反射&&xml

模拟Servlet

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://www.example.org/web-app_2_5" 
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://www.example.org/web-app_2_5 web-app_2_5.xsd"
      version="2.5">
      <servlet>
        <servlet-name>MyServlet</servlet-name>
        <servlet-class>xml.dom4j.MyServlet</servlet-class>
      </servlet>
      <servlet-mapping>
        <servlet-name>MyServlet</servlet-name>
        <url-pattern>/myServlet</url-pattern>
      </servlet-mapping>
</web-app>

IServlet接口

package xml.dom4j;

public interface IServlet {

  public void init();

  public void service();

  public void destory();
}

MyServlet类

package xml.dom4j;

public class MyServlet implements IServlet {

  @Override
  public void init() {
    // TODO Auto-generated method stub
    System.out.println("myServlet初始化！");
  }

  @Override
  public void service() {
    // TODO Auto-generated method stub
    System.out.println("myServlet开始服务！");
  }

  @Override
  public void destory() {
    // TODO Auto-generated method stub
    System.out.println("myServlet销毁了！");
  }

}

TestMyServlet类

package xml.dom4j;

import java.lang.reflect.Method;

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

public class TestMyServlet {

  @Test
  public void TestServlet() {

    try {
      SAXReader sr = new SAXReader();
      Document doc = sr.read("src/xml/dom4j/web.xml");
      Element rootElement = doc.getRootElement();
      String className = rootElement.element("servlet").element("servlet-class").getText();
      // System.out.println(className);
      // 根据名称获取其对应的字节码文件对象
      Class clazz = Class.forName(className);
      MyServlet ms = (MyServlet) clazz.newInstance();
      // 直接调用
      // ms.init();
      // ms.service();
      // ms.destory();
      /*
       * 调用字节码文件对象的方法getMethod获取class对象所表示的类的公共成员方法(指定方法)，
       * 参数为方法名和当前方法的参数，无需创建对象，它是静态方法
       * 
       * 调用class对象所表示的类的公共成员方法，需要指定对象和方法中的参数列表
       */
      Method method1 = clazz.getMethod("init", null);
      Method method2 = clazz.getMethod("service", null);
      Method method3 = clazz.getMethod("destory", null);
      method1.invoke(ms, null);
      method2.invoke(ms, null);
      method3.invoke(ms, null);

    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }
}