Servlet 操作Session示例分享
下文是笔者借助HttpSession对象创建一个记录当前客户端访问服务器的次数的示例，
代码中运用了HttpSession的一些方法对Session进行操作，如下所示:
例:
本示例是基于Servlet HelloWorld扩展开发
代码中运用了HttpSession的一些方法对Session进行操作，如下所示:
例:
本示例是基于Servlet HelloWorld扩展开发
/** ServletSessionTest.java **/ package servlet01; import java.io.IOException; import java.io.PrintWriter; import java.text.SimpleDateFormat; import java.util.Date; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; @WebServlet("/SessionTest") public class ServletSessionTest extends HttpServlet { private static final long serialVersionUID = 99L; @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // 当不存在 session 会话，则创建一个 session 对象 HttpSession session = req.getSession(true); // 获取session 创建时间 Date createTime = new Date(session.getCreationTime()); // 获取该网页的最后一次访问时间 Date lastAccessTime = new Date(session.getLastAccessedTime()); // 设置日期输出的格式 SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String title = "Java265.com-Servlet Session Sample test"; Integer visitCount = 0; String visitCountKey = new String("参观人数"); String userIdKey = new String("userId"); String userId = new String("Java265.com"); if (session.getAttribute(visitCountKey) == null) { session.setAttribute(visitCountKey, 0); } // 检查网页上是否有新的访问者 if (session.isNew()) { title = "Java265.com-Servlet Session Sample test"; session.setAttribute(userIdKey, userId); } else { visitCount = (Integer) session.getAttribute(visitCountKey); visitCount = visitCount + 1; userId = (String) session.getAttribute(userIdKey); } session.setAttribute(visitCountKey, visitCount); // 避免中文乱码 resp.setContentType("text/html;charset=UTF-8"); PrintWriter out = resp.getWriter(); String docType = "<!DOCTYPE html>\n"; out.println(docType + "<html>\n" + "<head><title>" + title + "</title></head>\n" + "<body bgcolor=\"#f0f0f0\">\n" + "<h5 align=\"center\">" + title + "</h5>\n" + "<h6 align=\"center\">Session 信息</h6>\n" + "<table border=\"1\" align=\"center\">\n" + "<tr bgcolor=\"#949494\">\n" + " <th>Session 信息</th><th>值</th></tr>\n" + "<tr>\n" + " <td>SessionId</td>\n" + " <td>" + session.getId() + "</td></tr>\n" + "<tr>\n" + " <td>第一次访问时间</td>\n" + " <td>" + df.format(createTime) + " </td></tr>\n" + "<tr>\n" + " <td>最后访问时间</td>\n" + " <td>" + df.format(lastAccessTime) + " </td></tr>\n" + "<tr>\n" + " <td>用户信息</td>\n" + " <td>" + userId + " </td></tr>\n" + "<tr>\n" + " <td>访问总次数：</td>\n" + " <td>" + visitCount + "</td></tr>\n" + "</table>\n" + "</body></html>"); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req, resp); } }
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