我正在使用zbar for Android开发条形码扫描仪。 一切都很好。但是，当我的应用程序进入睡眠状态或手机锁定时，相机预览会冻结，我无法在恢复时重新启动它。
fragment.java
package com.alsafeer.xpressions.fragment;
import android.graphics.Typeface;
import android.hardware.Camera;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;
import com.alsafeer.xpressions.AnalyticsSampleApp;
import com.alsafeer.xpressions.CameraPreview;
import com.alsafeer.xpressions.JsonParser;
import com.alsafeer.xpressions.R;
import com.google.android.gms.analytics.GoogleAnalytics;
import com.google.android.gms.analytics.HitBuilders;
import com.google.android.gms.analytics.Tracker;
import net.sourceforge.zbar.Config;
import net.sourceforge.zbar.Image;
import net.sourceforge.zbar.ImageScanner;
import net.sourceforge.zbar.Symbol;
import net.sourceforge.zbar.SymbolSet;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
public class rewards extends Fragment {
private Camera mCamera;
private CameraPreview mPreview;
private Handler autoFocusHandler;
private String Name;
private String Email;
private View view;
private String Mob;
private String Points;
private String result;
private RelativeLayout preview;
TextView scanText;
Button scanButton;
ImageScanner scanner;
private boolean barcodeScanned = false;
private boolean previewing = true;
static {
System.loadLibrary("iconv");
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
setHasOptionsMenu(true);
view = inflater.inflate(R.layout.activity_rewards,
container, false);
view.setFocusableInTouchMode(true);
view.requestFocus();
Tracker t = ((AnalyticsSampleApp) getActivity().getApplication()).getTracker(
AnalyticsSampleApp.TrackerName.APP_TRACKER);
GoogleAnalytics.getInstance(getActivity()).setLocalDispatchPeriod(1);
t.setScreenName("Rewards Barcode Reader");
t.send(new HitBuilders.AppViewBuilder().build());
Typeface font = Typeface.createFromAsset(getActivity().getAssets(), "fonts/font.ttf");
Button next= (Button) view.findViewById(R.id.next);
next.setTypeface(font);
scanText = (EditText)view.findViewById(R.id.editText6);
scanText.setTypeface(font);
mCamera = getCameraInstance();
getActivity().getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_VISIBLE|
WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE);
next.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(!scanText.getText().toString().equals(""))
{
new AsyncTaskParseJson().execute();
}
else
{
Toast.makeText(getActivity(),"Please enter the number or scan the barcode...", Toast.LENGTH_LONG).show();
}
}
});
scanText.setOnKeyListener(new View.OnKeyListener() {
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if (event.getAction() == KeyEvent.ACTION_DOWN) {
if ((keyCode == KeyEvent.KEYCODE_BACK)) {
releaseCamera();
getFragmentManager().beginTransaction().replace(R.id.content_frame, new FirstFragment(), "first").commit();
return true;
}
}
return false;
}
});
view.setOnKeyListener(new View.OnKeyListener() {
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if (event.getAction() == KeyEvent.ACTION_DOWN) {
if ((keyCode == KeyEvent.KEYCODE_BACK)) {
releaseCamera();
getFragmentManager().beginTransaction().replace(R.id.content_frame, new FirstFragment(), "first").commit();
return true;
}
}
return true;
}
});
autoFocusHandler = new Handler();
/* Instance barcode scanner */
scanner = new ImageScanner();
scanner.setConfig(0, Config.X_DENSITY, 3);
scanner.setConfig(0, Config.Y_DENSITY, 3);
mPreview = new CameraPreview(getActivity(), mCamera, previewCb, autoFocusCB);
preview = (RelativeLayout) view.findViewById(R.id.cameraPreview);
preview.addView(mPreview);
scanButton = (Button)view.findViewById(R.id.button6);
scanButton.setTypeface(font);
scanButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
if (barcodeScanned) {
barcodeScanned = false;
mCamera.setPreviewCallback(previewCb);
mCamera.startPreview();
previewing = true;
mCamera.autoFocus(autoFocusCB);
}
}
});
return view;
}
@Override
public void onResume() {
super.onResume();
if(mCamera==null) {
mCamera=getCameraInstance();
mPreview = new CameraPreview(getActivity(), mCamera, previewCb, autoFocusCB);
preview = (RelativeLayout) view.findViewById(R.id.cameraPreview);
preview.addView(mPreview);
mCamera.setPreviewCallback(previewCb);
mCamera.startPreview();
previewing = true;
mCamera.autoFocus(autoFocusCB);
}
}
@Override
public void onPause() {
super.onPause();
}
@Override
public void onStop() {
super.onStop();
