如何使用 .NET MAUI 创建桌面条形码应用程序（扫描器/生成器）

接下来，实现用户点击按钮时的逻辑。 在用户界面中，扫描按钮附加了一个OnScanButtonClicked事件处理程序。

PickPhotoAsync首先用于让用户选择要上传的条形码，然后使用OpenReadAsync访问文件流。 使用CopyToAsync立即将图像数据复制到MemoryStream中。 这样就可以同时使用数据在屏幕上显示图像，并让Read方法扫描条形码。

最后，如果检测到有效的条形码，则会在用户界面中显示条形码值；如果未在图像中找到条形码，则会显示一条红色消息。

using IronBarCode;

namespace MauiApp1
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
            // Your license key is set here
            IronBarCode.License.LicenseKey = "YOUR_KEY"
        }

        private async void OnScanButtonClicked(object sender, EventArgs e)
        {
            try
            {
                var fileResult = await MediaPicker.Default.PickPhotoAsync();

                if (fileResult != null)
                {
                    // 1. Copy the file content into a byte array or MemoryStream immediately
                    // This ensures we have the data in memory before the file closes
                    byte[] imageBytes;
                    using (var stream = await fileResult.OpenReadAsync())
                    using (var memoryStream = new MemoryStream())
                    {
                        await stream.CopyToAsync(memoryStream);
                        imageBytes = memoryStream.ToArray();
                    }

                    // 2. Set the Image Source for the UI
                    // We give the UI a FRESH stream from the bytes we just saved
                    ScannerImage.Source = ImageSource.FromStream(() => new MemoryStream(imageBytes));

                    // 3. Process the Barcode
                    // We give IronBarcode its OWN fresh stream from the same bytes
                    using (var processingStream = new MemoryStream(imageBytes))
                    {
                        // 4. Read the barcode with Read
                        var results = BarcodeReader.Read(processingStream);

                        // 5. Display barcode results
                        if (results != null && results.Count > 0)
                        {

                            // Successfully found barcode value
                            ResultLabel.Text = $"Success: {results[0].Value}";
                            ResultLabel.TextColor = Colors.Green;
                        }
                        else
                        {
                            // Image uploaded has no barcode or barcode value is not found
                            ResultLabel.Text = "No barcode detected.";
                            ResultLabel.TextColor = Colors.Red;
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                // Display any exception thrown in runtime
                ResultLabel.Text = $"Error: {ex.Message}";
                ResultLabel.TextColor = Colors.Red;
            }
        }
    }
}

using IronBarCode;

namespace MauiApp1
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
            // Your license key is set here
            IronBarCode.License.LicenseKey = "YOUR_KEY"
        }

        private async void OnScanButtonClicked(object sender, EventArgs e)
        {
            try
            {
                var fileResult = await MediaPicker.Default.PickPhotoAsync();

                if (fileResult != null)
                {
                    // 1. Copy the file content into a byte array or MemoryStream immediately
                    // This ensures we have the data in memory before the file closes
                    byte[] imageBytes;
                    using (var stream = await fileResult.OpenReadAsync())
                    using (var memoryStream = new MemoryStream())
                    {
                        await stream.CopyToAsync(memoryStream);
                        imageBytes = memoryStream.ToArray();
                    }

                    // 2. Set the Image Source for the UI
                    // We give the UI a FRESH stream from the bytes we just saved
                    ScannerImage.Source = ImageSource.FromStream(() => new MemoryStream(imageBytes));

                    // 3. Process the Barcode
                    // We give IronBarcode its OWN fresh stream from the same bytes
                    using (var processingStream = new MemoryStream(imageBytes))
                    {
                        // 4. Read the barcode with Read
                        var results = BarcodeReader.Read(processingStream);

                        // 5. Display barcode results
                        if (results != null && results.Count > 0)
                        {

                            // Successfully found barcode value
                            ResultLabel.Text = $"Success: {results[0].Value}";
                            ResultLabel.TextColor = Colors.Green;
                        }
                        else
                        {
                            // Image uploaded has no barcode or barcode value is not found
                            ResultLabel.Text = "No barcode detected.";
                            ResultLabel.TextColor = Colors.Red;
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                // Display any exception thrown in runtime
                ResultLabel.Text = $"Error: {ex.Message}";
                ResultLabel.TextColor = Colors.Red;
            }
        }
    }
}

输出结果包含找到的条形码值

如您所见，该应用程序显示了条形码结果和上传的条形码图像。

未找到条形码值

如您所见，当用户上传的图片不包含条形码时，会显示一条红色消息，提示"未找到条形码"。

接下来，实现按钮点击事件的逻辑。 UI 中的生成按钮附加了一个OnGenerateButtonClicked事件处理程序。

用户输入经过验证，以确保文本存在并且已选择类型，之后将选择映射到正确的BarcodeEncoding 。 BarcodeWriter.CreateBarcode用于生成图像、调整图像大小并将其转换为 JPEG 二进制数据。 然后使用MemoryStream将图像显示在屏幕上。

最后，使用File.WriteAllBytes将生成的条形码文件直接保存到用户的桌面，并更新状态标签以确认保存位置。

using IronBarCode;
using System.IO; // Required for saving files

namespace MauiApp1
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
            IronBarCode.License.LicenseKey = "YOUR-KEY";

