java - response.sendError 使用自定义过滤器抛出异常

Question

我有一份注册表单，提交后我需要:创建一个新用户并登录该用户。

如果用户名已在数据库中，我需要返回 409 并包含错误消息。

我创建了一个设置 HttpStatus 的自定义过滤器

public class UserSignupFilter implements Filter {
...
    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) res;

        if (userSignup(request)) {
            if (userAlreadyExists(request)){
                logger.info("Didnt create user since: "+e.getMessage());
                response.sendError(HttpStatus.CONFLICT.value());
            } else {
                createUser(request);
            }
        }           
        chain.doFilter(request, response);
    }
}

问题是我有时会遇到:

java.lang.IllegalStateException: Cannot call sendError() after the response has been committed.  

有更好的方法吗？我正在以编程方式设置安全性(Spring Security V 3.2)，如何使用 ExceptionTranslationFilter？

Answer 1

我认为你不应该打电话:

chain.doFilter(request, response);

如果您只想发回错误代码。只需调用 return

logger.info("Didnt create user since: "+e.getMessage());
response.sendError(HttpStatus.CONFLICT.value());
return;