releaseCamera();
}
/** A safe way to get an instance of the Camera object. */
public static Camera getCameraInstance(){
Camera c = null;
try {
c = Camera.open();
} catch (Exception e){
}
return c;
}
public void releaseCamera() {
if (mCamera != null) {
previewing = false;
mCamera.setPreviewCallback(null);
mCamera.release();
mCamera = null;
}
}
private Runnable doAutoFocus = new Runnable() {
public void run() {
if (previewing)
mCamera.autoFocus(autoFocusCB);
}
};
Camera.PreviewCallback previewCb = new Camera.PreviewCallback() {
public void onPreviewFrame(byte[] data, Camera camera) {
Camera.Parameters parameters = camera.getParameters();
Camera.Size size = parameters.getPreviewSize();
Image barcode = new Image(size.width, size.height, "Y800");
barcode.setData(data);
int result = scanner.scanImage(barcode);
if (result != 0) {
previewing = false;
mCamera.setPreviewCallback(null);
mCamera.stopPreview();
SymbolSet syms = scanner.getResults();
for (Symbol sym : syms) {
scanText.setText(sym.getData());
barcodeScanned = true;
}
}
}
};
// Mimic continuous auto-focusing
Camera.AutoFocusCallback autoFocusCB = new Camera.AutoFocusCallback() {
public void onAutoFocus(boolean success, Camera camera) {
autoFocusHandler.postDelayed(doAutoFocus, 1000);
}
};
public class AsyncTaskParseJson extends AsyncTask<String, String, String> {
JSONArray dataJsonArr = null;
@Override
protected void onPreExecute() {}
@Override
protected String doInBackground(String... arg0) {
try {
// instantiate our json parser
JsonParser jParser = new JsonParser();
// get json string from url
JSONObject json = jParser.getJSONFromUrl("http://www.safeerplus.ae/ncno="+scanText.getText().toString());
// get the array of users
dataJsonArr = json.getJSONArray("msg");
// loop through all users
JSONObject c = dataJsonArr.getJSONObject(0);
// Storing each json item in variable
Name = c.getString("name");
Mob = c.getString("mob");
Email = c.getString("email");
Points = c.getString("points");
if(Name.equals("")||Mob.equals("")||Email.equals("")||Points.equals(""))
{
}
else {
Bundle args = new Bundle();
args.putString("code", scanText.getText().toString());
args.putString("name1", Name);
args.putString("mob1", Mob);
args.putString("email1", Email);
args.putString("points1", Points);
releaseCamera();
Fragment fr=new reward_details();
FragmentManager fm = getFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
fr.setArguments(args);
ft.replace(R.id.content_frame, fr);
ft.commit();
}
} catch (JSONException e) {
getActivity().runOnUiThread(new Runnable() {
public void run() {
Toast.makeText(getActivity(), "Please use a valid card!", Toast.LENGTH_LONG).show();
}
});
}
return null;
}
@Override
protected void onPostExecute(String strFromDoInBg) {}
}
}
camerapreview.java
package com.alsafeer.xpressions;
import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.AutoFocusCallback;
import android.hardware.Camera.PreviewCallback;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private SurfaceHolder mHolder;
private Camera mCamera;
private PreviewCallback previewCallback;
private AutoFocusCallback autoFocusCallback;
public CameraPreview(Context context, Camera camera,
PreviewCallback previewCb,
AutoFocusCallback autoFocusCb) {
super(context);
mCamera = camera;
previewCallback = previewCb;
autoFocusCallback = autoFocusCb;
/*
* Set camera to continuous focus if supported, otherwise use
* software auto-focus. Only works for API level >=9.
*/
/*
Camera.Parameters parameters = camera.getParameters();
for (String f : parameters.getSupportedFocusModes()) {
if (f == Parameters.FOCUS_MODE_CONTINUOUS_PICTURE) {
mCamera.setFocusMode(Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
autoFocusCallback = null;
break;
}
}
*/
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = getHolder();
mHolder.addCallback(this);
// deprecated setting, but required on Android versions prior to 3.0
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, now tell the camera where to draw the preview.
try {
// open the camera
mCamera = Camera.open();
} catch (RuntimeException e) {
// check for exceptions
System.err.println(e);
return;
}
Camera.Parameters param;
param = mCamera.getParameters();
// modify parameter
param.setPreviewSize(200, 300);
mCamera.setParameters(param);
try {
// The Surface has been created, now tell the camera where to draw
// the preview.