            // Set default selection
            BarcodeTypePicker.SelectedIndex = 0;
        }

        private void OnGenerateButtonClicked(object sender, EventArgs e)
        {
            try
            {
                // 1. Get and Validate Input
                string text = BarcodeEntry.Text;

                if (string.IsNullOrWhiteSpace(text))
                {
                    StatusLabel.Text = "Error: Please enter text.";
                    StatusLabel.TextColor = Colors.Red;
                    return;
                }

                if (BarcodeTypePicker.SelectedIndex == -1)
                {
                    StatusLabel.Text = "Error: Please select a type.";
                    StatusLabel.TextColor = Colors.Red;
                    return;
                }

                // 2. Determine Encoding Type
                string selectedType = BarcodeTypePicker.SelectedItem.ToString();
                BarcodeEncoding encoding = BarcodeEncoding.QRCode;

                switch (selectedType)
                {
                    case "QRCode": encoding = BarcodeEncoding.QRCode; break;
                    case "Code128": encoding = BarcodeEncoding.Code128; break;
                    case "EAN13": encoding = BarcodeEncoding.EAN13; break;
                    case "Code39": encoding = BarcodeEncoding.Code39; break;
                    case "PDF417": encoding = BarcodeEncoding.PDF417; break;
                }

                // 3. Generate Barcode
                var barcode = BarcodeWriter.CreateBarcode(text, encoding);
                barcode.ResizeTo(400, 200); // Optional resizing

                // 4. Convert to Bytes (JPEG)
                var bytes = barcode.ToJpegBinaryData();

                // 5. Update UI
                GeneratedImage.Source = ImageSource.FromStream(() => new MemoryStream(bytes));

                // 6. Save to Desktop automatically
                string desktopPath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
                string fileName = $"barcode_{DateTime.Now:yyyyMMdd_HHmmss}.jpg";
                string fullPath = Path.Combine(desktopPath, fileName);

                File.WriteAllBytes(fullPath, bytes);

                // 7. Show Success Message
                StatusLabel.Text = $"Saved to Desktop:\n{fileName}";
                StatusLabel.TextColor = Colors.Green;
            }
            catch (Exception ex)
            {
                StatusLabel.Text = $"Error: {ex.Message}";
                StatusLabel.TextColor = Colors.Red;
            }
        }
    }
}

using IronBarCode;
using System.IO; // Required for saving files

namespace MauiApp1
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
            IronBarCode.License.LicenseKey = "YOUR-KEY";

            // Set default selection
            BarcodeTypePicker.SelectedIndex = 0;
        }

        private void OnGenerateButtonClicked(object sender, EventArgs e)
        {
            try
            {
                // 1. Get and Validate Input
                string text = BarcodeEntry.Text;

                if (string.IsNullOrWhiteSpace(text))
                {
                    StatusLabel.Text = "Error: Please enter text.";
                    StatusLabel.TextColor = Colors.Red;
                    return;
                }

                if (BarcodeTypePicker.SelectedIndex == -1)
                {
                    StatusLabel.Text = "Error: Please select a type.";
                    StatusLabel.TextColor = Colors.Red;
                    return;
                }

                // 2. Determine Encoding Type
                string selectedType = BarcodeTypePicker.SelectedItem.ToString();
                BarcodeEncoding encoding = BarcodeEncoding.QRCode;

                switch (selectedType)
                {
                    case "QRCode": encoding = BarcodeEncoding.QRCode; break;
                    case "Code128": encoding = BarcodeEncoding.Code128; break;
                    case "EAN13": encoding = BarcodeEncoding.EAN13; break;
                    case "Code39": encoding = BarcodeEncoding.Code39; break;
                    case "PDF417": encoding = BarcodeEncoding.PDF417; break;
                }

                // 3. Generate Barcode
                var barcode = BarcodeWriter.CreateBarcode(text, encoding);
                barcode.ResizeTo(400, 200); // Optional resizing

                // 4. Convert to Bytes (JPEG)
                var bytes = barcode.ToJpegBinaryData();

                // 5. Update UI
                GeneratedImage.Source = ImageSource.FromStream(() => new MemoryStream(bytes));

                // 6. Save to Desktop automatically
                string desktopPath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
                string fileName = $"barcode_{DateTime.Now:yyyyMMdd_HHmmss}.jpg";
                string fullPath = Path.Combine(desktopPath, fileName);

                File.WriteAllBytes(fullPath, bytes);

                // 7. Show Success Message
                StatusLabel.Text = $"Saved to Desktop:\n{fileName}";
                StatusLabel.TextColor = Colors.Green;
            }
            catch (Exception ex)
            {
                StatusLabel.Text = $"Error: {ex.Message}";
                StatusLabel.TextColor = Colors.Red;
            }
        }
    }
}

输出生成的条形码

如您所见，该应用程序会显示生成的条形码并将其保存到用户的桌面。

输出失败

某些条形码类型对输入值有限制和格式要求。 当条形码生成失败时，应用程序会显示 IronBarcode 异常，如上所示。 请参考相应的详细一维和二维条码格式说明，了解每种条码类型的格式要求。

要测试上述示例（桌面条形码扫描器和桌面条形码生成器），请下载此示例项目。