在java过滤器中计算响应时间

Question

我不知道 java 过滤器中 doFilter() 方法的生命周期。 我想知道我是否要在方法开始时在请求中设置开始时间，有没有办法或地方在方法中设置停止时间，这会给我从请求开始到的总经过时间给出答复的时间？ 我已经看到了一个带有 finally 块的 doFilter() 方法，我想知道在响应中设置停止时间是否合适？

Answer 1

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

public class ResponseTimerFilter implements Filter {
  protected FilterConfig config;

  public void init(FilterConfig config) throws ServletException {
    this.config = config;
  }

  public void destroy() {
  }

  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
      throws ServletException, IOException {
    long startTime = System.currentTimeMillis();
    chain.doFilter(request, response);
    long elapsed = System.currentTimeMillis() - startTime;
    String name = "servlet";
    if (request instanceof HttpServletRequest) {
      name = ((HttpServletRequest) request).getRequestURI();
    }

    config.getServletContext().log(name + " took " + elapsed + " ms");
  }
}

web.xml

<filter>
  <filter-name>Timing Filter</filter-name>
  <filter-class>com.omh.filters.ResponseTimerFilter</filter-class>
</filter>

<filter-mapping>
  <filter-name>Timing Filter</filter-name>
  <url-pattern>/*</url-pattern>
</filter-mapping>