Spring - 从过滤器返回 JSON 格式的错误消息

Question

我正在开发一个 Spring Boot REST 应用程序。

我注册了一个自定义 AuthenticationEntryPoint，如果用户不提供凭据，它会返回“401 Unauthorized”错误。

@Component
public class CustomAuthenticationEntryPoint implements AuthenticationEntryPoint {

    @Override
    public void commence(HttpServletRequest request, HttpServletResponse response, AuthenticationException authException) throws IOException {
        response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Unauthorized");
    }
}

这很好用，并返回 JSON 格式的 DefaultErrorAttributes，如下所示：

{
  "timestamp": 1465230610451,
  "status": 401,
  "error": "Unauthorized",
  "exception": "org.springframework.security.authentication.BadCredentialsException",
  "message": "Unauthorized",
  "path": "/webapp/login"
}

现在我已经使用以下doFilter() 覆盖向应用程序添加了Filter：

@ Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)throws IOException, ServletException {
    try {
        // Here be some code that fails.
    } catch (Exception e) {
        HttpServletResponse httpServletResponse = (HttpServletResponse) response;
        httpServletResponse.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Unauthorized");
    }

    chain.doFilter(request, response);
}

但是，此代码不是上面显示的 JSON 格式的 DefaultErrorAttributes，而是返回默认的 Tomcat“错误报告”HTML 页面。

为什么会发生这种情况？在这两种情况下使两个错误消息保持一致（JSON 格式）的最佳方法是什么？

Answer 1

原文链接http://teknosrc.com/java-break-filter-chain-return-custom-pojo-response-servlet/

public class TestFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,ServletException {

        if(ANY CONDITION){
            //ANY POJO CLASS
            // ErrorResponse is a public return object that you define yourself
            ErrorResponse errorResponse = new ErrorResponse();
            errorResponse.setCode(401);
            errorResponse.setMessage("Unauthorized Access");
   
            byte[] responseToSend = restResponseBytes(errorResponse);
            ((HttpServletResponse) response).setHeader("Content-Type", "application/json");
            ((HttpServletResponse) response).setStatus(401);
            response.getOutputStream().write(responseToSend);
            return;
        }

        //ANY OTHER BUSINESS LOGIC
        chain.doFilter(request, response);
    }

    @Override
    public void destroy() {

    }

    private byte[] restResponseBytes(ErrorResponse eErrorResponse) throws IOException {
        String serialized = new ObjectMapper().writeValueAsString(eErrorResponse);
        return serialized.getBytes();
    }  
}