javax.imageio.IIOException: Cant create output stream! 解决方法 验证码出不来

百度其它帖子说设置temp权限，但我这边还是不行。

通过下面关闭缓存可以解决，如果不关就会向tomcat/temp/ 目录下写东西但好像写不了就会报错

/*** 本系统所有的验证码均采用此方法* @param vcodeLen* @param width* @param height* @param cpachaType:用来区别验证码的类型，传入字符串* @param request* @param response*/
@RequestMapping(value="/get_cpacha",method=RequestMethod.GET)
public void generateCpacha(@RequestParam(name="vl",required=false,defaultValue="4") Integer vcodeLen,@RequestParam(name="w",required=false,defaultValue="100") Integer width,@RequestParam(name="h",required=false,defaultValue="30") Integer height,@RequestParam(name="type",required=true,defaultValue="loginCpacha") String cpachaType,HttpServletRequest request,HttpServletResponse response){CpachaUtil cpachaUtil = new CpachaUtil(vcodeLen, width, height);String generatorVCode = cpachaUtil.generatorVCode();request.getSession().setAttribute(cpachaType, generatorVCode);BufferedImage generatorRotateVCodeImage = cpachaUtil.generatorRotateVCodeImage(generatorVCode, true);try {
　　　　ImageIO.setUseCache(false);ImageIO.write(generatorRotateVCodeImage, "gif", response.getOutputStream());} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}
}