这是与NDK和Android SDK相关的问题。 目前，我的C代码正在调用Java中定义的方法。此方法称为callFromNDK（）。
在这种方法中，我引用媒体播放器的一个实例来播放一个简短的测试音。 callFromNDK（）每2秒调用一次。测试音调本身就是一秒钟。
我看到的是一个 （SIGSEGV），代码1（SEGV_MAPERR），故障addr fffffff4有时。
我想知道是否会发生这种情况，因为媒体播放器实例是在与其使用的上下文不同的上下文中创建的？
这是相关的代码片段[Java文件]
public class Canvastutorial extends Activity {
private static MediaPlayer mediaPlayer = null;
public void callFromNDK() {
if (mediaPlayer != null) {
mediaPlayer.start();
}
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mediaPlayer = MediaPlayer.create(getApplicationContext(), R.raw.audioclip);
mediaPlayer.setLooping(false);
}
@Override
protected void onDestroy() {
mediaPlayer.release();
mediaPlayer = null;
System.gc();
super.onDestroy();
}
@Override
protected void onPause() {
stopAndPrepare();
super.onPause();
}
private void stopAndPrepare() {
mediaPlayer.stop();
try {
mediaPlayer.prepare();
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
mediaPlayer.seekTo(0);
}
}
当应用程序崩溃时，LogCat如下所示：
04-27 10:42:13.228: I/DEBUG(8926): Build fingerprint: 'google/passion/passion:2.3.6/GRK39F/189904:user/release-keys'
04-27 10:42:13.228: I/DEBUG(8926): pid: 10362, tid: 11222 >>> <package_name> <<<
04-27 10:42:13.228: I/DEBUG(8926): signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr fffffff4
04-27 10:42:13.238: I/DEBUG(8926): r0 4214cdc0 r1 00000000 r2 00000000 r3 0000ce68
04-27 10:42:13.238: I/DEBUG(8926): r4 44628398 r5 00000000 r6 4472fbd8 r7 0000000e
04-27 10:42:13.238: I/DEBUG(8926): r8 80018000 r9 00000000 10 00000000 fp 800a5368
04-27 10:42:13.238: I/DEBUG(8926): ip 00000000 sp 4472fb88 lr 8001d084 pc 8001d090 cpsr 60000010
04-27 10:42:13.238: I/DEBUG(8926): d0 00650072006800b8 d1 00000044bed7f457
04-27 10:42:13.238: I/DEBUG(8926): d2 0069006400650052 d3 004d0049002e0040
04-27 10:42:13.238: I/DEBUG(8926): d4 0061006900640065 d5 00790061006c0050
04-27 10:42:13.238: I/DEBUG(8926): d6 0065005300720065 d7 0063006900760072
04-27 10:42:13.238: I/DEBUG(8926): d8 0000000000000000 d9 0000000042ba56de
04-27 10:42:13.238: I/DEBUG(8926): d10 0000000000000000 d11 0000000000000000
04-27 10:42:13.238: I/DEBUG(8926): d12 0000000000000000 d13 0000000000000000
04-27 10:42:13.238: I/DEBUG(8926): d14 0000000000000000 d15 0000000000000000
04-27 10:42:13.238: I/DEBUG(8926): d16 0000000000000001 d17 c053000000000000
04-27 10:42:13.238: I/DEBUG(8926): d18 0000000000000000 d19 0000000000000000
04-27 10:42:13.238: I/DEBUG(8926): d20 3ff0000000000000 d21 8000000000000000
04-27 10:42:13.238: I/DEBUG(8926): d22 0000000000000000 d23 ff00000000000000
04-27 10:42:13.238: I/DEBUG(8926): d24 ff00000000000000 d25 ff00000000000000
