如何从ServletFilter中的ServletResponse中获取HTTP状态代码？

问题描述：

我正在尝试报告从我的webapp返回的每个HTTP状态代码。但是，状态代码似乎无法通过ServletResponse访问，或者即使我将其转换为HttpServletResponse也是如此。有没有办法在ServletFilter中访问这个值？

I'm trying to report on every HTTP status code returned from my webapp. However the status code does not appear to be accessible via the ServletResponse, or even if I cast it to a HttpServletResponse. Is there a way to get access to this value within a ServletFilter?

答

首先，您需要将状态代码保存在方便的地方。最好用您的实现包装响应并将其保留在那里：

First, you need to save the status code in an accessible place. The best to wrap the response with your implementation and keep it there:

public class StatusExposingServletResponse extends HttpServletResponseWrapper {

    private int httpStatus;

    public StatusExposingServletResponse(HttpServletResponse response) {
        super(response);
    }

    @Override
    public void sendError(int sc) throws IOException {
        httpStatus = sc;
        super.sendError(sc);
    }

    @Override
    public void sendError(int sc, String msg) throws IOException {
        httpStatus = sc;
        super.sendError(sc, msg);
    }


    @Override
    public void setStatus(int sc) {
        httpStatus = sc;
        super.setStatus(sc);
    }

    public int getStatus() {
        return httpStatus;
    }

}

为了使用这个包装器，你需要添加一个servlet过滤器，你可以做你的报告：

In order to use this wrapper, you need to add a servlet filter, were you can do your reporting:

public class StatusReportingFilter implements Filter {

    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        StatusExposingServletResponse response = new StatusExposingServletResponse((HttpServletResponse)res);
        chain.doFilter(req, response);
        int status = response.getStatus();
        // report
    }

    public void init(FilterConfig config) throws ServletException {
        //empty
    }

    public void destroy() {
        // empty
    }

}

如何从ServletFilter中的ServletResponse中获取HTTP状态代码？

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