* XML（Extensible Markup Language，可扩展标记语言）
1、XML DOM解析：
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); DocumentBuilder builder = factory.newDocumentBuilder(); File f = ... Document doc=builder.parse(f); URL u=... Document doc=builder.parse(u); InputStream in=... Document doc=builder.parse(in);2、XML DTD（Document Type Definition，文档类型验证）验证：
XML中验证：<!DOCTYPE configuration [<!Element configuration ...> more rules ...]>外部dtd文件验证：<!DOCTYPE configuration SYSTEM "config.dtd">URL验证：<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN" "http://java.sun.com/j2ee/dtds/web-app_2.2.dtd">3、XML Schema：其本身就是一个XML文件，同时其内容指明了某种XML的格式。
关于dtd和XML Schema文档的编写可以参考《Java核心技术 卷II》Page 152-154中给出的具体文件内容示例。
本文参考 https://blog.csdn.net/bjhecwq/article/details/5872960 中的相关程序！
有关XML文件的介绍可以参阅 https://blog.csdn.net/zoeban/article/details/8617597
实例主要逻辑：
HelloWorld.java提供反射机制访问的类test.xml文件给出HelloWorld类的信息Test.java文件读取xml中的类信息，并利用反射机制生成HelloWorld类的实例，并调用其中的方法具体文件如图所示
各文件内容如下
HelloWorld.java
import java.util.Arrays; public class HelloWorld { public void sayHello(){ System.out.println("sya hello"); } public void sayHello(int i){ System.out.println("sya hello: " + i); } public void sayHello(String[] str){ System.out.println("say hello: " + Arrays.toString(str)); } public static void main(String[] args) { String[] str = {"a", "b"}; HelloWorld h = new HelloWorld(); h.sayHello(str); System.out.println("hello world"); } }test.xml
<?xml version="1.0" encoding="UTF-8"?> <element> <import class="HelloWorld"/> </element>Test.java
import java.io.File; import java.io.FileInputStream; import java.io.InputStream; import java.lang.reflect.Method; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.xml.sax.SAXException; public class Test { /** * @param args * @throws IOException * @throws ParserConfigurationException * @throws SAXException * @throws ClassNotFoundException * @input */ public static void main(String[] args) throws Exception, ParserConfigurationException, SAXException, ClassNotFoundException { DocumentBuilder builder; builder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); if (args.length == 0) return; else { InputStream in=null; try { //读取XML文件 String filePath = args[0]; File file = new File(filePath); in = new FileInputStream(file); Document doc=builder.parse(in); Element eRoot = doc.getDocumentElement(); NodeList nl = eRoot.getChildNodes(); for (int i = 0; i < nl.getLength(); i++) { Node n = nl.item(i); if (!(n instanceof Element)) continue; Element e = (Element) n; System.out.println("Element: " + e.getNodeName()); //取得类名 String className=e.getAttribute("class"); Class cl=Class.forName(className); //创建类实例对象 Object o=cl.newInstance(); //动态调用方法 Method m=cl.getMethod("sayHello", String[].class); Object[] ob=new Object[1]; String arg[]=new String[1]; arg[0]="1"; ob[0]=arg; m.invoke(o,ob); } } finally { in.close(); } } } }具体运行方法：
javac HelloWorld.javajavac -encoding utf-8 Test.javajava Test test.xml输出：
最后文件：
