JSF
如果检测到错误,用户将被重定向到错误页面,在那里他可以给出反馈。然后我尝试读取
ErrorBean
对象然而,有时错误并不存在——存在错误的可能性为50%。
FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap()
它有时返回一个带有1个条目的映射,有时返回一个空映射。在任何情况下,id都是在http级别传递的。
我真的无法重现是什么导致了这一切。以下是相关代码(省略了helper方法+空实现)。ErrorFilter映射在
/*
ErrorBean是由JSF管理的会话范围bean。
public class ErrorFilter implements Filter
{
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException
{
HttpServletRequest hreq = (HttpServletRequest) req;
HttpServletResponse hres = (HttpServletResponse) resp;
try
{
chain.doFilter(req, resp);
}
catch (IOException e)
{
handleError(e, hreq, hres);
}
catch (ServletException e)
{
handleError(e, hreq, hres);
}
catch (RuntimeException e)
{
handleError(e, hreq, hres);
}
}
private static void handleError(Throwable e, HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
{
final RequestInfo requestInfo = new RequestInfo(getUri(req), req.getSession().getId(), null, null, UserFactory.getUser(), InetAddress.getByName(req.getRemoteAddr()));
String token = new DecimalFormat("00000000").format(Math.abs(RANDOM.nextInt() % Integer.MAX_VALUE));
//log msg
//send mail in a different thread
if (!req.getRequestURI().startsWith("/faces/error.jsp"))
{
resp.sendRedirect("/faces/error.jsp?token=" + token);
}
else
{
//log that an infite loop occurred
throw new ServletException(crapMsg, e);
}
}
}
错误豆
public class ErrorBean implements Serializable
{
private String feedback;
private String lastToken;
public String getLastErrorCode()
{
return "your token: " + getToken();
}
private String getToken()
{
final String token = (String) FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("token");
//here the "token" returns null although it is sent via get.
if (token != null)
{
if (!token.equals(lastToken))
{
// reset data on token change.
feedback = null;
}
lastToken = token;
}
return lastToken;
}
public void setFeedback(String feedback)
{
this.feedback = feedback;
}
public String getFeedback()
{
if (feedback == null)
{
feedback = getDefaultMessage();
}
return feedback;
}
public void send()
{
sendMail(lastToken,feedback);
}
}