实现servlet

package cn.itheima.web.servlet1;

public interface IMyServlet {

	public void init();

	public void service();

	public void destory();
}

package cn.itheima.web.servlet1;

public class MyServlet1 implements IMyServlet{

	@Override
	public void init() {
		System.out.println("MyServlet1诞生了……");
	}

	@Override
	public void service() {
		System.out.println("MyServlet1开始服务了……");
	}

	@Override
	public void destory() {
		System.out.println("MyServlet1销毁了……");
	}

}

package cn.itheima.web.servlet1;

public class MyServlet2 implements IMyServlet{

	@Override
	public void init() {
		System.out.println("MyServlet2诞生了……");
	}

	@Override
	public void service() {
		System.out.println("MyServlet2开始服务了……");
	}

	@Override
	public void destory() {
		System.out.println("MyServlet2销毁了……");
	}

}

package cn.itheima.web.servlet1;

import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.junit.Test;

public class TestMyServlet {
	
	@Test
	public void testMyServlet(){
		try {
			//1.创建解析器对象
			SAXReader saxReader = new SAXReader();
			//2.使用解析器加载web.xml文件得到document对象
			Document document = saxReader.read("src/cn/itheima/web/servlet1/web.xml");
			//3.获取根元素节点
			Element rootElement = document.getRootElement();
			//4.根据元素名称获取子元素节点
			Element servletElement = rootElement.element("servlet");
			//5.根据元素名称获取servlet-class的文本节点
			String servletClass = servletElement.element("servlet-class").getText();
			//System.out.println(servletClass);
			//6.通过类全名获取字节码文件
			Class clazz = Class.forName(servletClass);
			//7.创建实例对象
			MyServlet1 my = (MyServlet1) clazz.newInstance();
			//8.调用实例对象里面的方法
			my.init();
			my.service();
			my.destory();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

package cn.itheima.web.servlet1;

import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.List;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.junit.Before;
import org.junit.Test;

public class TestMyServlet2 {
	//8.创建一个map集合
	private HashMap data = new HashMap();
	
	@Before
	public void testReadWEBXml(){
		try {
			//1.创建解析器对象
			SAXReader saxReader = new SAXReader();
			//2.使用解析器加载web.xml文件得到document对象
			Document document = saxReader.read("src/cn/itheima/web/servlet1/web.xml");
			//3.获取根元素节点
			Element rootElement = document.getRootElement();
			//4.获取子节点(servlet和servlet-mapping)
			List childElements = rootElement.elements();
			//5.遍历
			for (Element element : childElements) {
				//6.判断元素的名称为servlet的元素节点
				if("servlet".equals(element.getName())){
					//7.分别获取servlet元素节点的servlet-name和servlet-class的值
					String servletName = element.element("servlet-name").getText();
					String servletClass = element.element("servlet-class").getText();
					/*System.out.println(servletName);
					System.out.println(servletClass);*/
					data.put(servletName, servletClass);
				}
				//9.判断元素的名称为servlet-mapping的元素节点
				if("servlet-mapping".equals(element.getName())){
					//10.分别获取servlet元素节点的servlet-name和servlet-class的值
					String servletName = element.element("servlet-name").getText();
					String urlPattern = element.element("url-pattern").getText();
					//11.将servletName作为key来获取servletClass的值
					String servletClass = data.get(servletName);
					//12.将url-pattern作为key,servletClass作为value存到map中去
					data.put(urlPattern, servletClass);
					//13.移除servletName
					data.remove(servletName);
				}
			}
			//System.out.println(data);
			
		} catch (DocumentException e) {
			e.printStackTrace();
		}
	}
	
	@Test
	public void testMyServlet(){
		try {
			//1.模拟在浏览器输入一个url
			String url1 = "/myServlet2";
			//2.将urlPattern作为key来获取servletClass
			String className = data.get(url1);
			//3.通过servletClass获取字节码文件
			Class clazz = Class.forName(className);
			//4.通过字节码文件创建实例对象
			Object obj = clazz.newInstance();
			//5.通过字节码文件获取方法(两个参数：第一个是方法名称；第二个参数是方法的参数)
			Method method = clazz.getMethod("service", null);
			//6.调用invoke方法执行实例对象里面的方法(前面写的方法init)【两个参数：第一个是调用方法的实例对象，第二个是方法的实参】
			method.invoke(obj, null);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

web.xml

	
		MyServlet1
		cn.itheima.web.servlet1.MyServlet1
	
	
		MyServlet1
		/myServlet1
	
	
		MyServlet2
		cn.itheima.web.servlet1.MyServlet2
	
	
		MyServlet2
		/myServlet2