1. Set Cookies
The code is as follows
Cookie cookie = new Cookie ("Key", "value");
Cookie.setmaxage (60);
Sets a 60-second lifetime, and if set to a negative value, the browser process cookie (saved in memory) is invalidated when the browser is closed.
The code is as follows
Cookie.setpath ("/test/test2");
Sets the cookie path, not set as the current path (for the servlet, the Url-pattern path portion of the servlet configured in Request.getcontextpath () + web.xml).
The code is as follows
Response.addcookie (cookie);
2. Read cookies
The method can read the current path and all the cookie objects of the direct parent path, or null if there are no cookies.
The code is as follows
cookie[] cookies = request.getcookies ();
3. Delete Cookies
The code is as follows
Cookie cookie = new Cookie ("key", null);
Cookie.setmaxage (0);
Set to 0 to delete the cookie immediately;
The code is as follows
Cookie.setpath ("/test/test2");
Deletes the cookie on the specified path, and does not set the path by default to delete the current path cookie;
The code is as follows Response.addcookie (cookie);
The following is a complete example to illustrate
The code is as follows
<%@ page contenttype= "text/html; Charset=utf-8 "language=" java "import=" java.sql.* "errorpage=" "%>"
<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "http://www.3lian.com/" >
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 "/>
<title></title>
<body>
<%
String username = null;
cookie[] cookies = reques T.getcookies ();
if (cookies!=null)
{
for (int i=0;i<cookies.length;i++)
{
if ("Cookies_user". Equals (Cookies[i].getname ()))
{
username = Cookies[i].getvalue ();//cookies_user}
}
if ("Onepc". Equals (username))
{
out.println ("Hello");
&NBSP;&NBsp; }else
{
%>
<table width= "302" border= "1"
<form id= "Form1" Name= "Form1" method= "Post" action= "clogin.jsp"
<tr>
<td width= "><div" align= "center" ></DIV></TD>
<TD width= "207" ><input type= "text" name= "user" id= "user"/></TD>
</tr>
& nbsp <tr>
<td><div align= "center" ></DIV></TD>
<td><input type= "text" name= "textfield2" id= "Textfield2"/></TD>
</tr>
& nbsp <tr>
<td><div align= "center" >
</div></td>
<td><select name= "Select" id= "select"
<option value= "31536000" >one year</option>
<option value= ">two" MIN</OPTION>
</select></td
</TR>
<TR>
<TD Colspan= "2" ><label>
<input type= "Submit" name= "button" id= "button" Value= ""/>
</label></td>
</tr>
</form>
</table>
<%
}
}
%>
</body>
login.jsp
The code is as follows
<%
String user = Request.getparameter ("user");
Cookie cookie = new Cookie ("Cookies_user", user);
Cookie.setmaxage (120);
Response.addcookie (cookie);
Response.sendredirect ("cindex.jsp");
%>
4. Note: Suppose the path structure is as follows
The code is as follows
test/test2/test345/test555/test666
A. Cookies with the same key name (values can be the same or different) can exist under different paths.
B. At the time of deletion, if there is no cookie with the key "key" under the current path, query all the parent paths and retrieve the delete operation (only one with its closest parent path cookie at a time) FF. You must specify the same path to use when setting cookies to remove the cookie, and the cookie's key name, regardless of uppercase, lowercase, or mixed size, specifies the path. IE. When the key name is lowercase, if the current path is/TEST/TEST2, if you can not find the/test,/test555,/test345, if you can not find the query/(/test555/test666 do not query). When a key name is mixed or uppercase, the current path is deleted by default without specifying a path and is not queried up.
C. Cookies can only be read from a direct parent path when reading cookies. If the current path is/test/test2, the key to read is "key". After the current path is read, also read the/test,/test read/.
D. When doing Java Web projects, because a typical Web server (such as Tomcat or jetty) uses the context to manage different Web application, there is a different path for each context, and there are multiple web Application should be particularly cautious, do not set path to/cookies, easy to operate (if the premise is the same domain name).
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