如何从 Java 过滤器获取请求 URL？

Question

我正在尝试编写一个可以检索请求 URL 的过滤器，但我不知道该怎么做。

这是我目前所拥有的：

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

public class MyFilter implements Filter {
    public void init(FilterConfig config) throws ServletException { }

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

        String url = ((HttpServletRequest) request).getPathTranslated();
        System.out.println("Url: " + url);
    }

    public void destroy() { }
}

当我点击服务器上的一个页面时，我看到的唯一输出是“Url: null”。

从过滤器中的给定 ServletRequest 对象获取请求的 URL 的正确方法是什么？

Answer 1

如果你使用Spring，你可以使用OncePerRequestFilter或其他。

import org.springframework.web.filter.OncePerRequestFilter;
import org.springframework.stereotype.Component;

@Component
public class MyFilter extends OncePerRequestFilter {
    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
         String url = request.getRequestURL();
         filterChain.doFilter(request, response);
    }

}

Answer 2

以another answer on this page 为基础，

public static String getCurrentUrlFromRequest(ServletRequest request)
{
   if (! (request instanceof HttpServletRequest))
       return null;

   return getCurrentUrlFromRequest((HttpServletRequest)request);
}

public static String getCurrentUrlFromRequest(HttpServletRequest request)
{
    StringBuffer requestURL = request.getRequestURL();
    String queryString = request.getQueryString();

    if (queryString == null)
        return requestURL.toString();

    return requestURL.append('?').append(queryString).toString();
}

Answer 3

这就是你要找的吗？

if (request instanceof HttpServletRequest) {
 String url = ((HttpServletRequest)request).getRequestURL().toString();
 String queryString = ((HttpServletRequest)request).getQueryString();
}

重建：

System.out.println(url + "?" + queryString);

HttpServletRequest.getRequestURL() 和 HttpServletRequest.getQueryString() 的信息。

Answer 4

request.getRequestURL();   

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