Android开发技巧之五分钟实现二维码识别

xml version="1.0" encoding="utf-8"?>
xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_match_parent"
    android:layout_match_parent">



            android:id="@+id/btn_scan"
        android:layout_match_parent"
        android:layout_wrap_content"
        android:text="scan"
        />

            android:id="@+id/tv_result"
        android:layout_wrap_content"
        android:layout_wrap_content"
        android:text="result"
        />

/**
 * This activity opens the camera and does the actual scanning on a background
 * thread. It draws a viewfinder to help the user place the barcode correctly,
 * shows feedback as the image processing is happening, and then overlays the
 * results when a scan is successful.
 *
 * @author dswitkin@google.com (Daniel Switkin)
 * @author Sean Owen
 */
public final class CaptureActivity extends Activity implements SurfaceHolder.Callback {

    private static final String TAG = CaptureActivity.class.getSimpleName();

    private CameraManager cameraManager;
    private CaptureActivityHandler handler;
    private InactivityTimer inactivityTimer;
    private BeepManager beepManager;

    private SurfaceView scanPreview = null;
    private RelativeLayout scanContainer;
    private RelativeLayout scanCropView;
    private ImageView scanLine;

    private Rect mCropRect = null;
    private boolean isHasSurface = false;

    public Handler getHandler() {
        return handler;
    }

    public CameraManager getCameraManager() {
        return cameraManager;
    }

    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);

        Window window = getWindow();
        window.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
        setContentView(R.layout.activity_capture);

        scanPreview = (SurfaceView) findViewById(R.id.capture_preview);
        scanContainer = (RelativeLayout) findViewById(R.id.capture_container);
        scanCropView = (RelativeLayout) findViewById(R.id.capture_crop_view);
        scanLine = (ImageView) findViewById(R.id.capture_scan_line);

        inactivityTimer = new InactivityTimer(this);
        beepManager = new BeepManager(this);

        TranslateAnimation animation = new TranslateAnimation(Animation.RELATIVE_TO_PARENT, 0.0f, Animation
                .RELATIVE_TO_PARENT, 0.0f, Animation.RELATIVE_TO_PARENT, 0.0f, Animation.RELATIVE_TO_PARENT,
                0.9f);
        animation.setDuration(4500);
        animation.setRepeatCount(-1);
        animation.setRepeatMode(Animation.RESTART);
        scanLine.startAnimation(animation);
    }

    @Override
    protected void onResume() {
        super.onResume();

        // CameraManager must be initialized here, not in onCreate(). This is
        // necessary because we don't
        // want to open the camera driver and measure the screen size if we're
        // going to show the help on
        // first launch. That led to bugs where the scanning rectangle was the
        // wrong size and partially
        // off screen.
        cameraManager = new CameraManager(getApplication());

        handler = null;

        if (isHasSurface) {
            // The activity was paused but not stopped, so the surface still
            // exists. Therefore
            // surfaceCreated() won't be called, so init the camera here.
            initCamera(scanPreview.getHolder());
        } else {
            // Install the callback and wait for surfaceCreated() to init the
            // camera.
            scanPreview.getHolder().addCallback(this);
        }

        inactivityTimer.onResume();
    }

    @Override
    protected void onPause() {
        if (handler != null) {
            handler.quitSynchronously();
            handler = null;
        }
        inactivityTimer.onPause();
        beepManager.close();
        cameraManager.closeDriver();
        if (!isHasSurface) {
            scanPreview.getHolder().removeCallback(this);
        }
        super.onPause();
    }

    @Override
    protected void onDestroy() {
        inactivityTimer.shutdown();
        super.onDestroy();
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        if (holder == null) {
            Log.e(TAG, "*** WARNING *** surfaceCreated() gave us a null surface!");
        }
        if (!isHasSurface) {
            isHasSurface = true;
            initCamera(holder);
        }
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        isHasSurface = false;
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

    }

    /**
 * A valid barcode has been found, so give an indication of success and show
 * the results.
 *
 * @param rawResult The contents of the barcode.
 * @param bundle The extras
 */
 public void handleDecode(Result rawResult, Bundle bundle) {
        inactivityTimer.onActivity();
        beepManager.playBeepSoundAndVibrate();

