JSP内置对象编程窍门
发布时间：2023-06-03 13:31:05 所属栏目：教程 来源：
导读：JSP内置对象编程技巧
1.1 application
*在jsp中获得application对象
如：getservletcontext().setattribute("counter",new mycount.counter());
如：<jsp:usebean scope="application" id="counter"
1.1 application
*在jsp中获得application对象
如：getservletcontext().setattribute("counter",new mycount.counter());
如：<jsp:usebean scope="application" id="counter"
|
JSP内置对象编程技巧 1.1 application *在jsp中获得application对象 如：getservletcontext().setattribute("counter",new mycount.counter()); 如：<jsp:usebean scope="application" id="counter" class="mycounter.counter"/> *在jsp中处理on application start和on session start事件的方法 使用httpsessionbindinglistener类. 添加session: session.putvalue("bingdings.listener",new mylistener(getservletcontext()); 定义mylistener类： import javax.servlet.http.*; import javax.servlet.*; public class mylistener implements httpsessionbindinglistener{ servletcontext context; public mylistener(servletcontext context){ this.context=context; } public void valuebound(httpsessionbindingevent event){ system.out.println("valuebound:someone just bound my listener to a session!"); } public void valueunbound(httpsessionbindingevent event){ system.out.println("valueunbound:someone just unbound my listener!"); } } 1.2 request *获取一个正在运行时的jsp/servlet文件的绝对url地址 stringf file=request.getrequesturl(); if(requet.getquerystring()!=null{ file+='?'+request.getquerystring(); } url reconstructedurl=new url(request.getscheme(),request.getservername(),request.getserverport(),file); out.println(reconstructedurl.tostring()); *获取客户端通过哪一个url访问本页面 string callpage=request.getheader("referer"); *获取当前脚本在当疥文件系统中的真实路径 request.getrealpath(request.getservletpath()); *判断多个submit中的一个 <input type=submit name="sub" value="up"> <input type=submit name="sub" value="down"> 在jsp中使用request.getparameter("sub");就可分辨 1.3 response *网页重定向之三方法 (1)response.sendredirect(url); (2)<%response.setstatus(httpservletresponse.sc_moved_premanently); string nowloc="/newpath/index.htm"; response.setheader("location",newloc);%> (3)<jsp:forward page="/newpage.jsp"/> 注意上法只能在任何输出还没有发送到客户端之前使用这种方法 *禁用缓存 <%response.setheader("cache-control","no-store"); response.setdateheader("expires",0);%> 1.4 session *存活时间 <%session.setmaxinactiveinterval(300);%> *注销 session.invalidate(); 1.5 exception *在jsp页面中处理servlet的错误 protected void senderrorredirect(httpservletrequest request, httpservletresponse response,string errorpageurl,throwable e) throws servletexception,ioexception{ request.setattibute("javax.servlet.jsp.jspexception",e); getservletconfig().getservletcontext(); getrequestdispatcher(errorpageurl).forward(request,response); } public void dopost(httpservletrequest request,httpservletresponse response){ try{ // } catch(exception e){try{ senderrorredirect(request,response,"/jsp/errpage.jsp",e); }catch(exception e){e.printstacktrace();} } } *在jsp页面中输出错误的stacktrace (1) <%@ page iserrorpage="true%> <% out.println("<pre>"); printwriter pw=response.getwriter(); exception.printstacktrace(pw); out.println("</pre>"); %> (2) <%@ page iserrorpage="true%> <pre> <% exception.printstacktrace(new printwriter(out)); %> </pre> 1.6 cookie *设置cookie <% cookie mycookie=new cookie("aname","avalue"); response.addcookie(mycookie); //mycookie.setmaxage(time); %> 。 （编辑：聊城站长网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
站长推荐
