Question

有一些很好的库，比如this from Apache，但这对我来说有点太复杂了。我需要的是获得HTTP延迟的最佳估计（与服务器连接所需的时间，无论传输速度如何）。

我尝试了来自this answer的HTTP连接代码：

  private void doPing() {
    //Remember time before connection
    long millis = System.currentTimeMillis();
    try (BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream(), "UTF-8"))) {
      //We don't need any data
      reader.close();
      //Times is the array where we store our results
      times.add((int)(System.currentTimeMillis()-millis));
      //I see lot's of these in console, so it's probably working
      System.out.println("Request done...");
    }
    //If internet is dead, does it throw exception?
    catch(Exception e) {
      times.add(-1);
    }
  }

问题是我不太确定我在测量什么。循环使用这些数据给了我这样的结果：

Testing connection to http://www.seznam.cz
      Threads: 5
      Loops per thread: 50
Given up waiting for results.
Average time to connection: 53.8 [ms]
Failures: 0.0%

Testing connection to http://www.seznam.cz
      Threads: 5
      Loops per thread: 100
Average time to connection: 43.58 [ms]
Failures: 0.0%

Testing connection to http://www.seznam.cz
      Threads: 5
      Loops per thread: 400
Average time to connection: 30.145 [ms]
Failures: 0.0%

Testing connection to http://www.stackoverflow.com
      Threads: 5
      Loops per thread: 30
Given up waiting for results.
Average time to connection: 4006.1111111111113 [ms]
Failures: 0.0%

Testing connection to http://www.stackoverflow.com
      Threads: 5
      Loops per thread: 80
Given up waiting for results.
Average time to connection: 2098.695652173913 [ms]
Failures: 0.0%

Testing connection to http://www.stackoverflow.com
      Threads: 5
      Loops per thread: 200
Given up waiting for results.
Average time to connection: 0.0 [ms]
//Whoops, connection dropped again
Failures: 100.0%

//Some random invalid url
Testing connection to http://www.sdsfdser.tk/
      Threads: 4
      Loops per thread: 20
Average time to connection: 0.0 [ms]
Failures: 100.0%

不仅如此，我不确定我是否计算了我想要的东西（尽管它反映了我的经验），我也不确定在非标准情况下会发生什么。

网址是否处理超时？
它会不会在超时时抛出异常？

虽然请记住这个项目应该简单轻便，你能否告诉我，我做得对吗？

Answer 1

我认为hailin建议您创建一个原始Socket并将其连接到服务器而不是使用URLConnection。我试过了两个，而且你的版本延迟得多了很多。我认为打开一个URLConnection必须在后台做一些额外的事情，虽然我不确定是什么。

无论如何，这是使用Socket的版本（根据需要添加异常处理）：

Socket s = new Socket();
SocketAddress a = new InetSocketAddress("www.google.com", 80);
int timeoutMillis = 2000;
long start = System.currentTimeMillis();
try {
    s.connect(a, timeoutMillis);
} catch (SocketTimeoutException e) {
    // timeout
} catch (IOException e) {
    // some other exception
}
long stop = System.currentTimeMillis();
times.add(stop - start);
try {
    s.close();
} catch (IOException e) {
    // closing failed
}

这解析了主机名（示例中为www.google.com），在端口80上建立TCP连接，并将其花费的毫秒数添加到times。 ~~如果您不想在那里进行DNS解析，可以在启动计时器之前使用InetAddress创建InetAddress.getByName("hostname")并将其传递给InetSocketAddress构造函数。~~

编辑：InetSocketAddress的构造函数也会立即解析主机名，因此从已解析的IP地址构建它不应该有所作为。

测试HTTP延迟的简短代码？

1 个答案: