使用技巧：Java程序开发中如何应用线程

来源：中国IT实验室作者：佚名出处：巧巧读书 2008-05-19 进入讨论组

    //**************************************   隐藏域技术的登录表单生成Servlet
    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 HiddenField extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {

      response.setContentType("text/html;charset=gb2312");
      PrintWriter out = response.getWriter();
      int validationCode=(int)(Math.random()*1000);
      out.println("<HTML>");
      out.println("<HEAD><TITLE>隐藏域</TITLE></HEAD>");
      out.println("<BODY><h2>通过隐藏域实现会话管理</h2><hr>");
      out.println("<form action='Login' method=post>");
      out.println("用户名:<input type=text width=10 name='username' value='abc'><br>");
      out.println("密码:　<input type=password width=10 name='password' value='123'><br>");
      out.println("验证码:<input type=text width=10 name='inputedcode'>"+validationCode);
      out.println("<input type=hidden width=10 name='code' value='"+validationCode+"'>");
      out.println("<input type=submit value='登录'><br>");
      out.println("</form>");
      out.println("</BODY>");
      out.println("</HTML>");
      out.flush();
      out.close();
     }
    }

    //**************************************   URL重写和隐藏域技术的登录验证Servlet
    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 LoginWithUrlRedirect extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

      response.setContentType("text/html;charset=gb2312");
      PrintWriter out = response.getWriter();
      out.println("<BODY><h2>通过URL重写实现会话管理</h2><hr>");
      out.println("用户名:"+request.getParameter("username")+"<br>");
      out.println("密码:　"+request.getParameter("password")+"<br>");
      out.println("系统验证码:"+request.getParameter("code")+"<br>");
      out.println("输入验证码:"+request.getParameter("inputedcode")+"<br>");
      out.println("</BODY>");
      out.flush();
      out.close();
     }

    }
    //**************************************   Cookie技术的登录表单生成Servlet
    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;
    import javax.servlet.http.Cookie;

public class CookieManagement extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {

      response.setContentType("text/html;charset=gb2312");
      PrintWriter out = response.getWriter();
      int validationCode=(int)(Math.random()*1000);
      Cookie myCookie=new Cookie("code",""+validationCode);
      myCookie.setMaxAge(60*60);   //一小时
      response.addCookie(myCookie);
      out.println("<HTML>");
      out.println("<HEAD><TITLE>Cookie</TITLE></HEAD>");
      out.println("<BODY><h2>通过Cookie实现会话管理</h2><hr>");
      out.println("<form action='LoginWithCookie' method=post>");
      out.println("用户名:<input type=text width=10 name='username' value='abc'><br>");
      out.println("密码:　<input type=password width=10 name='password' value='123'><br>");
      out.println("验证码:<input type=text width=10 name='inputedcode'>"+validationCode);
      out.println("<input type=submit value='登录'><br>");
      out.println("</form>");
      out.println("</BODY>");
      out.println("</HTML>");
      out.flush();
      out.close();
     }
    }
    //**************************************   Cookie技术的登录验证Servlet
    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;
    import javax.servlet.http.Cookie;