book = iter.next();
Element name = book.element("name");
Element price = book.element("price");
System.out.println("name:" + name.getText() + ",price:" + price.getText());
}
}
public static void test1() throws DocumentException {
String str = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>"
+ "<dzswdjz>"
+ " <qr_code>"
+ " <nsrsbh>nsrsbh</nsrsbh >"
+ " <retStatus >retStatus</retStatus>"
+ " <img_name>img_name</img_name>"
+ " <img_byteString>img_byteString</img_byteString>"
+ " </qr_code>"
+ "</dzswdjz>";
Document doc = DocumentHelper.parseText(str);
//获取到父节点
Element dzswdjz = doc.getRootElement();
//定位到qr_code节点
Element qr_code = dzswdjz.element("qr_code");
Element nsrsbh = qr_code.element("nsrsbh");
Element retStatus = qr_code.element("retStatus");
Element img_name = qr_code.element("img_name");
Element img_byteString = qr_code.element("img_byteString");
System.out.println("nsrsbh:" + nsrsbh.getText());
System.out.println("retStatus:" + retStatus.getText());
System.out.println("img_name:" + img_name.getText());
System.out.println("img_byteString:" + img_byteString.getText());
}
}