04-27 10:42:13.238: I/DEBUG(8926): d26 0100010001000100 d27 0100010001000100
04-27 10:42:13.238: I/DEBUG(8926): d28 0100010001000100 d29 3ff0000000000000
04-27 10:42:13.238: I/DEBUG(8926): d30 0000000000000000 d31 3ff0000000000000
04-27 10:42:13.238: I/DEBUG(8926): scr 60000012
04-27 10:42:13.328: I/DEBUG(8926): #00 pc 0001d090 /system/lib/libdvm.so
04-27 10:42:13.328: I/DEBUG(8926): #01 pc 000220e4 /system/lib/libdvm.so
04-27 10:42:13.328: I/DEBUG(8926): #02 pc 00020fdc /system/lib/libdvm.so
04-27 10:42:13.328: I/DEBUG(8926): #03 pc 0005fc40 /system/lib/libdvm.so
04-27 10:42:13.328: I/DEBUG(8926): #04 pc 0004cff8 /system/lib/libdvm.so
04-27 10:42:13.328: I/DEBUG(8926): #05 pc 00001590 /data/data/<package_name>/lib/libtest-jni.so
04-27 10:42:13.328: I/DEBUG(8926): #06 pc 000016ca /data/data/<package_name>/lib/libtest-jni.so
04-27 10:42:13.328: I/DEBUG(8926): #07 pc 000118e4 /system/lib/libc.so
04-27 10:42:13.328: I/DEBUG(8926): #08 pc 000114b0 /system/lib/libc.so
04-27 10:42:13.328: I/DEBUG(8926): code around pc:
04-27 10:42:13.328: I/DEBUG(8926): 8001d070 fa0108cc ea000017 e3a00001 e3a09000
04-27 10:42:13.328: I/DEBUG(8926): 8001d080 ebffff72 e2450014 e5905000 e5909004
04-27 10:42:13.328: I/DEBUG(8926): 8001d090 e515200c e5963018 e3520000 1592a000
04-27 10:42:13.328: I/DEBUG(8926): 8001d0a0 e3a01000 0affff8a e1f970b6 e5862010
04-27 10:42:13.328: I/DEBUG(8926): 8001d0b0 e59a1028 e5835028 e590a010 e1a04009
04-27 10:42:13.328: I/DEBUG(8926): code around lr:
04-27 10:42:13.328: I/DEBUG(8926): 8001d064 e088f30c e1a01000 e5960018 fa0108cc
04-27 10:42:13.328: I/DEBUG(8926): 8001d074 ea000017 e3a00001 e3a09000 ebffff72
04-27 10:42:13.328: I/DEBUG(8926): 8001d084 e2450014 e5905000 e5909004 e515200c
04-27 10:42:13.328: I/DEBUG(8926): 8001d094 e5963018 e3520000 1592a000 e3a01000
04-27 10:42:13.328: I/DEBUG(8926): 8001d0a4 0affff8a e1f970b6 e5862010 e59a1028
04-27 10:42:13.328: I/DEBUG(8926): stack:
04-27 10:42:13.328: I/DEBUG(8926): 4472fb48 4472fbe0
04-27 10:42:13.328: I/DEBUG(8926): 4472fb4c 4214cce4
04-27 10:42:13.328: I/DEBUG(8926): 4472fb50 0000ce60
04-27 10:42:13.328: I/DEBUG(8926): 4472fb54 00000001
04-27 10:42:13.328: I/DEBUG(8926): 4472fb58 4472fbe0
04-27 10:42:13.338: I/DEBUG(8926): 4472fb5c 80049697 /system/lib/libdvm.so
04-27 10:42:13.338: I/DEBUG(8926): 4472fb60 4214cce4
04-27 10:42:13.338: I/DEBUG(8926): 4472fb64 431fbec9
04-27 10:42:13.338: I/DEBUG(8926): 4472fb68 ad34675d /system/lib/libandroid_runtime.so
04-27 10:42:13.338: I/DEBUG(8926): 4472fb6c 4472fbe0
04-27 10:42:13.338: I/DEBUG(8926): 4472fb70 42f8e91e
04-27 10:42:13.338: I/DEBUG(8926): 4472fb74 4214cd00
04-27 10:42:13.338: I/DEBUG(8926): 4472fb78 4472fbd8
