Jsp&Servlet學習筆記（5）
阿新 • • 發佈：2020-12-16
第五章Servlet 開發
第一節：Hello Servlet !
Web.xml配置servlet名稱、對映等，此處略。
package com.java1234.web;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HelloWorldServlet extends HttpServlet{
/** * */ private static final long serialVersionUID = 1L; @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println("get"); this.doPost(request, response); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setCharacterEncoding("gbk"); PrintWriter out=response.getWriter(); out.println("<html>"); out.println("<head><title>Hello Servlet !</title></head>"); out.println("Hello Servlet !"); out.println("</html>"); out.close(); }
}
第二節：servlet 生命週期
Servlet 的生命週期，簡單的概括這就分為四步：servlet 類載入—>例項化—>服務—>銷燬。
第三節：客戶端跳轉VS 伺服器端跳轉
1，在Servlet 中獲取session,application
2，客戶端跳轉response.sendRedirect(“目標地址”);
//web.xml配置同上
@Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setAttribute("requestKey", "request值"); HttpSession session=request.getSession(); // 獲取session session.setAttribute("sessionKey", "session值"); ServletContext application=this.getServletContext(); // 獲取application application.setAttribute("applicationKey", "application值"); response.sendRedirect("target.jsp"); // 客戶端跳轉/重定向 }
//target.jsp
目標地址
request值：<%=request.getAttribute(“requestKey”) %>
session值：<%=session.getAttribute(“sessionKey”) %>
application值：<%=application.getAttribute(“applicationKey”) %>
(sendRedirect重定向不攜帶request引數)
