如何在 C# 的列表框中创建“日志记录功能”。从其他类获取信息

Question

我在将信息从其他类“传递”到程序的主窗体时遇到问题。它是一个客户端-服务器应用程序。我想在列表框中的服务器主窗体上创建一个“日志接口”（或类似的东西，并不重要......），例如当一个客户端连接到服务器时显示。所以在我的应用程序中，它涉及两个类：Datebase.cs 和 Form.cs。当来自 database.cs 的呼叫时，我应该使用自定义文本修改 listbox1.Text。我试过 Form1.listBox1.Items.Add(logon);但它失败了：/

Database.cs

// Other classes and methods...

public class Database
{
    public string logon;
    public string logoff; 

    // some methods

    internal bool Logon(string username,string password)
    {
        // blah blah...
                logon = DateTime.Now.ToString() + " - Username " + username + " just logged on";
                Form.listBox1.Items.Add(logon);
    }
    internal bool Logoff(string username)
    {
            // blah blah...
            logoff = DateTime.Now.ToString() + " - Username " + username + " just logged off";
            Form.listBox1.Items.Add(logoff);

    }
}

而另一个类只是一个带有 listBox1 的主窗体。它设置为公共的，它在同一个命名空间中，只是不同的类。

Form.cs（设计师部分）

partial class Form
{
    private System.ComponentModel.IContainer components = null;

    protected override void Dispose(bool disposing)
    {
        if (disposing && (components != null))
        {
            components.Dispose();
        }
        base.Dispose(disposing);
    }

    #region Windows Form Designer generated code

    private void InitializeComponent()
    {
        this.listBox1 = new System.Windows.Forms.ListBox();
        this.SuspendLayout();
        // 
        // listBox1
        // 
        this.listBox1.AllowDrop = true;
        this.listBox1.FormattingEnabled = true;
        this.listBox1.Items.AddRange(new object[] {
        "Blah blah...",
        "BLAH BLAH!"});
        this.listBox1.Location = new System.Drawing.Point(12, 78);
        this.listBox1.Name = "listBox1";
        this.listBox1.ScrollAlwaysVisible = true;
        this.listBox1.SelectionMode = System.Windows.Forms.SelectionMode.MultiSimple;
        this.listBox1.Size = new System.Drawing.Size(429, 329);
        this.listBox1.TabIndex = 1;
        // 
        // Form1
        // 
        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
        this.ClientSize = new System.Drawing.Size(532, 465);
        this.Controls.Add(this.listBox1);
        this.Name = "Form1";
        this.Text = "Form1";
        this.ResumeLayout(false);

    }

    #endregion

    public System.Windows.Forms.ListBox listBox1;

Answer 1

您需要将Form 实例传递给Database，或者最好不要从Database 类更新列表框。将更新 UI（本例中为列表框）的责任留给 Form。让Form读取Logon/Logoff函数的返回值，并相应更新Listbox。

private Database _database = new Database();

private void LogonButton_Click(object sender, EventeArgs e)
{
    var logonResult = _database.Logon("username", "password");
    if(logonResult) 
    {
        logon = DateTime.Now.ToString() + " - Username " + username + " just logged on";
        listBox1.Items.Add(logon);
    }
}

下面演示了将Form 实例传递给Database 的第一种方法进行比较（不推荐）：

public class Database
{
    ....
    public Form FormInstance;

    public Database(Form formInstance)
    {
        ....
        FormInstance = formInstance;
        ....
    }
    ....
    internal bool Logon(string username,string password)
    {
        // blah blah...
        logon = DateTime.Now.ToString() + " - Username " + username + " just logged on";
        FormInstance.listBox1.Items.Add(logon);
    }
    .....
}

//in Form, when creating Database instance pass current Form instance as parameter
private Database _database;
public Form()
{
    ....
    _database = new Database(this);
    ....
}