了HTTPClient每次都返回相同的字符串 [英] HTTPClient every time returns the same string

问题描述

能有一个人让我明白为什么我的代码每次都返回相同的字符串？

Could some one make me clear why my code returns the same string every time?

public MainPage()
{
    this.InitializeComponent();

    DispatcherTimer timer = new DispatcherTimer();
    timer.Interval = TimeSpan.FromSeconds(5);
    timer.Tick += OnTimerTick;
    timer.Start();
}

private void OnTimerTick(object sender, object e)
{
    getData();
    HubText.Text = dumpstr;
}

private async void getData()
{
    // Create an HttpClient instance
    HttpClient client = new HttpClient();
    var uri = new Uri("http://192.168.4.160:8081/v");
    try
    {
        // Send a request asynchronously continue when complete
        HttpResponseMessage response = await client.GetAsync(uri);
        // Check that response was successful or throw exception
        response.EnsureSuccessStatusCode();
        // Read response asynchronously
        dumpstr = await response.Content.ReadAsStringAsync();
    }
    catch (Exception e)
    {
        //throw;
    }
}
string dumpstr;

所以，每隔5秒钟，我得到了我在第一个请求得到了相同的字符串。
我在做什么错了？

So every 5 seconds I get the same string that I got in my first request. What am I doing wrong?

推荐答案

这是因为你在做一个GET相同的URL。根据HTTP语义，该值应该是一个合理的时间内是相同的，所以操作系统缓存为您的响应。

It's because you're doing a GET to the same URL. According to the HTTP semantics, the value should be the same within a reasonable timeframe, so the OS is caching the response for you.

您可以通过任何绕过缓存这些方法：

You can bypass the cache by any of these methods:

• 使用POST请求


• 添加查询字符串参数是不同的。每个呼叫。


• 指定（在服务器上）禁止或限制缓存响应头允许的。

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