最近使用Tomcat做web服务器,使用Servlet技术做开发时,对Tomcat的框架的简易分析:
疑问: 为什么我们在继承HttpServlet类之后,覆盖doGet(HttpServletRequest req, HttpServetResponse rep)方法后,该方法会自动被Tomcat服务器调用,doGet方法的参数有谁传递过来?怎样传递?
分析之我见: doGet方法的参数由Tomcat服务器在得到客户端(浏览器)的GET请求时自动调用,HttpServletRequest,HttpServetResponse 是两个接口,由Tomcat厂商对接口的实现之后传递过来的。
org.apache.catalina.connector.RequestFacade类实现HttpServletRequest接口。
org.apache.catalina.connector.ResponseFacade类实现HttpServetResponse接口。
那么必定在Tomcat服务器中会有一个main方法,实例化RequestFacade,ResponseFacade对象,并将对象传递到
我们的Servlet对象的doGet方法的参数中。
以下是我简易模拟其实现:
我们在编写Servlet程序时,可以继承该类来实现我们的Servlet:
//这里由Tomcat服务器启动是运行:
public class HttpServlet { public void doGet(HttpServletRequest req, HttpServetResponse rep){ System.out.println("HttpServlet"); } }
public interface HttpServletRequest { public String getPramater(Stirng key); }
public interface HttpServetResponse{ public Writer getWriter(); }
public class requestFacade implements HttpServletRequest { @Override public String getPramater(String key) { // TODO Auto-generated method stub System.out.println("从客户端浏览器获取请求");
return null; } }
public class TomcatHttpServletResponse implements HttpServetResponse { @Override public void getWriter() { // TODO Auto-generated method stub System.out.println("获取客户端的输入流"); } }
//这里就是我们自己编写的Servlet程序了:
public class Tomacat { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub requestFacade req = new requestFacade(); resposeFacade rep = new responseFacade();
Class class = Class.forName("MyServlet"); Object a = class.createnewInstance();
a.doGet(req, rep); } }
public class MyServlet extends HttpServlet { @Override public void doGet(HttpServletRequest req, HttpServetResponse rep) { // TODO Auto-generated method stub PrintWriter w = rep.getWriter(); w.println("hello world"); } }