Why is this redirect not working? JSF

Why is this redirect开发者_如何转开发 not working in my managed bean?

HttpServletRequest objHttpServletRequest = (HttpServletRequest) FacesContext.getCurrentInstance().getExternalContext().getRequest();
        FacesContext.getCurrentInstance().getExternalContext().redirect(objHttpServletRequest.getRequestURI() + "?abc=" + 1 + "&def=" + 2);

I think the problem is caused because of &. If i send just parameter(removing &), it works fine. Thanks in advance :)

Try replacing & with &.