JSP-学习笔记（一）

博客皆个人学习过程中整理，如有问题，欢迎大家指正。

本文链接： https://blog.csdn.net/qq_42017331/article/details/102717943

请求过程：

简单描述其过程就是：当请求到达服务器上的Web容器后，容器通过查找对应的servlet响应此次请求。
详细分析：

• 请求到达web容器
• 容器解析此次请求，并创建一个请求对象和响应对象
• 容器将请求信息设置给上述两个对象（HttpServletRequest和HttpServletResponse)
• 容器根据 @WebServlet标签或者web.xml文件 查找对应的Servlet
• 容器调用service（）方法，将之前设置的HttpServletRequest和HttpServletResponse作为参数传入
• service（）方法会调用对应的doxxx()方法处理此次请求

举例说明：

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class Demo
 */
@WebServlet("/Demo")
public class Demo extends HttpServlet {
 	private static final long serialVersionUID = 1L;  
    		/**
    		 * @see HttpServlet#HttpServlet()
     		*/
    	public Demo() {
        	super();
        	// TODO Auto-generated constructor stub
    	}
    	
 	/**
  	* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
  	*/
 	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws 	ServletException, IOException {
 	 	// TODO Auto-generated method stub
  		response.getWriter().append("Served at: ").append(request.getContextPath());
 	}
 	
 	/**
  	* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
  	*/
 	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  		// TODO Auto-generated method stub
  		doGet(request, response);
 	}
}

容器根据@WebServlet("/Demo")调用Demo类。观察此类可以发现，其继承自HttpServlet类，并且实现了doGet()和doPost()方法。

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  	// TODO Auto-generated method stub
  	doGet(request, response);
 }
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  	// TODO Auto-generated method stub
  	response.getWriter().append("Served at: ").append(request.getContextPath());
 }

上述两个方法，都将HttpServletRequest和HttpServletResponse两个对象作为方法参数。
结果显示：