C#多线程TPL常见操作误区与异常处理

public async Task<string> GetAsync()
{
    return await Task.Run<string>(() => 
    {
        using (WebClient client = new WebClient())
        {
            // 这里使用的是同步方法，所以该异步方法没有意义
            return client.DownloadString("http://www.baidu.com");
        }
    });
}

private void button1_Click(object sender, EventArgs e)
{
    try
    {
        HttpClient hc = new HttpClient();
        // 存在的url地址
        string url1 = "http://www.baidu.com";
        // 不存在的url地址
        string url2 = "http://www.121qwqwqw.com";
        string url3 = "http://www.7546456dfsdf.com";
        var task1 = hc.GetStringAsync(url1);
        var task2 = hc.GetStringAsync(url2);
        var task3 = hc.GetStringAsync(url3);
        // 并行执行三个任务
        Task.WaitAll(task1, task2, task3);
        MessageBox.Show("下载成功");
       
    }
    catch (AggregateException ae)
    {
        // 循环遍历输出异常信息
        foreach (var item in ae.InnerExceptions)
        {
            MessageBox.Show(item.Message);
        }
    }
}