JSP的login程式碼_JSP編程

來源:互聯網
上載者:User
JSP的login程式碼

<!-- 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檔案
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對象

  ·如何獲得一個運行時刻的JSP/Servlet檔案的絕對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());

  ·如何知道用戶端通過哪個URL訪問本頁面

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

  ·如果form中出現好幾個submit按鈕,JSP/Servlet如何判斷哪個按鈕進行了提交在form中可以這樣定義:

<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"),根據傳回值就可進行判斷。

  5.13 include指令

  這個指令讓你可以在JSP編譯成servlet的時候可以包含進一些檔案。這個指令是這樣的:

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

  這個指定的URL通常是指向它的JSP頁面的相關解釋。包含的檔案內容被當作JSP文本來分析,因此可以包含靜態 HTML、scripting elements、directives以及actions。

  例如,很多網站的每個頁面上都包含有小的導航條。這個 include 是做這個的很好方法,省得開發人員經常拷貝HTML到不同的檔案中。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>

  既然檔案是在頁面被編譯的時候插入的,如果導航條改變了,你需要去重新編譯它所指向的所有JSP頁面。注意,問題很容易在這裡出現。一些讀者在改變導航條後,重新運行包含導航條的JSP檔案時,發現導航條不變。原因有兩個:一是前面提到的include指令在JSP編譯成servlet的時候包含進導航條檔案;第二就是JSP檔案是被編譯成servlet之後再啟動並執行,如果伺服器發現JSP檔案沒有被修改,則直接去調用已經編譯好的servlet。如此一來,當調用JSP檔案時,由於直接調用了編譯好的servlet,顯示的結果當然就是以前的導航條了。只要稍微修改一下JSP檔案,該問題就可以自行解決。

  如果導航條不是經常改變的,而且想要整個過程儘可能高效,那麼在這樣的環境下這是好的妥協。 如果這個 included 檔案經常改變,那麼建議讀者使用用 jsp:include 行為(action)來代替。
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