在backing bean中添加JavaScript代码输出到客户端

http://hi.baidu.com/jsfcn/blog/item/228101553aa2fdc0b645ae14.html

FacesContext ctx = FacesContext.getCurrentInstance();
         String contentType = "text/html;charset=utf-8";
         HttpServletResponse response = (HttpServletResponse) ctx
                 .getExternalContext().getResponse();
         response.setContentType(contentType);
         ServletOutputStream out = response.getOutputStream();
         StringBuffer buf = new StringBuffer();
buf.append("<script type=\"text/javascript\">\n");
         buf.append("<!--\n");
        // 弹出模式窗口
         buf.append("var rtn=window.showModalDialog('");
.....