mCamera.setPreviewDisplay(holder);
mCamera.startPreview();
} catch (Exception e) {
// check for exceptions
System.err.println(e);
return;
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
setMeasuredDimension(getMeasuredWidth(), getMeasuredWidth()); //Snap to width
}
public void surfaceDestroyed(SurfaceHolder holder) {
}
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
Camera.Parameters parameters = mCamera.getParameters();
final DisplayMetrics dm = this.getResources().getDisplayMetrics();
//getBestPreviewSize returns the best preview size, don't worry
//but some devices do not return one for all camera matching the aspect ratio
/*
* If your preview can change or rotate, take care of those events here.
* Make sure to stop the preview before resizing or reformatting it.
*/
if (mHolder.getSurface() == null){
// preview surface does not exist
return;
}
// stop preview before making changes
try {
mCamera.stopPreview();
} catch (Exception e){
// ignore: tried to stop a non-existent preview
}
try {
// Hard code camera surface rotation 90 degs to match Activity view in portrait
mCamera.setDisplayOrientation(90);
mCamera.setPreviewDisplay(mHolder);
mCamera.setPreviewCallback(previewCallback);
mCamera.startPreview();
mCamera.autoFocus(autoFocusCallback);
} catch (Exception e){
Log.d("DBG", "Error starting camera preview: " + e.getMessage());
}
}
}
Layout.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="16dp"
android:background="#e7e7e9">
<RelativeLayout
android:id="@+id/cameraPreview"
android:layout_width="300dp"
android:layout_height="300dp"
android:layout_weight="1"
android:gravity="clip_horizontal"
android:layout_below="@+id/editText6"
android:layout_centerHorizontal="true">
</RelativeLayout>
<Button
android:id="@+id/next"
android:text="View points"
android:layout_width="120dp"
android:layout_height="30sp"
android:layout_gravity="center"
android:background="@drawable/loginbutton"
android:textSize="12sp"
android:layout_alignTop="@+id/button6"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
<Button
android:id="@+id/button6"
android:text="Rescan"
android:layout_width="120dp"
android:layout_height="30sp"
android:layout_gravity="center"
android:background="@drawable/loginbutton"
android:textSize="12sp"
android:layout_below="@+id/cameraPreview"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="30dp" />
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="number"
android:ems="10"
android:id="@+id/editText6"
android:background="#d1d2d4"
android:textSize="15sp"
android:padding="5dp"
android:textColor="#000000"
android:hint="Enter or Scan the Barcode"
android:textColorHint="#4a4f5a"
android:layout_alignParentTop="true"
android:layout_alignLeft="@+id/cameraPreview"
android:layout_alignStart="@+id/cameraPreview"
android:layout_alignRight="@+id/cameraPreview"
android:layout_alignEnd="@+id/cameraPreview" />
</RelativeLayout>
logcat的
04-20 10:40:20.356 7099-7099/com.alsafeer.xpressions D/Camera-JNI﹕ setHasPreviewCallback: installed:1, manualBuffer:0 04-20 10:40:20.359 7099-7099/com.alsafeer.xpressions I/CameraFramework﹕ Camera framework getParameters =afeng-max-focus-step=0;afeng-min-focus-step=0;antibanding=auto;antibanding-values=off,50hz,60hz,auto;auto-exposure-lock-supported=true;auto-whitebalance-lock-supported=true;brightness=middle;brightness-values=low,middle,high;brightness_value=39;burst-num=1;cap-mode=normal;cap-mode-values=normal,face_beauty,continuousshot,smileshot,bestshot,evbracketshot,autorama,mav,asd;capfname=/sdcard/DCIM/cap00;contrast=middle;contrast-values=low,middle,high;edge=middle;edge-values=low,middle,high;effect=none;effect-values=none,mono,negative,sepia,aqua,whiteboard,blackboard;eng-flash-duty-max=1;eng-flash-duty-min=0;eng-flash-duty-value=-1;exposure-compensation=0;exposure-compensation-step=1.0;fb-sharp=0;fb-sharp-max=4;fb-sharp-min=-4;fb-skin-color=0;fb-skin-color-max=4;fb-skin-color-min=-4;fb-smooth-level=0;fb-smooth-level-max=4;fb-smooth-level-min=-4;focal-length=3.5;focus-distances=0.95,1.9,Infinity;focus-mode=infinity;focus-mode-values=infinity;horizontal-view-angle=54;hue=middle;hue-values=low,middle,high;iso-speed=auto;iso-speed-values=auto,100,200,400,800,1600;jpeg-quality=100;jpeg-thumbnail-height=128;jpeg-thumbnail-quality=100;jpeg-thumbnail-size-values=0x0,160x128,320x240;jpeg-thumbnail-width=160;max-exposure-compensation=3;max-num-detected-faces-hw=15;max-num-detected-faces-sw=0;max-num-focus-areas=0;max-num-metering-areas=9;max-zoom=10;min-exposure-compensation=-3;mtk-cam-mode=0;picture-format=jpeg;picture-format-values=jpeg;picture-size=2560x1920;picture-size-values=320x240,640x480,1024x768,1280x720,1280x768,1280x960,1600x1200,2048x1536,2560x1440,2560x1920,2880x1728;preferred-preview-size-for-video=1280x720;preview-format=yuv420sp;preview-format-values=yuv420sp,yuv420p,yuv420i-yyuvyy-3plane;preview-fps-range=5000,60000;preview-fps-range-values=(5000,60000);preview-frame-rate=30;preview-frame-rate-values=15,24,30;preview-size=640x480;preview-size-values=176x144,320x240,352x288,480x320,480x368,640x480,720x480,800x480,800x600,864x480,960x540,1280x720;rotation=0;saturation=middle;saturation-values=low,middle,high;scene-mode=auto;scene-mode-values=auto,portrait,landscape,night,night-portrait,theatre,beach,snow,sunset,steadyphoto,fireworks,sports,party,candlelight,hdr;sensor-type=254;smooth-zoom-supported=true;vertical-view-angle=49;video-frame-format=yuv420p;video-size=640x480;video-size-values=176x144,480x320,640x480,864x480,1280x720,1920x1080;video-snapshot-supported=false;video-stabilization=false;video-stabilization-supported=true;whitebalance=auto;whitebalance-values=auto,incandescent,fluorescent,warm-fluorescent,daylight,cloudy-daylight,twilight,shade;zoom=0;zoom-ratios=100,114,132,151,174,200,229,263,303,348,400;zoom-supported=true;zsd-mode=off;zsd-mode-values=off,on 04-20 10:40:20.390 7099-7112/com.alsafeer.xpressions D/Camera-JNI﹕ Allocating callback buffer 04-20 10:40:20.418 7099-7099/com.alsafeer.xpressions I/CameraFramework﹕ handleMessage: 16 04-20 10:40:20.418 7099-7099/com.alsafeer.xpressions D/Camera-JNI﹕ setHasPreviewCallback: installed:1, manualBuffer:0 04-20 10:40:20.420 7099-7099/com.alsafeer.xpressions I/CameraFramework﹕ Camera framework getParameters =afeng-max-focus-step=0;afeng-min-focus-step=0;antibanding=auto;antibanding-values=off,50hz,60hz,auto;auto-exposure-lock-supported=true;auto-whitebalance-lock-supported=true;brightness=middle;brightness-values=low,middle,high;brightness_value=39;burst-num=1;cap-mode=normal;cap-mode-values=normal,face_beauty,continuousshot,smileshot,bestshot,evbracketshot,autorama,mav,asd;capfname=/sdcard/DCIM/cap00;contrast=middle;contrast-values=low,middle,high;edge=middle;edge-values=low,middle,high;effect=none;effect-values=none,mono,negative,sepia,aqua,whiteboard,blackboard;eng-flash-duty-max=1;eng-flash-duty-min=0;eng-flash-duty-value=-1;exposure-compensation=0;exposure-compensation-step=1.0;fb-sharp=0;fb-sharp-max=4;fb-sharp-min=-4;fb-skin-color=0;fb-skin-color-max=4;fb-skin-color-min=-4;fb-smooth-level=0;fb-smooth-level-max=4;fb-smooth-level-min=-4;focal-length=3.5;focus-distances=0.95,1.9,Infinity;focus-mode=infinity;focus-mode-values=infinity;horizontal-view-angle=54;hue=middle;hue-values=low,middle,high;iso-speed=auto;iso-speed-values=auto,100,200,400,800,1600;jpeg-quality=100;jpeg-thumbnail-height=128;jpeg-thumbnail-quality=100;jpeg-thumbnail-size-values=0x0,160x128,320x240;jpeg-thumbnail-width=160;max-exposure-compensation=3;max-num-detected-faces-hw=15;max-num-detected-faces-sw=0;max-num-focus-areas=0;max-num-metering-areas=9;max-zoom=10;min-exposure-compensation=-3;mtk-cam-mode=0;picture-format=jpeg;picture-format-values=jpeg;picture-size=2560x1920;picture-size-values=320x240,640x480,1024x768,1280x720,1280x768,1280x960,1600x1200,2048x1536,2560x1440,2560x1920,2880x1728;preferred-preview-size-for-video=1280x720;preview-format=yuv420sp;preview-format-values=yuv420sp,yuv420p,yuv420i-yyuvyy-3plane;preview-fps-range=5000,60000;preview-fps-range-values=(5000,60000);preview-frame-rate=30;preview-frame-rate-values=15,24,30;preview-size=640x480;preview-size-values=176x144,320x240,352x288,480x320,480x368,640x480,720x480,800x480,800x600,864x480,960x540,1280x720;rotation=0;saturation=middle;saturation-values=low,middle,high;scene-mode=auto;scene-mode-values=auto,portrait,landscape,night,night-portrait,theatre,beach,snow,sunset,steadyphoto,fireworks,sports,party,candlelight,hdr;sensor-type=254;smooth-zoom-supported=true;vertical-view-angle=49;video-frame-format=yuv420p;video-size=640x480;video-size-values=176x144,480x320,640x480,864x480,1280x720,1920x1080;video-snapshot-supported=false;video-stabilization=false;video-stabilization-supported=true;whitebalance=auto;whitebalance-values=auto,incandescent,fluorescent,warm-fluorescent,daylight,cloudy-daylight,twilight,shade;zoom=0;zoom-ratios=100,114,132,151,174,200,229,263,303,348,400;zoom-supported=true;zsd-mode=off;zsd-mode-values=off,on 04-20 10:40:20.457 7099-7099/com.alsafeer.xpressions D/Camera-JNI﹕ setHasPreviewCallback: installed:0, manualBuffer:0 04-20 10:40:20.458 7099-7112/com.alsafeer.xpressions W/Camera-JNI﹕ callback on dead camera object 04-20 10:40:20.458 7099-7099/com.alsafeer.xpressions D/Camera-JNI﹕ (tid:7099)[native_release] + context=0x66e3fc70 camera=0x63f70e30 04-20 10:40:20.458 7099-7099/com.alsafeer.xpressions D/Camera-JNI﹕ [native_release] context->getStrongCount(2) camera->getStrongCount(2) 04-20 10:40:21.023 7099-7099/com.alsafeer.xpressions D/Camera-JNI﹕ (tid:7099)[native_release] - context=0x66e3fc70 camera=0x0 04-20 10:40:21.023 7099-7099/com.alsafeer.xpressions D/Camera-JNI﹕ (tid:7099)[release camera] - X context=0x66e3fc70 04-20 10:40:21.024 7099-7111/com.alsafeer.xpressions D/IPCThreadState﹕ [DN #5] BR_CLEAR_DEATH_NOTIFICATION_DONE cookie 0x66e3fba8 04-20 10:40:21.027 7099-7151/com.alsafeer.xpressions D/Camera-JNI﹕ (tid:7151)[~MtkJNICameraContext] this:0x66e3fc70 04-20 10:40:21.066 7099-7099/com.alsafeer.xpressions I/Choreographer﹕ Skipped 41 frames! The application may be doing too much work on its main thread. 04-20 10:40:21.089 7099-7099/com.alsafeer.xpressions D/GraphicBuffer﹕ create handle(0x623e35c0) (w:480, h:790, f:1) 04-20 10:40:21.121 7099-7099/com.alsafeer.xpressions I/SurfaceTextureClient﹕ [STC::queueBuffer] (this:0x63159d68) fps:0.09, dur:10931.96, max:10931.96, min:10931.96 04-20 10:40:21.121 7099-7099/com.alsafeer.xpressions I/SurfaceTextureClient﹕ [STC::queueBuffer] this:0x63159d68, api:1, last queue time elapsed:10931.96 04-20 10:40:21.130 7099-7099/com.alsafeer.xpressions D/OpenGLRenderer﹕ Flushing caches (mode 0)
答案 0 :(得分：1)
似乎每次应用程序恢复时（onResume），您都在重新创建CameraPreview视图并将其添加到您的布局中。当您在应用程序中，切换到另一个然后再回来时，是否也会发生此问题？如果在这种情况下它也会冻结，我会怀疑你需要在添加新的CameraPreview视图实例之前从布局中删除它。