dom4j-1.6.1.jar
commons-io-2.4.jar

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;

public class TestReadXMLString {
    public static void main(String[] args) throws DocumentException {
        String readline = "<?xml version=/"1.0/" encoding=/"utf-8/"?><students><student sid=/"001/"> <id>001</id><name>灰機</name> <age>18</age> </student></students>";
        Document document = DocumentHelper.parseText(readline);
        Element rootElm = document.getRootElement();
        System.out.println("rootElement:  " + rootElm.getName());
        Element student = rootElm.element("student");
        Element id = student.element("id");
        Element name = student.element("name");
        Element age = student.element("age");
        System.out.println(id.getText());
        System.out.println(name.getText());
        System.out.println(age.getText());
    }
}

import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
public class TestWriteXMLString {
    public static void main(String[] args) {
        OutputFormat format = OutputFormat.createPrettyPrint();
        // 1. 構造空的Document
        Document doc = DocumentHelper.createDocument();
        doc.addComment("this is a comment");
        // 2. 構造根元素
        Element rootElmt = doc.addElement("users");
        rootElmt.addNamespace("test", "www.test.com");

        Element userElmt = rootElmt.addElement("user");
        userElmt.addAttribute("number", "1001");
        userElmt.addElement("name").setText("zhangsan");
        userElmt.addElement("age").setText("20");
        userElmt.addElement("gender").setText("mail");

        Element userElmt2 = rootElmt.addElement("user");
        userElmt.addAttribute("number", "1002");
        userElmt2.addElement("name").setText("zhangsan");
        userElmt2.addElement("age").setText("20");
        userElmt2.addElement("gender").setText("mail");

        System.out.println(doc.asXML().replaceAll("/n", ""));
    }
}

SAXReader reader = new SAXReader();
String path = "E:/Workspaces/MyEclipse 8.6/xmltest/file/student.xml";
Document document = reader.read(new File(path));

OutputFormat format = OutputFormat.createPrettyPrint();
format.setEncoding("utf-8");// 設置XML文件的編碼格式
String filePath = "E:/Workspaces/MyEclipse 8.6/xmltest/file/student.xml";
Document document = DocumentHelper.createDocument();
doc.addComment("this is a comment");

XMLWriter writer = new XMLWriter(new FileWriter(filePath), format);//寫入指定的文件
writer.write(document);
 writer.close();