Servlet cookie value assignment and value processing method and page-based pre-pass value processing method. The following describes how to obtain and set values for cookies, and then detailed the servlet cookie instance operation using an instance.
Import java. io. IOException;
Import java. io. PrintWriter;Import javax. servlet. ServletException;
Import javax. servlet. http. Cookie;
Import javax. servlet. http. HttpServlet;
Import javax. servlet. http. HttpServletRequest;
Import javax. servlet. http. HttpServletResponse;Public class AddCookieServlet extends HttpServlet {
Public void doPost (HttpServletRequest request, HttpServletResponse response)
Throws ServletException, IOException {
String data = request. getParameter ("data ");
Cookie cookie = new Cookie ("MyCookie", data );
Response. addCookie (cookie );
Response. setContentType ("text/html ");
PrintWriter pw = response. getWriter ();
Pw. println ("<B> MyCookie has been set ");
Pw. println (data );
Pw. close ();
}
}
Cookie acquisition
Import java. io. IOException;
Import java. io. PrintWriter;Import javax. servlet. ServletException;
Import javax. servlet. http. Cookie;
Import javax. servlet. http. HttpServlet;
Import javax. servlet. http. HttpServletRequest;
Import javax. servlet. http. HttpServletResponse;Public class GetCookiesServlet extends HttpServlet {
Public void doGet (HttpServletRequest request, HttpServletResponse response)
Throws ServletException, IOException {Cookie [] cookies = request. getCookies ();
Response. setContentType ("text/html ");
PrintWriter pw = response. getWriter ();
Pw. println ("<B> ");
For (int I = 0; I <cookies. length; I ++ ){
String name = cookies [I]. getName ();
String value = cookies [I]. getValue ();
Pw. println ("name =" + name + "; value =" + value );
}
Pw. close ();
}
}
Based on the above example, let's take a look at the transmission between servlet cookie pages.
Import java. io .*;
Import javax. servlet .*;
Import javax. servlet. http .*;
Import java. util .*;Public class MyServlet extends HttpServlet {
Public void doGet (HttpServletRequest request, HttpServletResponse response)
Throws ServletException, java. io. IOException {
Cookie cookie = null;
// Get an array of Cookies associated with this domain
Cookie [] cookies = request. getCookies ();
Boolean newCookie = false;
// Get the 'mycooker' Cookie if it exists
If (cookies! = Null ){
For (int I = 0; I <cookies. length; I ++ ){
If (cookies [I]. getName (). equals ("mycookie ")){
Cookie = cookies [I];
}
} // End
} // End if
If (cookie = null ){
NewCookie = true;
// Get the cookie's Max-Age from a context-param element
// If the 'cookie-age' param is not set properly
// Then set the cookie to a default of-1, 'Never expires'
Int maxAge;
Try {
MaxAge = new Integer (getServletContext (). getInitParameter ("cookie-age"). intValue ();
} Catch (Exception e ){
MaxAge =-1;
}
// Create the Cookie object
Cookie = new Cookie ("mycookie", "" + getNextCookieValue ());
Cookie. setPath (request. getContextPath ());
Cookie. setMaxAge (maxAge );
Response. addCookie (cookie );
} // End if
// Get some info about the cookie
Response. setContentType ("text/html ");
Java. io. PrintWriter out = response. getWriter ();
Out. println ("Out. println ("Out. println ("<title> Cookie info </title> ");
Out. println ("Out. println ("<body> ");
Out. println ("
Out. println ("Cookie value:" + cookie. getValue () + "<br> ");
If (newCookie ){
Out. println ("Cookie Max-Age:" + cookie. getMaxAge () + "<br> ");
Out. println ("Cookie Path:" + cookie. getPath () + "<br> ");
}
Out. println ("</body> ");
Out. println ("
Out. close ();
}
Private long getNextCookieValue (){
/* This produces a cookie value to show how to create Cookie objects. If
This method was heavily used in a production environment it may
Produce too prepare objects; synchronization of a single Date object
Might be better, based on performance testing. At any rate
Production environment wowould produce a unique cookie value in
Different manner such as from a unique database ID .*/// Returns the number of milleseconds since Jan 1, 1970
Return new java. util. Date (). getTime ();
}
Public void doPost (HttpServletRequest request, HttpServletResponse response)
Throws ServletException, java. io. IOException {
DoGet (request, response );
}
}
<? Xml version = "1.0" encoding = "ISO-8859-1"?><! DOCTYPE web-app
PUBLIC "-// Sun Microsystems, Inc. // DTD Web Application 2.2 // EN"
Http://java.sun.com/j2ee/dtds/web-app_2_2.dtd><Web-app>
<Servlet> <servlet-name> MyServletName </servlet-name>
<Servlet-class> MyServlet </servlet-class>
<Init-param>
<Param-name>
Go
</Param-name>
<Param-value>
Weather
</Param-value>
</Init-param>
</Servlet>
<Servlet-mapping> <servlet-name> MyServletName </servlet-name>
<Url-pattern>/index.html </url-pattern>
</Servlet-mapping>
</Web-app>
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