1. Client: JSP
<% @ Page Language = "Java" pageencoding = "GBK" %> <HTML>
2. SERVER: servlet
Package servlet; import Java. io. ioexception; import Java. io. printwriter; import javax. servlet. servletexception; import javax. servlet. HTTP. httpservlet; import javax. servlet. HTTP. httpservletrequest; import javax. servlet. HTTP. httpservletresponse; public class SERVERPORT extends httpservlet {Private Static final long serialversionuid = 1l; Public void dopost (httpservletrequest request, httpservletresponse respo AUC) throws servletexception, ioexception {response. setcontenttype ("text/html; charset = GBK"); string username = request. getparameter ("username"); printwriter out = response. getwriter (); If (username. trim (). length () = 0 | username = NULL) {out. println ("<font color = 'red'> the user name cannot be blank! </Font> ");} else if (" neyjar ". Equals (username) {out. println (" <font color = 'red'> the user already exists! </Font> ");} else {out. println (" <font color = 'blue'> you can use this user name! </Font> ") ;}} public void doget (httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {dopost (request, response );}}
3. Configure the servlet in Web. xml:
<Servlet> <servlet-Name> servletport </servlet-Name> <servlet-class> servlet. SERVERPORT </servlet-class> </servlet> <servlet-mapping> <servlet-Name> servletport </servlet-Name> <URL-pattern>/SERVERPORT </url-Pattern> </servlet-mapping>
This is all!