安卓二维码识别 Android开发技巧——五分钟实现二维码识别 - Linux - 服务器之家

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安卓二维码识别 Android开发技巧——五分钟实现二维码识别

发布时间:2017-04-14 来源:服务器之家

首先新建一个工程


打开选择之前所下载好的lib project进行依赖:



依赖好之后便是编写我们的界面:acitivity_main.xml:

android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="@+id/btn_scan"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="scan"
/>
<TextView
android:id="@+id/tv_result"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="result"
/>
</LinearLayout>

那界面写好之后,我们需要调用哪些方法才能实现二维码的识别功能呢? 之前我们所依赖的工程中有一个CaptureActivity.java文件,而这个activity便是二维码识别功能的执行以及回调:

/**
* 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@ (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;
}
}

如果你需要学习二维码识别更底层的代码,这里面可是有不少的干货哦,那对我们使用者来说,我们只需要了解这个class的回调方法就行,返回给我们什么参数?key是多少?

/**
* 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();
}

在这其中我们可以看见,它为我们回调了三个参数,分别是宽,高以及字符串(识别出来的内容),而我们,只需要result这个参数,那么知道这些,接下来便是主要代码的编写:EntrenceActivity.java

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);
}
}
}