//要转换的地址或字符串,可以是中文
public void createQRImage(String url)
{
 try
 {
 //判断URL合法性
 if (url == null || "".equals(url) || url.length() < 1)
 {
  return;
 }
 Hashtable<EncodeHintType, String> hints = new Hashtable<EncodeHintType, String>();
 hints.put(EncodeHintType.CHARACTER_SET, "utf-8");
 //图像数据转换，使用了矩阵转换
 BitMatrix bitMatrix = new QRCodeWriter().encode(url, BarcodeFormat.QR_CODE, QR_WIDTH, QR_HEIGHT, hints);
 int[] pixels = new int[QR_WIDTH * QR_HEIGHT];
 //下面这里按照二维码的算法，逐个生成二维码的图片，
 //两个for循环是图片横列扫描的结果
 for (int y = 0; y < QR_HEIGHT; y++)
 {
  for (int x = 0; x < QR_WIDTH; x++)
  {
  if (bitMatrix.get(x, y))
  {
   pixels[y * QR_WIDTH + x] = 0xff000000;
  }
  else
  {
   pixels[y * QR_WIDTH + x] = 0xffffffff;
  }
  }
 }
 //生成二维码图片的格式，使用ARGB_8888
 Bitmap bitmap = Bitmap.createBitmap(QR_WIDTH, QR_HEIGHT, Bitmap.Config.ARGB_8888);
 bitmap.setPixels(pixels, 0, QR_WIDTH, 0, 0, QR_WIDTH, QR_HEIGHT);
 //显示到一个ImageView上面
 sweepIV.setImageBitmap(bitmap);
 }
 catch (WriterException e)
 {
 e.printStackTrace();
 }
}

private void restartPreviewAndDecode() {
 if (state == State.SUCCESS) {
 state = State.PREVIEW;
 CameraManager.get().requestPreviewFrame(decodeThread.getHandler(), R.id.decode);
 CameraManager.get().requestAutoFocus(this, R.id.auto_focus);
 activity.drawViewfinder();
 }
}

public void handleMessage(Message message) {
 switch (message.what) {
 case R.id.auto_focus:
 //Log.d(TAG, "Got auto-focus message");
 // When one auto focus pass finishes, start another. This is the closest thing to
 // continuous AF. It does seem to hunt a bit, but I'm not sure what else to do.
 if (state == State.PREVIEW) {
  CameraManager.get().requestAutoFocus(this, R.id.auto_focus);
 }
 break;
 case R.id.restart_preview:
 Log.d(TAG, "Got restart preview message");
 restartPreviewAndDecode();
 break;
 case R.id.decode_succeeded:
　　　　//解码成功，获取到界面的结果和原来的二维码数据
 Log.d(TAG, "Got decode succeeded message");
 state = State.SUCCESS;
 Bundle bundle = message.getData();
 Bitmap barcode = bundle == null ? null :
  (Bitmap) bundle.getParcelable(DecodeThread.BARCODE_BITMAP);
 activity.handleDecode((Result) message.obj, barcode);
 break;
 case R.id.decode_failed:
 // We're decoding as fast as possible, so when one decode fails, start another.
 state = State.PREVIEW;
 CameraManager.get().requestPreviewFrame(decodeThread.getHandler(), R.id.decode);
 break;
 case R.id.return_scan_result:
 Log.d(TAG, "Got return scan result message");
 activity.setResult(Activity.RESULT_OK, (Intent) message.obj);
 activity.finish();
 break;
 case R.id.launch_product_query:
 Log.d(TAG, "Got product query message");
 String url = (String) message.obj;
 Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
 intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
 activity.startActivity(intent);
 break;
 }
}

public void handleDecode(final Result obj, Bitmap barcode)
{
 inactivityTimer.onActivity();
 playBeepSoundAndVibrate();
 AlertDialog.Builder dialog = new AlertDialog.Builder(this);
 if (barcode == null)
 {
 dialog.setIcon(null);
 }
 else
 {

 Drawable drawable = new BitmapDrawable(barcode);
 dialog.setIcon(drawable);
 }
 dialog.setTitle("扫描结果");
 dialog.setMessage(obj.getText());
 dialog.setNegativeButton("确定", new DialogInterface.OnClickListener()
 {
 @Override
 public void onClick(DialogInterface dialog, int which)
 {
  //用默认浏览器打开扫描得到的地址
  Intent intent = new Intent();
  intent.setAction("android.intent.action.VIEW");
  Uri content_url = Uri.parse(obj.getText());
  intent.setData(content_url);
  startActivity(intent);
  finish();
 }
 });
 dialog.setPositiveButton("取消", new DialogInterface.OnClickListener()
 {
 @Override
 public void onClick(DialogInterface dialog, int which)
 {
  finish();
 }
 });
 dialog.create().show();
}

<uses-permission android:name="android.permission.CAMERA"></uses-permission>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />