[Jweb] Session -- SessionInfoServlet.java / ShowSession.java / URLSession.java

Session, Session 是一个篮子

只要是同一套有父子关系的窗口，都可以访问到同一个 Session。
启发：默认 session 是依赖 cookie 的。若cookie完全禁用后解决方案：重写URL。
新浪邮箱：做学问不严谨。不像IBM等这样的大公司。
+ "<a href=" + response.encodeURL(request.getRequestURL().toString()) + ">test</a><BR>"
+ "<a href=" + request.getRequestURI().toString() + ">test</a>"
china-pub买书，例如：最近浏览的列表，一般是写cookie里面了。

Session , Session 是一个篮子

china-pub买书，例如：最近浏览的列表，一般是写cookie里面了。

SessionInfoServlet.java

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;

/**
 * 用于演示Servlet API中的Session管理机制
 */
public class SessionInfoServlet extends HttpServlet {
    /**
     * Builds an HTML document containing session information and returns it to
     * the client.
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // get current session or, if necessary, create a new one
        HttpSession mySession = request.getSession(true);

        // MIME type to return is HTML
        response.setContentType("text/html");

        // get a handle to the output stream
        PrintWriter out = response.getWriter();

        // generate HTML document
        out.println("<HTML>");
        out.println("<HEAD>");
        out.println("<TITLE>Session Info Servlet</TITLE>");
        out.println("</HEAD>");
        out.println("<BODY>");
        out.println("<H3>Session Information</H3>");
        out.println("New Session: " + mySession.isNew());
        out.println("<BR>Session ID: " + mySession.getId());
        out.println("<BR>Session Creation Time: "
                + new java.util.Date(mySession.getCreationTime()));
        out.println("<BR>Session Last Accessed Time: "
                + new java.util.Date(mySession.getLastAccessedTime()));

        out.println("<H3>Request Information</H3>");
        out.println("Session ID from Request: "
                + request.getRequestedSessionId());
        out.println("<BR>Session ID via Cookie: "
                + request.isRequestedSessionIdFromCookie());
        out.println("<BR>Session ID via rewritten URL: "
                + request.isRequestedSessionIdFromURL());
        out.println("<BR>Valid Session ID: "
                + request.isRequestedSessionIdValid());

        out.println("</BODY></HTML>");

        out.close(); // close output stream
    }

    /**
     * Returns a brief description of this servlet.
     * 
     * @return Brief description of servlet
     */
    public String getServletInfo() {
        return "Servlet returns session information.";
    }
}

--ShowSession.java

import java.io.*;
import java.net.*;
import java.util.*;

import javax.servlet.*;
import javax.servlet.http.*;

// Session 追踪

public class ShowSession extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        String title = "Session Tracking Example";
        HttpSession session = request.getSession(true); // 在服务器端找不到则创建一个，这是 true 的含义，客户端带不回来
        String heading;
        // Use getAttribute instead of getValue in version 2.2.
        Integer accessCount = (Integer) session.getAttribute("accessCount"); // 计数的功能
        if (accessCount == null) {
            accessCount = new Integer(0);
            heading = "Welcome, Newcomer";
        } else {
            heading = "Welcome Back";
            accessCount = new Integer(accessCount.intValue() + 1);
        }
        // Use setAttribute instead of putValue in version 2.2.
        session.setAttribute("accessCount", accessCount);

        out.println("<html><head><title>Session追踪</title></head>"
                + "<BODY BGCOLOR="#FDF5E6">
" + "<H1 ALIGN="CENTER">"
                + heading
                + "</H1>
"
                + "<H2>Information on Your Session:</H2>
"
                + "<TABLE BORDER=1 ALIGN="CENTER">
"
                + "<TR BGCOLOR="#FFAD00">
"
                + "  <TH>Info Type<TH>Value
"
                + "<TR>
"
                + "  <TD>ID
"
                + "  <TD>"
                + session.getId()
                + "
"
                + "<TR>
"
                + "  <TD>Creation Time
"
                + "  <TD>"
                + new Date(session.getCreationTime())
                + "
"
                + "<TR>
"
                + "  <TD>Time of Last Access
"
                + "  <TD>"
                + new Date(session.getLastAccessedTime())
                + "
"
                + "<TR>
"
                + "  <TD>Number of Previous Accesses
"
                + "  <TD>"
                + accessCount + "
" + "</TABLE>
" + "</BODY></HTML>");

    }

    /** Handle GET and POST requests identically. */

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

URLSession.java

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.net.*;
import java.util.*;

//Session追踪

public class URLSession extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		
		HttpSession session = request.getSession(true);

		out.println("<html><head><title>Session追踪</title></head>"
				+ "<BODY>
"
				+ "session id:" + session.getId() + "<br>"
				+ "from url:" + request.isRequestedSessionIdFromURL() + "<br>"
				+ "from cookie:" + request.isRequestedSessionIdFromCookie() + "<br>" 
				+ "<a href=" + response.encodeURL(request.getRequestURL().toString()) + ">test</a><BR>" 
				+ "<a href=" + request.getRequestURI().toString() + ">test</a>" 
				+ "</BODY></HTML>");

	}

	/** Handle GET and POST requests identically. */

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