android – 在Nexus 7平板电脑中打开相机

概述我在 android中开发了一个Camera应用程序.它使用表面视图捕获图像.下面是我用来打开相机的代码 try { // attempt to get a Front Camera instance c = Camera.open(Camera.CameraInfo.CAMERA_FACING_FRONT); } catch (Ex 我在 android中开发了一个Camera应用程序.它使用表面视图捕获图像.下面是我用来打开相机的代码

try {            // attempt to get a Front Camera instance            c = Camera.open(Camera.CameraInfo.CAMERA_FACING_FRONT);        } catch (Exception e) {            // Todo auto-generated catch block            System.out                    .println("fail to connect to Front Camera");        }        if (c == null) {            try {                // attempt to get a Back Camera instance                c = Camera.open(1);            } catch (Exception e) {                // Todo: handle exception                System.out                        .println("fail to connect to Camera   with      ID   =   1");            }        }        if (c == null) {            try {                // attempt to get a Back Camera instance                c = Camera.open(0);            } catch (Exception e) {                // Todo: handle exception                System.out                        .println("fail to connect to Camera   with      ID   =   0");            }        }        if (c == null) {            try {                // attempt to get a Back Camera instance                c = Camera.open();            } catch (Exception e) {                // Todo: handle exception                System.out                        .println("fail to connect to Back Camera");                return c;            }

其中c是Camera的对象.

它在除Nexus 7平板电脑之外的其他手机中运行良好.在Nexus 7中,代码在所有情况下抛出异常,除了最后一个,即c = Camera.open();,但对象c仍为null.

这是堆栈跟踪

11-22 12:36:57.559 W/System.err(7621): java.lang.NullPointerException11-22 12:36:57.559 W/System.err(7621): at com.MyPackage.OpenCamera.getFrontCameraInstance(OpenCamera.java:238)11-22 12:36:57.559 W/System.err(7621): at com.MyPackage.OpenCamera.onCreate(OpenCamera.java:123)11-22 12:36:57.559 W/System.err(7621): at androID.app.Activity.performCreate(Activity.java:5104)11-22 12:36:57.559 W/System.err(7621): at androID.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)11-22 12:36:57.559 W/System.err(7621): at androID.app.ActivityThread.performlaunchActivity(ActivityThread.java:2144)11-22 12:36:57.559 W/System.err(7621): at androID.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)11-22 12:36:57.559 W/System.err(7621): at androID.app.ActivityThread.access0(ActivityThread.java:141)11-22 12:36:57.559 W/System.err(7621): at androID.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)11-22 12:36:57.559 W/System.err(7621): at androID.os.Handler.dispatchMessage(Handler.java:99)11-22 12:36:57.559 W/System.err(7621): at androID.os.Looper.loop(Looper.java:137)11-22 12:36:57.559 W/System.err(7621): at androID.app.ActivityThread.main(ActivityThread.java:5039)11-22 12:36:57.559 W/System.err(7621): at java.lang.reflect.Method.invokeNative(Native Method)11-22 12:36:57.559 W/System.err(7621): at java.lang.reflect.Method.invoke(Method.java:511)11-22 12:36:57.559 W/System.err(7621): at com.androID.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)11-22 12:36:57.559 W/System.err(7621): at com.androID.internal.os.ZygoteInit.main(ZygoteInit.java:560)11-22 12:36:57.559 W/System.err(7621): at dalvik.system.NativeStart.main(Native Method)11-22 12:36:57.559 I/System.out(7621): Error in setting Parameter11-22 12:36:57.609 I/ActivityManager(480): displayed 11-22 12:36:57.679 W/System.err(7621): at androID.location.Geocoder.getFromLocation(Geocoder.java:136)11-22 12:36:57.679 W/System.err(7621): at com.MyPackage.OpenCamera.$MyTimmer.run(OpenCamera.java:336)11-22 12:36:57.679 W/System.err(7621): java.lang.NullPointerException11-22 12:36:57.679 W/System.err(7621): at com.MyPackage.OpenCamera.$MyTimmer.run(OpenCamera.java:344)

所以我不能用它来捕捉图像.
有什么办法吗

谢谢…

解决方法 在Nexus 7上使用以下代码时：
int cameraID = CameraInfo.CAMERA_FACING_FRONT;
但是,如您所见,cameraID为1,使用1作为参数会导致错误.
我发现使用0代替1可以工作,但每次使用后必须释放相机,所以我继续调用Camera.open(cameraID).release();
我意识到这很难看,但它似乎解决了Nexus 7的问题.

int cameraID = -1;    boolean errorFound = false;    boolean hasFeatCamera = getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA);    if (hasFeatCamera) {            try{                 cameraID = CameraInfo.CAMERA_FACING_BACK;                 Camera.open(cameraID).release();                }catch(Exception e){                    Camera.open(0).release();                }    } else if(CameraInfo.CAMERA_FACING_FRONT>-1){        try{         cameraID = CameraInfo.CAMERA_FACING_FRONT;         Camera.open(cameraID).release();        }catch(Exception e){            errorFound = true;        }        if(errorFound){            try{                Camera.open(0).release(); // Put in for Nexus 7 as  CameraInfo.CAMERA_FACING_FRONT= 1 but it only loads if the ID is actually 0                cameraID = 0;            }catch(Exception e){                cameraID = -1;            }        }    }    if(cameraID<0){        Toast.makeText(this,"No camera found.",Toast.LENGTH_LONG).show();     }

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