JSP问答集 (给初接触jsp者)

怎样搀和运用jsp和ssi #include?在jsp中不妨运用如次办法包括純html：<!--#include file="data.inc"-->然而即使data.inc中包括jsp code ，我們不妨运用：<%@include file="data.inc"%>怎样執行一個線程安定的jsp?只需减少如次训令<br><%@ page isthreadsafe="false" %>jsp怎样處理html form中的資料?通過內置的request物件即可，如次：<%<br>string item = request.getparameter("item");int howmany = new integer(request.getparameter("units")).intvalue();%>在jsp怎样包括一個靜態文献?靜態包括如次：<%@ include file="copyright.html" %>動態包括如次：<jsp:include page="copyright.html" flush="true"/>在jsp中怎样运用注釋?重要有四中本领：1。<%-- 與 --%>2。//3。/**與**/4。<!--與-->在jsp中怎样執行瀏覽重定向?运用如次办法即可：response.sendredirect("http://ybwen.home.chinaren.com/index.html";);也能物理地改變http header屬性，如次：<%response.setstatus(httpservletresponse.sc_moved_permanently);string newlocn="/newpath/index.html";response.setheader("location",newlocn);%>怎样提防在jsp或servlet中的輸出不被browser生存在cache中?把如次腳本介入到jsp文献的開始即可：<%response.setheader("cache-control","no-store"); file://http 1.1response.setheader("pragma","no-cache"); file://http 1.0response.setdateheader ("expires", 0); file://prevents caching at the proxy server%>在jsp中怎样設置cookie?cookie是作?http header的一局部被發送的，如次本领即可設置：<%cookie mycookie = new cookie("aname","avalue");response.addcookie(mycookie);%>在jsp中怎样刪除一個cookie?<%cookie killmycookie = new cookie("mycookie", null);killmycookie.setmaxage(0);killmycookie.setpath("/");response.addcookie(killmycookie);%>在一個jsp的請求處理中怎样遏止jsp的執行?如次例：<%if (request.getparameter("wen") != null) {// do something} else {return;}%>在jsp中怎样定義本领?你不妨定義本领，然而你不许径直訪問jsp的內置物件，而是通過參數的本领傳遞。如次：<%!public string howbadfrom(httpservletrequest req) {httpsession ses = req.getsession();...return req.getremotehost();}%><%out.print("in general,lao lee is not baddie ");%><%= howbadfrom(request) %>即使browser已關閉了cookies，在jsp中我怎样打開session來跟蹤?运用url重寫即可，如次：hello1.jsp<%@ page session="true" %><%integer num = new integer(100);session.putvalue("num",num);string url =response.encodeurl("hello2.jsp");%>hello2.jsp</a>hello2.jsp<%@ page session="true" %><%integer i= (integer )session.getvalue("num");out.println("num value in session is "+i.intvalue());%>在jsp中能發送email嗎?不妨运用sun的專用包：sun.net.smtp包。如次腳本运用smtpclient類發送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 was sent from a jsp page!");message.println();message.println("cool! :-)");message.println();message.println("good boy");message.println("i'm in genius.com");message.println();client.closeserver();}catch (ioexception e){system.out.println("error sending email:"+e);}%>在servlet中我能調用一個jsp錯誤頁嗎?當然沒問題，如次展现了怎样在一個servlet遏制邏輯單元內調用一個jsp錯誤頁面。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();}}}jsp怎样與ejb sessionbean通訊?底下的代碼段作了很好的示範<%@ page import="javax.naming.*, javax.rmi.portableremoteobject,foo.accounthome, foo.account" %><%!file://定義一個對sessionbeanhome介面實例的全部援用accounthome acchome=null;public void jspinit() {file://獲得home介面實例initialcontext cntxt = new initialcontext( );object ref= cntxt.lookup("java:comp/env/ejb/accountejb");acchome = (accounthome)portableremoteobject.narrow(ref,accounthome.class);}%><%file://實例化sessionbeanaccount acct = acchome.create();file://調用遠端本领acct.dowhatever(...);// 如许之类%>