使用Filter计算请求耗时

有时为了更详细的检测web系统性能，需要计算每次请求到响应所耗费的时间，然后看看哪些请求耗时较多，从而有针对性的进行优化操作，此时可以使用Filter过滤器自己实现一个请求响应耗时计算的功能。每个请求在到达目标资源之前都会被Filter过滤器拦截，我们可以在请求到达之前获取系统当前的时间，每个响应也会先被Filter过滤器拦截，我们在此时也获取一下系统的当前时间，之后将两次时间作比较就能计算出这次请求响应所耗费的时间了。

创建一个Filter过滤器

package com.monkey1024.filter;

import javax.servlet.*;

import javax.servlet.annotation.WebFilter;

import javax.servlet.http.HttpServletRequest;

import java.io.IOException;

import java.time.Duration;

import java.time.LocalTime;

@WebFilter(filterName = "TimeFilter",urlPatterns = "/*")

public class TimeFilter implements Filter {

public void destroy() {

}

public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {

HttpServletRequest request = (HttpServletRequest) req;

//请求时的系统时间

LocalTime time1 = LocalTime.now();

chain.doFilter(req, resp);

//响应时的系统时间

LocalTime time2 = LocalTime.now();

//计算请求响应耗时

Duration total = Duration.between(time1, time2);

System.out.println(request.getRequestURI() + "耗时：" + total.toMillis());

}

public void init(FilterConfig config) throws ServletException {

}

}

通过上面的Filter过滤器就可以计算每次请求响应的耗时了，并且还可以查看到请求的目标资源，从而有针对性的做优化处理。

创建一个用于测试的Servlet：

package com.monkey1024.servlet;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

@WebServlet(name = "TestServlet",urlPatterns = {"/test"})

public class TestServlet extends HttpServlet {

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

//为了查看效果，所以睡眠3秒

try {

Thread.sleep(3000);

} catch (InterruptedException e) {

e.printStackTrace();

}

}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

doPost(request, response);

}

}