1. How to mix JSP and SSI #include?
You can include pure HTML in a JSP by using the following methods:
<!--#i nclude file= "Data.inc"-->
But if the data.inc contains JSP CODE, we can use:
<% @include file= "Data.inc"%>
2. How to execute a thread-safe JSP?
Just add the following instructions
<%@ page isthreadsafe= "false"%>
3, JSP How to handle the data in HTML form?
You can use the built-in request object, as follows:
<%
String item = request.getparameter ("item");
int howmany = new Integer (Request.getparameter ("units")). Intvalue ();
%>
4, in the JSP how to include a static file?
The static includes the following: <%@ include file= "copyright.html"%>
The dynamic includes the following: <jsp:include page= "copyright.html" flush= "true"/>
5. How to use annotations in JSP?
There are four main methods:
1. <%--and--%>
2. //
3. /** and **/
4. <!--and-->
6. How to perform browsing redirection in JSP?
The following methods can be used: Response.sendredirect ("http://ybwen.home.chinaren.com/index.html");
You can also physically change the HTTP header properties as follows:
<%
Response.setstatus (httpservletresponse.sc_moved_permanently);
String newlocn= "/newpath/index.html";
Response.setheader ("Location", NEWLOCN);
%>
7, how to prevent the JSP or servlet in the output is not browser saved in the cache?
Add the following script to the beginning of the JSP file:
<%
Response.setheader ("Cache-control", "No-store"); HTTP 1.1
Response.setheader ("Pragma", "No-cache"); HTTP 1.0
Response.setdateheader ("Expires", 0); Prevents caching at the proxy server
%>
8. How to set up cookies in JSP?
Cookies are sent as part of the HTTP header, and you can set the following methods:
<%
Cookie MyCookie = new Cookie ("Aname", "avalue");
Response.addcookie (MyCookie);
%>
9, in the JSP how to delete a cookie?
<%
Cookie Killmycookie = new Cookie ("MyCookie", null);
Killmycookie.setmaxage (0);
Killmycookie.setpath ("/");
Response.addcookie (Killmycookie);
%>
10. How to stop the execution of JSP in the request processing of a JSP
The following example:
<%
if (Request.getparameter ("Wen")!= null) {
Do something
} else {
Return
}
%>
11. How to define methods in JSP
You can define a method, but you cannot directly access the built-in object of the JSP, but rather pass it through the method of the parameter. As follows:
<%!
Public String Howbadfrom (HttpServletRequest req) {
HttpSession ses = req.getsession ();
...
return Req.getremotehost ();
}
%>
<%
Out.print ("In General,lao Lee are not baddie");
%>
<%= Howbadfrom (Request)%>
12, if the browser has been closed cookies, in the JSP how can I open the session to track
You can use URL rewriting as follows:
hello1.jsp
<%@ page session= "true"%>
<%
Integer num = new integer (100);
Session.putvalue ("num", num);
String URL =response.encodeurl ("hello2.jsp");
%>
<a href= "/<";%=url%>>hello2.jsp</a>
hello2.jsp
<%@ page session= "true"%>
<%
Integer i= (integer) session.getvalue ("num");
Out.println ("Num value in the session is" +i.intvalue ());
%>
13, in the JSP can send email?
You can use the Sun's private package: SUN.NET.SMTP package. The following script uses the SmtpClient class to send email.
<%@ page import= "sun.net.smtp.SmtpClient, java.io.*"%>
<%
String from= "ybwen@sina.com";
String to= "hewenjun@yeah.net, lei@who.com.cn";
try{
SmtpClient client = new SmtpClient ("mail.xxxxx.xxx");
Client.from (from);
Client.to (to);
PrintStream message = Client.startmessage ();
Message.println ("to:" + to);
MESSAGE.PRINTLN ("subject:sending email from jsp!");
Message.println ("This is sent from a JSP page!");
Message.println ();
Message.println ("cool!:-)");
Message.println ();
Message.println ("Good Boy");
Message.println ("Im in genius.com");
Message.println ();
Client.closeserver ();
}
catch (IOException e) {
System.out.println ("ERROR Sending EMAIL:" +e);
}
%>
14. Can I call a JSP error page in the servlet?
Of course, the following shows how to invoke a JSP error page within a servlet control logical unit.
protected void Senderrorredirect (HttpServletRequest request,
HttpServletResponse response, String Errorpageurl,
Throwable e)
Throws Servletexception, IOException {
Request.setattribute ("Javax.servlet.jsp.jspException", e);
Getservletconfig (). Getservletcontext ().
Getrequestdispatcher (Errorpageurl). Forward (Request,
Response);
}
public void DoPost (HttpServletRequest request,httpservletresponse response) {
try {
Do something
catch (Exception ex) {
try {
Senderrorredirect (Request,response, "/jsp/myerrorpage.jsp", ex);
catch (Exception e) {
E.printstacktrace ();
}
}
}
15, JSP and applet how to communicate
How JSP communicates with EJB Sessionbean
The following code snippet is a good example of
<%@ page import= "javax.naming.*, Javax.rmi.PortableRemoteObject,
Foo. Accounthome, Foo. Account "%>
<%!
Defines a global reference to an instance of the Sessionbeanhome interface
Accounthome Acchome=null;
public void Jspinit () {
Get Home Interface Instance
InitialContext cntxt = new InitialContext ();
Object ref= cntxt.lookup ("JAVA:COMP/ENV/EJB/ACCOUNTEJB");
Acchome = (accounthome) portableremoteobject.narrow (Ref,accounthome.class);
}
%>
<%
Instantiation of Sessionbean
Account acct = Acchome.create ();
Calling remote methods
Acct.dowhatever (...);
Mailroom
%>
