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.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 = 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();
}
