方向改变时相机出现问题

我正在开发一个应用程序，当设备方向从横向变为纵向或反之亦然时，该应用程序会调用不同的活动。横向模式的活动是增强现实活动，因此我使用相机向用户展示周围环境。但是，当我尝试返回纵向时，应用程序崩溃并显示以下错误：

08-17 16:05:42.622: ERROR/AndroidRuntime(9769): FATAL EXCEPTION: main
08-17 16:05:42.622: ERROR/AndroidRuntime(9769): java.lang.RuntimeException: set display orientation failed
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at android.hardware.Camera.setDisplayOrientation(Native Method)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at es.ucm.look.ar.Preview.surfaceChanged(Preview.java:102)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at android.view.SurfaceView.updateWindow(SurfaceView.java:549)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at android.view.SurfaceView.setFrame(SurfaceView.java:294)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at android.view.View.layout(View.java:7169)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at android.widget.FrameLayout.onLayout(FrameLayout.java:338)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at android.view.View.layout(View.java:7175)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at android.widget.FrameLayout.onLayout(FrameLayout.java:338)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at android.view.View.layout(View.java:7175)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at android.widget.FrameLayout.onLayout(FrameLayout.java:338)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at android.view.View.layout(View.java:7175)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at android.view.ViewRoot.performTraversals(ViewRoot.java:1140)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1859)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at android.os.Handler.dispatchMessage(Handler.java:99)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at android.os.Looper.loop(Looper.java:130)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at android.app.ActivityThread.main(ActivityThread.java:3683)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at java.lang.reflect.Method.invokeNative(Native Method)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at java.lang.reflect.Method.invoke(Method.java:507)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
08-17 16:05:42.622: ERROR/AndroidRuntime(9769):     at dalvik.system.NativeStart.main(Native Method)

从纵向到横向的转换正常进行。

这是我的 Android 清单（活动“EmergciesList”是纵向模式的活动，“MapaMovilAR”是横向模式的活动）：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.list" android:versionCode="1" android:versionName="1.0">
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.INTERNET" />
<application android:icon="@drawable/icon" android:label="@string/app_name"
    android:name="cl.puc.memoria.MapaMovilApplication">
    <activity android:name="cl.puc.memoria.EmergenciesList"
        android:configChanges="orientation" android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN"></action>
            <category android:name="android.intent.category.LAUNCHER">    </category>
        </intent-filter>
    </activity>
    <activity android:name="cl.puc.memoria.AR.MapaMovilAR"
        android:configChanges="orientation">
    </activity>
    <activity android:name="es.ucm.look.ar.LookAR"></activity>

</application>
<uses-sdk android:minSdkVersion="7" />

</manifest> 

最后这是处理方向变化的代码：

@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);

    if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {
        Intent el = new Intent(MapaMovilAR.this,
                cl.puc.memoria.EmergenciesList.class);
        startActivity(el);
    } else if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT) {
        Toast.makeText(this, "portrait", Toast.LENGTH_SHORT).show();
    }
}

有什么可能导致崩溃吗？

Use :

mCamera.stopPreview();
mCamera.setDisplayOrientation(mRotation);
mCamera.startPreview();