Question

我编写了扫描QR码的代码。但是，我想通过从文本框或任何其他来源获取输入来生成QR码。我一直在寻找它，但似乎没有这样的选择。我必须编写本机代码，我遇到问题。请指导我。我做到了 -

    final TextField text = new TextField();
    final SpanButton qrGen = new SpanButton("Generate QR");
    qrGen.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent evt) {
            System.out.println("Comes here.....");
            MyNative n = (MyNative)NativeLookup.create(MyNative.class) ;
            if(n != null && n.isSupported()) {
                String path = (String) evt.getSource();
                System.out.println("Comes here2.....");
                InputStream is = null;
                try {
                    is = com.codename1.io.FileSystemStorage.getInstance().openInputStream(path);
                    System.out.println("Comes here3.....");
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                Image i = null;
                try {
                    i = Image.createImage(is);
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }//(n.genQR(text.getText()));
                ImageViewer iv = new ImageViewer(i);
                g.removeAll();
                g.addComponent(iv);
                f.addComponent(BorderLayout.SOUTH, g);
                f.show();
            }
        }
    });
    g.addComponent(text);
    g.addComponent(qrGen);
    f.addComponent(BorderLayout.SOUTH, g);
    f.show();

MyNative对象保持为null，永远不会到达内部块。这是我的原生实现 -

package com.codename1;

import com.google.zxing.QRCodeWriter;

public class MyNativeImpl implements MyNative {
public Object genQR(String param) {
    ImageView imageView = (ImageView) findViewById(R.id.qrCode);
    try {
        return encodeAsBitmap(STR);
    } catch (WriterException e) {
        e.printStackTrace();
    }
}

Bitmap encodeAsBitmap(String str) throws WriterException {
    BitMatrix result;
    try {
        result = new QRCodeWriter().encode(str, 
            BarcodeFormat.QR_CODE, WIDTH, WIDTH, null);
    } catch (IllegalArgumentException iae) {
        // Unsupported format
        return null;
    }
    int w = result.getWidth();
    int h = result.getHeight();
    int[] pixels = new int[w * h];
    for (int y = 0; y < h; y++) {
        int offset = y * w;
        for (int x = 0; x < w; x++) {
            pixels[offset + x] = result.get(x, y) ? BLACK : WHITE;
        }
    }
    Bitmap bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
    bitmap.setPixels(pixels, 0, width, 0, 0, w, h);
    return bitmap;
}

public boolean isSupported() {
    return true;
}

}

Answer 1

本机界面仅适用于设备本身。

看起来你的本地接口是有效的，因为你从界面返回一个非法的Object。您应该返回byte[]。

原生参数/返回类型仅限于更好的语言互操作性。

Answer 2

如果您的应用将在线投放，我建议您使用Google QR code api。它为您生成QR，返回图像并且不需要编写本机代码。 Google QR图片示例here。否则，您应该使用真实设备调试您的应用程序，因为除非您编写java本机代码，否则本机界面不会在模拟器上工作。

下面的代码应该可以帮助您使用本机接口，而不是在stackoverflow上测试和编写：

Android MyNativeImpl.java：

package com.yourpackage.anything;

import com.google.zxing.QRCodeWriter;

public class MyNativeImpl {
public byte[] generateQRFromString(String str) throws WriterException {
    BitMatrix result;
    try {
        result = new QRCodeWriter().encode(str,
                BarcodeFormat.QR_CODE, WIDTH, WIDTH, null);
    } catch (IllegalArgumentException iae) {
        // Unsupported format
        return null;
    }
    int w = result.getWidth();
    int h = result.getHeight();
    int[] pixels = new int[w * h];
    for (int y = 0; y < h; y++) {
        int offset = y * w;
        for (int x = 0; x < w; x++) {
            pixels[offset + x] = result.get(x, y) ? BLACK : WHITE;
        }
    }
    Bitmap bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
    bitmap.setPixels(pixels, 0, width, 0, 0, w, h);

    ByteArrayOutputStream stream = new ByteArrayOutputStream();
    bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream);
    byte[] byteArray = stream.toByteArray();
    return byteArray;
}
}

<强> MyNative.java

package com.yourpackage.anything;

import com.codename1.system.NativeInterface;
public interface MyNative extends NativeInterface {
    public byte[] generateQRFromString(String str);
}

现在您可以将返回的字节[]转换为CN1代码中的图像。如果您不知道如何，请查看CN1 Javadoc或@Shai是否可以帮助您使用代码段。根据您尝试做的事情，您可以尝试以下方式：

    final TextField text = new TextField();
    final SpanButton qrGen = new SpanButton("Generate QR");
    qrGen.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent evt) {
            System.out.println("Comes here.....");
            MyNative n = (MyNative) NativeLookup.create(MyNative.class);
            if (n != null && n.isSupported()) {
                byte[] byteData = n.generateQRFromString("Hello world");
                if (byteData != null) {
                    Image img = Image.createImage(byteData, 0, byteData.length);
                    ImageViewer iv = new ImageViewer(img);
                    g.removeAll();
                    g.addComponent(iv);
                    f.addComponent(BorderLayout.SOUTH, g);
                    f.show();
                } else {
                    //print My native code returned no image
                }

            }
        }
    });
    g.addComponent(text);
    g.addComponent(qrGen);
    f.addComponent(BorderLayout.SOUTH, g);
    f.show();

以codenameone生成QR码

2 个答案: