从一次实例的注入看ClassLoader的一个坑

java.lang.NullPointerException
at android.media.MediaPlayer$EventHandler.handleMessage(MediaPlayer.java:2398)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5331)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:832)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:648)
at dalvik.system.NativeStart.main(Native Method) 

package android.media;

import android.os.Looper;
import android.os.Message;

public class SafeEventHandler extends android.media.MediaPlayer.EventHandler {
	public SafeEventHandler(MediaPlayer mp, Looper looper) {
		mp.super(mp, looper);
	}

	public void handleMessage(Message msg) {
		try {
			super.handleMessage(msg);
		} catch (Exception e) {
			e.printStackTrace();
		}

	}
}

		} else if (!dvmCheckClassAccess(clazz, clazz->super)) {
            ALOGW("Superclass of '%s' (%s) is not accessible",
                clazz->descriptor, clazz->super->descriptor);
            dvmThrowIllegalAccessError("superclass not accessible");
            goto bail;
        }

bool dvmCheckClassAccess(const ClassObject* accessFrom,
    const ClassObject* clazz)
{
    if (dvmIsPublicClass(clazz))
        return true;
    return dvmInSamePackage(accessFrom, clazz);
}

/* quick test for intra-class access */
if (class1 == class2)
    return true;

/* class loaders must match */
if (class1->classLoader != class2->classLoader)
    return false;