Java Web 会话编程（Session）

　　会话结束：

　　　　浏览器关闭；

　　　　主动关闭；

　　　　会话超时；

　　会话的底层实现方法：

　　　　cookies；

　　　　URL重写；

Example：

DemoSessionServlet.java

代码：

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Date;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class DemoSessionServlet extends HttpServlet {
private static final long serialVersionUID = 3144436730239445373L;

public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}

public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  HttpSession session = request.getSession();
  Integer counter = (Integer) session.getAttribute("counter");
  if (counter == null) {
   counter = new Integer(1);
  } else {
   counter = new Integer(counter.intValue() + 1);
  }
  session.setAttribute("counter", counter);
  session.setMaxInactiveInterval(3600);

response.setContentType("text/html;charset=UTF-8");
 PrintWriter out = response.getWriter();
 out.println("<html>");
 out.println("<head><title>session demo servlet</title></head>");
 out.println("<body>");
 out.println("<h1>使用session的演示</h1>");
 out.println("你已经访问了" + counter + "次. ");
 if (session.isNew()) {
 out.println("这是一个新建的Session. ");
 } else {
 out.println("这不是一个新建的Session. ");
 }
 out.println("jsessionid: " + session.getId() + " ");
 out.println("LastAccessedTime: " + session.getLastAccessedTime() + " ");
 out.println("格式转换以后的LastAccessedTime: " + new Date(session.getLastAccessedTime()) + " ");
 out.println("CreationTime: " + session.getCreationTime() + " ");
 out.println("格式转换以后的CreationTime: " + new Date(session.getCreationTime()) + " ");
 out.println("MaxInactiveInterval: " + session.getMaxInactiveInterval() + "秒 ");
 out.println(" 使用Session对象的getAttributeNames ");
 Enumeration enumer = session.getAttributeNames();
 String name = null;
 while (enumer.hasMoreElements()) {
 name = (String) enumer.nextElement();
 out.println("Session name:" + name + " ");
 out.println("Session value:" + session.getAttribute(name) + " ");
 }
 // session.removeAttribute("counter");

//移除或者注销session
 // session.invalidate();
 out.println("</body>");
 out.println("</html>");
 out.flush();
 out.close();
}
}