04-27 10:42:13.338: I/DEBUG(8926): 4472fb7c 40038360
04-27 10:42:13.338: I/DEBUG(8926): 4472fb80 df002777
04-27 10:42:13.338: I/DEBUG(8926): 4472fb84 e3a070ad
04-27 10:42:13.338: I/DEBUG(8926): #00 4472fb88 4214e32c
04-27 10:42:13.338: I/DEBUG(8926): 4472fb8c 4472fbd8
04-27 10:42:13.338: I/DEBUG(8926): 4472fb90 00000001
04-27 10:42:13.338: I/DEBUG(8926): 4472fb94 002c2c40
04-27 10:42:13.338: I/DEBUG(8926): 4472fb98 0000ce68
04-27 10:42:13.338: I/DEBUG(8926): 4472fb9c 000f45b8
04-27 10:42:13.338: I/DEBUG(8926): 4472fba0 800aad38
04-27 10:42:13.338: I/DEBUG(8926): 4472fba4 fffffe84
04-27 10:42:13.338: I/DEBUG(8926): 4472fba8 800a5368
04-27 10:42:13.338: I/DEBUG(8926): 4472fbac 800220e8 /system/lib/libdvm.so
04-27 10:42:13.338: I/DEBUG(8926): #01 4472fbb0 4472fbd8
04-27 10:42:13.338: I/DEBUG(8926): 4472fbb4 0000ce60
04-27 10:42:13.338: I/DEBUG(8926): 4472fbb8 80022058 /system/lib/libdvm.so
04-27 10:42:13.338: I/DEBUG(8926): 4472fbbc 423298c8
04-27 10:42:13.338: I/DEBUG(8926): 4472fbc0 00000000
04-27 10:42:13.338: I/DEBUG(8926): 4472fbc4 80020fe0 /system/lib/libdvm.so
任何想法都表示赞赏。
感谢。
项目的本机端：定期调用thread_function get（间隔2秒），这就是我调用Java代码中定义的函数的地方。
// Callbacks to Android
JavaVM *j_vm;
jobject *j_obj;
JNIEnv *j_env;
jclass j_cls;
jmethodID android_call;
int JNI_OnLoad(JavaVM* vm, void* reserved) {
j_vm = vm;
(*j_vm)->GetEnv(j_vm, (void**) &j_env, JNI_VERSION_1_6);
j_cls = (*j_env)->FindClass(j_env, "<package_name>/<class_name>");
android_call = (*j_env)->GetMethodID(j_env, j_cls, "callFromNDK", "()V");
j_obj = (*j_env)->NewGlobalRef(j_env, (*j_env)->NewObject(j_env, j_cls, android_call));
return JNI_VERSION_1_6;
}
void JNI_OnUnload(JavaVM *vm, void *reserved) {
(*j_env)->DeleteGlobalRef(j_env, j_obj);
}
void *thread_function(void *ptr) {
int *which = (int *) ptr;
(*j_vm)->AttachCurrentThread(j_vm, &j_env, NULL);
int rc;
while (!stop_thread) {
rc = pthread_mutex_lock(&mtx);
rc = pthread_cond_wait(&cond, &mtx);
rc = pthread_mutex_unlock(&mtx);
if (!stop_thread) {
(*j_env)->CallVoidMethod(j_env, j_obj, android_call);
}
}
(*j_vm)->DetachCurrentThread(j_vm);
return NULL;
}
答案 0 :(得分：0)
您是否尝试在模拟器中运行它？由于它在libdvm中崩溃，你可能会在本机崩溃之前获得一些非常有用的日志记录。
问题可能是以下几行：
j_cls = (*j_env)->FindClass(j_env, "<package_name>/<class_name>");
假设您使用实际的命名空间和类名替换"<package_name>/<class_name>"是否安全？
答案 1 :(得分：0)
通过观察，我看到此代码中有三个错误，但使用CheckJNI（http://android-developers.blogspot.com/2011/07/debugging-android-jni-with-checkjni.html）运行，Dalvik应该告诉你做错了什么。 （您应该使用最新版本进行最佳检查。我注意到的一个错误将不会被Gingerbread发现[并且您将在Gingerbread中躲过它]。）
开发和调试时应始终使用CheckJNI。在发布包含单词JNI的任何问题之前，StackOverflow可能应该让人们检查“是的，我尝试过CheckJNI”框： - ）