一、利用dom4j创建一个内容如下的xml文件SqlMapConfig.xml
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <!DOCTYPE configuration PUBLIC "-//ibatis.apache.org//DTD Config 3.0//EN" 3 "ibatis-3-config.dtd"> 4 <configuration> 5 <environments default="development"> 6 <environment id="MySQL"> 7 <transactionManager type="JDBC">123</transactionManager> 8 <dataSource type="POOLED"> 9 <property name="driver" value="com.mysql.jdbc.Driver"/> 10 <property name="url" value="jdbc:mysql://127.0.0.1:3306/test"/> 11 <property name="username" value="root"/> 12 <property name="password" value="admin"/> 13 </dataSource> 14 </environment> 15 </environments> 16 17 <mappers> 18 <mapper resource="com/pojo/sql/DepMap.xml"/> 19 <mapper resource="com/pojo/sql/EmpMap.xml"/> 20 </mappers> 21 </configuration>
步骤：
1.创建一个输出流，指定创建的SqlMapConfig.xml文件的位置-------OutputStream
OutputStream os = new FileOutputStream("d:/SqlMapConfig.xml");
2.创建一个xml编写器-------XMLWriter
XMLWriter writer = new XMLWriter(os,OutputFormat.createPrettyPrint());
这里os是前面新建的一个输出流，OutputFormat.createPrettyPrint()是指定输出的格式的，这里代表内容缩进。
3.创建xml文档-------Document、DocumentHelper
Document document = DocumentHelper.createDocument();
4.创建里面的所有结点元素-------Elemenet
Element configuration = document.addElement("configuration");
..............
新建结点元素的形式是：Element 子结点 = 父节点.addElement("子结点名");
给结点元素添加属性是：结点.addAttribute("属性名", "属性值");
5.保存xml
writer.write(document);
代码如下：
1 public class CreateXML { 2 3 /** 4 * @param args 5 * @throws IOException 6 */ 7 public static void main(String[] args) throws IOException { 8 //创建一个输出流，指定创建的xml文件的位置 9 OutputStream os = new FileOutputStream("d:/SqlMapConfig.xml"); 10 11 XMLWriter writer = new XMLWriter(os,OutputFormat.createPrettyPrint()); 12 13 //创建Document 14 Document document = DocumentHelper.createDocument(); 15 16 Element configuration = document.addElement("configuration"); 17 18 Element environments = configuration.addElement("environments"); 19 environments.addAttribute("default", "development"); 20 21 Element environment = environments.addElement("environment"); 22 environment.addAttribute("id", "MySQL"); 23 Element transactionManager = environment.addElement("transactionManager"); 24 transactionManager.addAttribute("type", "JDBC"); 25 transactionManager.setText("123"); 26 27 Element dataSource = environment.addElement("dataSource"); 28 dataSource.addAttribute("type", "POOLED"); 29 Element driver = dataSource.addElement("property"); 30 driver.addAttribute("name", "driver"); 31 driver.addAttribute("value", "com.mysql.jdbc.Driver"); 32 Element url = dataSource.addElement("property"); 33 url.addAttribute("name", "url"); 34 url.addAttribute("value", "jdbc:mysql://127.0.0.1:3306/test"); 35 Element username = dataSource.addElement("property"); 36 username.addAttribute("name", "username"); 37 username.addAttribute("value", "root"); 38 Element password = dataSource.addElement("property"); 39 password.addAttribute("name", "password"); 40 password.addAttribute("value", "admin"); 41 42 Element mappers = configuration.addElement("mappers"); 43 Element mapper1 = mappers.addElement("mapper"); 44 mapper1.addAttribute("resource", "com/pojo/sql/DepMap.xml"); 45 Element mapper2 = mappers.addElement("mapper"); 46 mapper2.addAttribute("resource", "com/pojo/sql/EmpMap.xml"); 47 //保存xml 48 writer.write(document); 49 writer.close(); 50 } 51 }
二、查找xml文件的内容
查找xml文件内容有两种情况，第一种就是查找出所有同名的结点元素然后遍历、第二种就是直接找到某个结点元素
比如遍历SqlMapConfig.xml,将driver、url、username、password的值读取出来就有两种方法，代码如下
方法一：