        Intent resultIntent = new Intent();
        bundle.putInt("width", mCropRect.width());
        bundle.putInt("height", mCropRect.height());
        bundle.putString("result", rawResult.getText());
        resultIntent.putExtras(bundle);
        this.setResult(RESULT_OK, resultIntent);
        CaptureActivity.this.finish();
    }

    private void initCamera(SurfaceHolder surfaceHolder) {
        if (surfaceHolder == null) {
            throw new IllegalStateException("No SurfaceHolder provided");
        }
        if (cameraManager.isOpen()) {
            Log.w(TAG, "initCamera() while already open -- late SurfaceView callback?");
            return;
        }
        try {
            cameraManager.openDriver(surfaceHolder);
            // Creating the handler starts the preview, which can also throw a
            // RuntimeException.
            if (handler == null) {
                handler = new CaptureActivityHandler(this, cameraManager, DecodeThread.ALL_MODE);
            }

            initCrop();
        } catch (IOException ioe) {
            Log.w(TAG, ioe);
            displayFrameworkBugMessageAndExit();
        } catch (RuntimeException e) {
            // Barcode Scanner has seen crashes in the wild of this variety:
            // java.?lang.?RuntimeException: Fail to connect to camera service
            Log.w(TAG, "Unexpected error initializing camera", e);
            displayFrameworkBugMessageAndExit();
        }
    }

    private void displayFrameworkBugMessageAndExit() {
        // camera error
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle(getString(R.string.app_name));
        builder.setMessage("Camera error");
        builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {
                finish();
            }

        });
        builder.setOnCancelListener(new DialogInterface.OnCancelListener() {

            @Override
            public void onCancel(DialogInterface dialog) {
                finish();
            }
        });
        builder.show();
    }

    public void restartPreviewAfterDelay(long delayMS) {
        if (handler != null) {
            handler.sendEmptyMessageDelayed(R.id.restart_preview, delayMS);
        }
    }

    public Rect getCropRect() {
        return mCropRect;
    }

    /**
 * 初始化截取的矩形区域
 */
 private void initCrop() {
        int cameraWidth = cameraManager.getCameraResolution().y;
        int cameraHeight = cameraManager.getCameraResolution().x;

        /** 获取布局中扫描框的位置信息 */
 int[] location = new int[2];
        scanCropView.getLocationInWindow(location);

        int cropLeft = location[0];
        int cropTop = location[1] - getStatusBarHeight();

        int cropWidth = scanCropView.getWidth();
        int cropHeight = scanCropView.getHeight();

        /** 获取布局容器的宽高 */
 int cOntainerWidth= scanContainer.getWidth();
        int cOntainerHeight= scanContainer.getHeight();

        /** 计算最终截取的矩形的左上角顶点x坐标 */
 int x = cropLeft * cameraWidth / containerWidth;
        /** 计算最终截取的矩形的左上角顶点y坐标 */
 int y = cropTop * cameraHeight / containerHeight;

        /** 计算最终截取的矩形的宽度 */
 int width = cropWidth * cameraWidth / containerWidth;
        /** 计算最终截取的矩形的高度 */
 int height = cropHeight * cameraHeight / containerHeight;

        /** 生成最终的截取的矩形 */
 mCropRect = new Rect(x, y, width + x, height + y);
    }

    private int getStatusBarHeight() {
        try {
            Class c = Class.forName("com.android.internal.R$dimen");
            Object obj = c.newInstance();
            Field field = c.getField("status_bar_height");
            int x = Integer.parseInt(field.get(obj).toString());
            return getResources().getDimensionPixelSize(x);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return 0;
    }
}

/**
 * A valid barcode has been found, so give an indication of success and show
 * the results.
 *
 * @param rawResult The contents of the barcode.
 * @param bundle The extras
 */
public void handleDecode(Result rawResult, Bundle bundle) {
    inactivityTimer.onActivity();
    beepManager.playBeepSoundAndVibrate();

    Intent resultIntent = new Intent();
    bundle.putInt("width", mCropRect.width());
    bundle.putInt("height", mCropRect.height());
    bundle.putString("result", rawResult.getText());
    resultIntent.putExtras(bundle);
    this.setResult(RESULT_OK, resultIntent);
    CaptureActivity.this.finish();
}

public class EntrenceActivity extends AppCompatActivity {
    private Button mBtnScanner;
    private TextView mTvResult;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_entrence);

        initview();

    }

    private void initview() {
        mBtnScanner = (Button) findViewById(R.id.btn_scan);
        mTvResult = (TextView) findViewById(R.id.tv_result);

        mBtnScanner.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                startActivityForResult(new Intent(EntrenceActivity.this , CaptureActivity.class) , 0);

            }
        });

    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (resultCode == RESULT_OK){
            Bundle bundle = data.getExtras();
            String result = bundle.getString("result");
            mTvResult.setText(result);
        }

    }
}