从 SQL 数据库中检索数据并使用动态创建的标签显示 Ping 结果

Question

我需要在动态创建的标签中显示我的 SQL 数据库中的两个字段。因此，对于数据库中的每个条目，它都需要将其显示在彼此下方标签中的主要 window 上。但它没有显示标签中的信息。

所以这就是需要发生的事情。

用户将信息保存到 SQL 数据库（主机名、IP 地址和设备）
在主屏幕上（windows）然后需要这样显示：

服务器 1 192.168.x.x“Ping 结果”

这是我目前拥有的代码（这还不包括 ping 结果标签）

private void AddDynamicLabels()
{
    string ConString = @"Data Source=PC\SQL;Initial Catalog=PingMonitorDB;Integrated Security=True";
    SqlConnection con = new SqlConnection(ConString);
    string CmdString = "SELECT host, ip FROM addhosts";
    SqlCommand cmd = new SqlCommand(CmdString, con);
    con.Open();
    SqlDataReader reader = cmd.ExecuteReader();
    while (reader.Read())
    {
        Label lbl = new Label();
        lbl.Visible = true;
        lbl.Text = reader["host" + "ip" + "   "].ToString();
        lbl.BackColor = System.Drawing.Color.Orange;
        this.Controls.Add(lbl);
    }
    con.Close();
}

因此，对于添加的每个条目，理论上应该如下所示：

 Server 1  192.168.x.x   "ping reply"
 Server 2  192.168.x.x   "ping reply"
 Server 3  192.168.x.x   "ping reply"
 ....
 etc

编辑

private async void frmMainWindow_Load(object sender, EventArgs e)
{
    SqlConnection cnn = new SqlConnection(@"Data Source=PC\SQL;Initial Catalog=PingMonitorDB;Integrated Security=True");
    cnn.Open();
    SqlCommand cmd = new SqlCommand();
    cmd.Connection = cnn;
    SqlDataAdapter dp = new SqlDataAdapter();

    DataTable dtTable = new DataTable();
    cmd.CommandText = "SELECT host, ip FROM addhosts";
    cmd.CommandType = CommandType.Text;
    dp.SelectCommand = cmd;
    dp.Fill(dtTable);
    cnn.Close();
    for (int i = 0; i < dtTable.Rows.Count; i++)
    {
        ipAddress.Add("ip");
        Label lbl = new Label();
        lbl.Visible = true;
        lbl.AutoSize = true;
        lbl.Font = new Font("Arial", 12, FontStyle.Bold);
        lbl.Text = dtTable.Rows[i]["host"].ToString() + "  " + dtTable.Rows[i]["ip"].ToString();
        lbl.BackColor = System.Drawing.Color.Orange;
        this.Controls.Add(lbl);
        flowLayoutPanel1.Controls.Add(lbl);

        var controls = new Control[] { /* a list of existing Controls */ };
        // The Addresses count must match the Controls'
        var addresses = ["0.0.0.0"]; => Not sure what to do here though?
        var massPing = new MassPing();
        await massPing.PingAll(addresses, controls, 2000);
    }
}

MassPing Class 显示在上一个问题中：

Answer 1

使用此代码：

SqlConnection cnn = new SqlConnection("....");
cnn.Open();
SqlCommand cmd = new SqlCommand();
cmd.Connection = cnn;
SqlDataAdapter dp = new SqlDataAdapter();

cmd.CommandText = "SELECT host, ip FROM addhosts";
cmd.CommandType = CommandType.Text;
dp.SelectCommand = cmd;
dp.Fill(dtTable);
cnn.Close();
for (int i = 0; i < dtTable.Rows.Count; i++)
{
    Label lbl = new Label();
    lbl.Visible = true;
    lbl.Text = dtTable.Rows[i]["host"].ToString() + dtTable.Rows[i]["ip"].ToString();
    lbl.BackColor = System.Drawing.Color.Orange;
    this.Controls.Add(lbl);
}

Answer 2

我已经修改了 MassPing Class 和 通用化 过程，以不同的方式创建了一个 Progress<T> 委托，在MassPing class.
SetPingProgressDelegate() 方法在调用 MassPing.PinAll() 方法之前创建委托。

在您的代码中，每次读取新记录并以相同方式添加新控件时，您都会调用 PingAll() 方法。
这当然行不通：您需要事先创建一个 IP 地址列表和一个控件列表，然后将创建的控件添加到 FlowLayoutPanel 并将地址列表传递给 MassPing 并等待其结果。

修改数据库访问过程以处理所有创建的一次性对象。
也在等待 SqlClient 提供的 async 方法。

将调用代码移至 Shown 事件处理程序（而不是 Load）。

private async void frmMainWindow_Shown(object sender, EventArgs e)
{
    var ipAddresses = new List<string>();
    var ipControls = new List<Control>();
    var font = new Font("Segoe UI", 20, FontStyle.Regular, GraphicsUnit.Pixel);

    string sql = "SELECT [host], [ip] FROM addhosts";
    string connString = @"Data Source=PC\SQL;Initial Catalog=PingMonitorDB;Integrated Security=True";

    using (var conn = new SqlConnection(connString))
    using (var cmd = new SqlCommand(sql, conn)) {
        await conn.OpenAsync();
        using (var reader = await cmd.ExecuteReaderAsync()) {
            int ipCount = 0;
            while (await reader.ReadAsync()) {
                var lbl = new Label() {
                    AutoSize = false,
                    BackColor = Color.LightGray,
                    ForeColor = Color.Black,
                    Font = font,
                    Name = $"lblAddress{ipCount}",
                    Size = new Size(flowLayoutPanel1.ClientSize.Width, font.Height + 4),
                    Text = $"{reader["host"]} {reader["ip"]} "
                };
                ipAddresses.Add(reader["ip"].ToString());
                ipControls.Add(lbl);
            }
        }
    }

    // If the Reader returned some results, add the Control to a FlowLayoutPanel
    // and pass the list of addresses to MassPing, plus the Progress<T> delegate
    if (ipAddresses.Count > 0) {
        flowLayoutPanel1.Controls.AddRange(ipControls.ToArray());
        var massPing = new MassPing();
        var progress = SetPingProgressDelegate(ipControls);
        await massPing.PingAll(ipAddresses.ToArray(), progress, 2500);
    }
}

专业IProgress<T>委托:
在同一个表单中添加此方法。或者将访问修饰符更改为 public 并将其添加到表单可以到达的 internal class。
更改颜色以适合您设计的 UI。

private IProgress<(int, object)> SetPingProgressDelegate(List<Control> uiControls)
{
    var controls = uiControls;
    var obj = new object();

    // Create a Progress<T> delegate to receive status updates  
    // Each Task reports back here. This code is executed in the UI Thread
    var progress = new Progress<(int seq, object reply)>(report => {
        lock (obj) { // Not strictly necessary. Test without it
            var status = IPStatus.Unknown;
            var color = Color.LightGray;
            if (report.reply is PingReply pr) {
                status = pr.Status;
                color = status is IPStatus.Success
                    ? pr.RoundtripTime > 10 ? Color.Yellow : Color.LightGreen
                    : Color.OrangeRed;
            }
            else if (report.reply is SocketError socErr) {
                if (socErr == SocketError.HostNotFound) {
                    status = IPStatus.DestinationHostUnreachable;
                    color = Color.Red;
                }
                else {
                    // Something else went wrong. Handle if you care.
                    status = IPStatus.Unknown;
                }
            }
            controls[report.seq].BackColor = color;
            controls[report.seq].Text += status.ToString();
        }
    });
    return progress;
}

修改MassPingclass:
接收 IP 地址列表（作为字符串）并初始化相应数量的 PingAsync() 任务。每个 PingAsync() 任务都会报告其结果，包括创建任务时生成的序列指示符。请参阅注释：

using System.Collections.Generic;
using System.Net.NetworkInformation;
using System.Net.Sockets;
using System.Threading.Tasks;

public class MassPing
{
    public async Task PingAll(string[] addresses, IProgress<(int seq, object reply)> progress,  uint timeout = 2000)
    {
        var tasks = new List<Task>();

        // Add all tasks
        for (int seq = 0; seq < addresses.Length; seq++) {
            tasks.Add(PingAsync(addresses[seq], (int)timeout, seq, progress));
        }
        await Task.WhenAll(tasks);
    }

    private async Task PingAsync(string ipAddress, int timeOut, int sequence, IProgress<(int seq, object reply)> progress)
    {
        var buffer = new byte[32];
        var ping = new Ping();

        try {
            var options = new PingOptions(64, true);
            PingReply reply = await ping.SendPingAsync(ipAddress, timeOut, buffer, options);
            progress.Report((sequence, reply));
        }
        catch (PingException pex) {
            if (pex.InnerException is SocketException socEx) {
                progress.Report((sequence, socEx.SocketErrorCode));
            }
            else {
                // InnerException should be a SocketException. If not, something went bad
                // Handle specific cases if this kind of reporting is needed
                progress.Report((sequence, SocketError.SocketError));
            }
        }
        catch (InvalidOperationException) {
            // Overlapping sequence. Should never happen
            progress.Report((sequence, SocketError.AlreadyInProgress));
        }
        finally {
            ping.Dispose();
        }
    }
}

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