JSP的login程序代码

  • 来源: 互联网 作者: rocket   2008-03-17/13:25
  • <!-- Login Manager -->
    <JAVA TYPE="class">

    public static boolean checkUserPermission(HttpSession mySession, HttpServletRequest request, HttpServletResponse response)
    {
    if (mySession.getValue("hasPermission") == null || !((Boolean) mySession.getValue ("hasPermission" )).booleanValue())
    {
    String requestedUrl = HttpUtils.getRequestURL(request).toString();
    String queryString = request.getQueryString();
    if (queryString != null)
    {
    requestedUrl = requestedUrl + "?" + queryString;
    }
    requestedUrl = response.encodeUrl(requestedUrl);
    mySession.putValue("requestedUrl", requestedUrl);
    return false;
    }
    else
    {
    return true;
    }
    }

    </JAVA>

    <%
    // JSP文件
    String goodUser = "bill";
    String goodPass = "bobo";
    HttpSession mySession = request.getSession(true);
    String errorMessage = "Please Login To Access The Page You Requested";
    boolean loginAttempt = false;
    String myMethod = request.getMethod();
    if (request.getParameterValues("click") != null && request.getParameterValues ("click")[0].trim().equals("Log In"))
    {
    loginAttempt = true;
    }

    if (loginAttempt)
    {
    String username = request.getParameterValues("user")[0].trim();
    String password = request.getParameterValues("pass")[0].trim();
    //out.println("username = |" + username + "| & password = |" + password + "|<BR>");
    if (goodUser.equals(username) && goodPass.equals(password))
    {
    response.sendRedirect((String)mySession.getValue("requestedUrl"));
    mySession.putValue("hasPermission", new Boolean(true));
    errorMessage = "Unable to redirect: " + (String) mySession.getValue("requestedUrl");
    }
    else
    {
    errorMessage = "You did not get the Username or Password right";
    }
    }
    else
    {
    errorMessage = "Haven't tried logging in yet.";
    if (mySession.getValue("requestedUrl") == null)
    {
    mySession.putValue("requestedUrl", "/index.jsp");
    }
    //out.println("set userReferrer to " + mySession.getValue("redirectTo") + "<BR>");
    }
    %>

    <CENTER>
    <font color=red><%=errorMessage%></font>
    <TABLE align=center>
    <FORM action="adminLogin2.jsp" method=post name="login">
    <TR>
    <TD>Username:</TD>
    <TD><input type=text name=user value=""></TD>
    </TR>
    <TR>
    <TD>Password:</TD>
    <TD><input type=password name=pass value=""></TD>
    </TR>
    <TR>
    <TD colspan=2 align=center><input type=submit name=click value="Log In"> </TD>
    </TR>
    </FORM>
    </TABLE>
    </CENTER>
    Original URL: <%= (String)mySession.getValue("requestedUrl") %>
    <script language="Javascript">
    // <!--
    if (document.forms.login != null)
    document.forms.login.user.focus();
    // -->
    </script>

    5.11 checkbox在jsp中的使用方法



    <%@ page language="Java" contentType="text/html" %>
    <%@ page import="com.ora.jsp.util.*" %>
    <html>
    <body bgcolor="white">
    <form action="checkbox.jsp">
    <input type="checkbox" name="fruits" value="Apple">Apple<br>
    <input type="checkbox" name="fruits" value="Banana">Banana<br>
    <input type="checkbox" name="fruits" value="Orange">Orange<br>
    <input type="submit" value="Enter">
    </form>

    <%
    String[] picked = request.getParameterValues("fruits");
    if (picked != null && picked.length != 0) {
    %>
    You picked the following fruits:
    <form>
    <input type="checkbox" name="fruits" value="Apple"
    <%= ArraySupport.contains(picked, "Apple")?"checked" : "" %> >Apple<br>
    <input type="checkbox" name="fruits" value="Banana"
    <%= ArraySupport.contains(picked,"Banana")?"checked":"" %> >Banana<br>
    <input type="checkbox" name="fruits" value="Orange"
    <%= ArraySupport.contains(picked,"Orange")?"checked" : "" %> >Orange<br>
    </form>
    <% } %>
    </body>
    </html>

    5.12 request对象

    ·如何获得一个运行时刻的JSP/Servlet文件的绝对URL地址

    String url = request.getRequestURL();
    if (request.getQueryString() != null)
    {
    url += '?' + request.getQueryString();
    }
    URL theURL = new URL ( request.getScheme() , request.getServerName() , request.getServerPort(),url);
    out.print(URL.toString());

    ·如何知道客户端通过哪个URL访问本页面

    String callingPage = request.getHeader("Referer");
    Out.print(callingPage);

    ·如果form中出现好几个submit按钮,JSP/Servlet如何判断哪个按钮进行了提交在form中可以这样定义:

    <input type=submit name="name" value="john"><br>
    <input type=submit name="name" value="joe"><br>
    在JSP/Servlet中使用request.getParameter("name"),根据返回值就可进行判断。

    5.13 include指令

    这个指令让你可以在JSP编译成servlet的时候可以包含进一些文件。这个指令是这样的:

    <%@ include file="relative url" %>

    这个指定的URL通常是指向它的JSP页面的相关解释。包含的文件内容被当作JSP文本来分析,因此可以包含静态 HTML、scripting elements、directives以及actions。

    例如,很多站点的每个页面上都包含有小的导航条。这个 include 是做这个的很好方法,省得开发者经常拷贝HTML到不同的文件中。例如:

    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
    <HTML>
    <HEAD>
    <TITLE>Servlet Tutorial: JavaServer Pages (JSP) 1.0</TITLE>
    <META NAME="author" CONTENT="webmaster@somesite.com">
    <META NAME="keywords" CONTENT="...">
    <META NAME="description" CONTENT="...">
    <LINK REL=STYLESHEET HREF="Site-Styles.css" TYPE="text/css">
    </HEAD>
    <BODY>
    <%@ include file="/navbar.html" %>
    <!-- Part specific to this page ... -->
    </BODY>
    </HTML>

    既然文件是在页面被编译的时候插入的,如果导航条改变了,你需要去重新编译它所指向的所有JSP页面。注意,问题很容易在这里出现。一些读者在改变导航条后,重新运行包含导航条的JSP文件时,发现导航条不变。原因有两个:一是前面提到的include指令在JSP编译成servlet的时候包含进导航条文件;第二就是JSP文件是被编译成servlet之后再运行的,如果服务器发现JSP文件没有被修改,则直接去调用已经编译好的servlet。如此一来,当调用JSP文件时,由于直接调用了编译好的servlet,显示的结果当然就是以前的导航条了。只要稍微修改一下JSP文件,该问题就可以自行解决。

    如果导航条不是经常改变的,而且想要整个过程尽可能高效,那么在这样的环境下这是好的妥协。 如果这个 included 文件经常改变,那么建议读者使用用 jsp:include 行为(action)来代替。

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