1 public class GetNodes { 2 3 /**方法一： 4 * 遍历新建的xml,将driver、url、username、password的值读取出来 5 * @param args 6 * @throws IOException 7 * @throws DocumentException 8 */ 9 public static void main(String[] args) throws IOException, DocumentException { 10 SAXReader reader = new SAXReader(); 11 Document document = reader.read("d:/SqlMapConfig.xml"); 12 List<Element> elements = document.selectNodes("/configuration/environments/environment/dataSource/property"); 13 String driver = ""; 14 String url = ""; 15 String username = ""; 16 String password = ""; 17 for (Element e : elements) { 18 String name = e.attributeValue("name"); 19 String value = e.attributeValue("value"); 20 if("driver".equals(name)){ 21 driver = value; 22 }else if("url".equals(name)){ 23 url = value; 24 }else if("username".equals(name)){ 25 username = value; 26 }else if("password".equals(name)){ 27 password = value; 28 } 29 } 30 System.out.println("driver:"+driver+",url:"+url+",username:"+username+",password:"+password); 31 } 32 }
这里List<Element> elements = document.selectNodes("/configuration/environments/environment/dataSource/property")是指将名为property的结点元素全部找出来，用一个List接收。
方法二：
1 public class GetNodes1 { 2 3 /**方法二： 4 * 将driver、url、username、password的值读取出来 5 * @param args 6 * @throws IOException 7 * @throws DocumentException 8 */ 9 public static void main(String[] args) throws IOException, DocumentException { 10 SAXReader reader = new SAXReader(); 11 Document document = reader.read("d:/SqlMapConfig.xml"); 12 Element driverElement = (Element)document.selectSingleNode("/configuration/environments/environment/dataSource/property[@name='driver']"); 13 Element urlElement = (Element)document.selectSingleNode("/configuration/environments/environment/dataSource/property[@name='url']"); 14 Element usernameElement = (Element)document.selectSingleNode("/configuration/environments/environment/dataSource/property[@name='username']"); 15 Element passwordElement = (Element)document.selectSingleNode("/configuration/environments/environment/dataSource/property[@name='password']"); 16 String driver = driverElement.attributeValue("value"); 17 String url = urlElement.attributeValue("value"); 18 String username = usernameElement.attributeValue("value"); 19 String password = passwordElement.attributeValue("value"); 20 21 System.out.println("driver:"+driver+",url:"+url+",username:"+username+",password:"+password); 22 } 23 }
这种方法就没有遍历了，就是直接将要查找的结点找出来，用selectSingleNode()函数。这里的[@name='driver']是指名找到哪一个property结点，相当于一个键值对，表示找有name="driver"属性的property结点。
形式为[@属性名='属性值']。
三、修改XML文件
步骤：
1.读取要修改的xml文件
2.查找到要修改的结点
3.保存
代码如下：
1 public class UpdateNode { 2 3 /** 4 * 修改密码为123456 5 * @param args 6 * @throws DocumentException 7 * @throws IOException 8 */ 9 public static void main(String[] args) throws DocumentException, IOException { 10 //读取并修改 11 SAXReader reader = new SAXReader(); 12 Document document = reader.read("d:/SqlMapConfig.xml"); 13 Element passwordElement = (Element)document.selectSingleNode("/configuration/environments/environment/dataSource/property[@name='password']"); 14 passwordElement.addAttribute("value", "123456"); 15 //保存 16 OutputStream os = new FileOutputStream("d:/SqlMapConfig.xml"); 17 XMLWriter writer = new XMLWriter(os,OutputFormat.createPrettyPrint()); 18 writer.write(document); 19 writer.close(); 20 os.close(); 21 } 22 23 }
四、删除XML文件的某个结点元素
删除和修改一样，也是要先找到要删除的结点，然后删除之，最后保存修改过的文件。删除结点的形式为：父节点.remove(子节点);
代码如下：
1 public class DeleteNode { 2 3 /** 4 * 删除密码结点 5 * @param args 6 * @throws DocumentException 7 * @throws IOException 8 */ 9 public static void main(String[] args) throws DocumentException, IOException { 10 //找到结点并删除 11 SAXReader reader = new SAXReader(); 12 Document document = reader.read("d:/SqlMapConfig.xml"); 13 Element passwordElement = (Element) document.selectSingleNode("/configuration/environments/environment/dataSource/property[@name='password']"); 14 passwordElement.getParent().remove(passwordElement); 15 16 //保存 17 OutputStream os = new FileOutputStream("d:/SqlMapConfig.xml"); 18 XMLWriter writer = new XMLWriter(os,OutputFormat.createPrettyPrint()); 19 writer.write(document); 20 writer.close(); 21 os.close(); 22 } 23 }