Question

在Java中怎么获得网页状态码，比如：404等

Answer 1

StatusCode 似乎 Servelt API中，无论是 Filter Wrapper Reponse，都没有提供 get的方法。
以下是一个从网上找到的解决方案。

1.先实现一个对Response的包装器：
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;
}

}

2， 然后实现一个Filter来替换原始的HttpServletResponse，这样你就可以在Filter里面取到statusCode了

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 在这儿你就得到状态码了。
}

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

public void destroy() {
// empty
}

}