我在 android 中开发了一个相机应用程序。它使用表面 View 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。

除 Nexus 7 平板电脑外，它在其他手机上运行良好。在 Nexus 7 中，除了最后一个，即 c = Camera.open();，代码在所有情况下都会抛出异常，但对象 c 仍然是 null.

这是堆栈跟踪

11-22 12:36:57.559 W/System.err(7621): java.lang.NullPointerException
11-22 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.access$600(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 Parameter
11-22 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$1.run(OpenCamera.java:336)
11-22 12:36:57.679 W/System.err(7621): java.lang.NullPointerException
11-22 12:36:57.679 W/System.err(7621): at com.MyPackage.OpenCamera.

$MyTimmer$1.run(OpenCamera.java:344)

所以我不能用它来捕捉图像。 有什么解决办法吗？？？

谢谢...

最佳答案

在 Nexus 7 上使用以下代码时: int cameraId = CameraInfo.CAMERA_FACING_FRONT; cameraId 为 1，但是，如您所见，使用 1 作为参数会导致错误。 我发现使用 0 而不是 1 是可行的，但每次使用后都必须释放相机，所以我继续调用 Camera.open(cameraId).release(); 我意识到这很丑陋，但它似乎可以解决 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();
     } 

关于android - 在 Nexus 7 平板电脑中打开相机，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/13509935/