java获取当前线程的HttpServletRequest

在Java中，可以通过ThreadLocal类来实现在多线程环境下获取当前线程的HttpServletRequest对象。具体实现方法如下：

public class RequestHolder {
    private static final ThreadLocal<HttpServletRequest> REQUEST_HOLDER = new ThreadLocal<>();

    public static void add(HttpServletRequest request) {
        REQUEST_HOLDER.set(request);
    }

    public static HttpServletRequest getCurrentRequest() {
        return REQUEST_HOLDER.get();
    }

    public static void remove() {
        REQUEST_HOLDER.remove();
    }
}

在过滤器中，可以将HttpServletRequest对象存储到ThreadLocal中，然后在需要使用HttpServletRequest对象的地方，通过RequestHolder.getCurrentRequest()方法获取即可。具体实现方法如下：

public class RequestFilter implements Filter {
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        RequestHolder.add(request);
        try {
            filterChain.doFilter(servletRequest, servletResponse);
        } finally {
            RequestHolder.remove();
        }
    }
}