我尝试使用Android NDK，我的第一个测试不是很确定，我需要帮助，因为我看不出我的错误在哪里。
以下代码编译没有问题，但是当在模拟器上运行时，程序返回SIGSEGV信号，并且没有在logcat中显式写入错误。 但是，会出现一条警告，指示未找到Java类。经过一天对这个问题的研究，一切看起来都是正确的。
这是我的Java代码：JNITestActivity.java
package com.test.jnitest;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
public class JNITestActivity extends Activity {
private static String LIB_NAME = "JNItest";
static {
System.loadLibrary(LIB_NAME);
}
public static native void javaCallJNI();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Log.i("onCreate", "Native function begining");
javaCallJNI();
Log.i("onCreate", "Native function ending");
}
void callFromCPP() {
Log.i("callFromCPP", "JNI can call JAVA !");
return ;
}
}
这是我的C ++代码：testjni.cpp
#include <jni.h>
#include <android/log.h>
#define LOG_TAG "testjni"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
extern "C" {
JNIEXPORT void JNICALL Java_com_test_jnitest_JNITestActivity_javaCallJNI(JNIEnv* env, jobject obj);
};
jint JNI_OnLoad(JavaVM* vm, void* reserved)
{
JNIEnv* env;
if (vm->GetEnv((void**) &env, JNI_VERSION_1_6) != JNI_OK)
return -1;
LOGI("JNI INIT");
return JNI_VERSION_1_6;
}
JNIEXPORT void JNICALL Java_com_test_jnitest_JNITestActivity_javaCallJNI(JNIEnv* env, jobject obj)
{
LOGI("JNI work !");
jclass clazz = env->FindClass("com/test/jnitest/JNITestActivity");
if (clazz == 0) {
LOGI("FindClass error");
return;
}
jmethodID javamethod = env->GetMethodID(clazz, "callFromCPP", "()V");
if (javamethod == 0) {
LOGI("GetMethodID error");
return;
}
env->CallVoidMethod(obj, javamethod);
}
这是我的Makefile：Android.mk
LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := libJNItest
LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog
LOCAL_SRC_FILES := \
src/testjni.cpp
include $(BUILD_SHARED_LIBRARY)
include $(CLEAR_VARS)
和logcat错误：
INFO/testjni(9387): JNI INIT
07-05 15:35:16.993: INFO/onCreate(9387): Native function begining
07-05 15:35:16.993: INFO/testjni(9387): JNI work !
07-05 15:35:17.003: WARN/dalvikvm(9387): JNI WARNING: can't call Lcom/test/jnitest/JNITestActivity;.callFromCPP on instance of Ljava/lang/Class;
07-05 15:35:17.003: INFO/dalvikvm(9387): "main" prio=5 tid=1 RUNNABLE
07-05 15:35:17.018: INFO/dalvikvm(9387): | group="main" sCount=0 dsCount=0 obj=0x4001f1a8 self=0xce48
07-05 15:35:17.018: INFO/dalvikvm(9387): | sysTid=9387 nice=0 sched=0/0 cgrp=default handle=-1345006528
07-05 15:35:17.023: INFO/dalvikvm(9387): | schedstat=( 219631994 557413541 53 )
07-05 15:35:17.023: INFO/dalvikvm(9387): at com.test.jnitest.JNITestActivity.javaCallJNI(Native Method)
07-05 15:35:17.023: INFO/dalvikvm(9387): at com.test.jnitest.JNITestActivity.onCreate(JNITestActivity.java:23)
07-05 15:35:17.023: INFO/dalvikvm(9387): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
07-05 15:35:17.048: INFO/dalvikvm(9387): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
07-05 15:35:17.053: INFO/dalvikvm(9387): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
07-05 15:35:17.053: INFO/dalvikvm(9387): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
07-05 15:35:17.053: INFO/dalvikvm(9387): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
07-05 15:35:17.053: INFO/dalvikvm(9387): at android.os.Handler.dispatchMessage(Handler.java:99)
07-05 15:35:17.053: INFO/dalvikvm(9387): at android.os.Looper.loop(Looper.java:123)
07-05 15:35:17.053: INFO/dalvikvm(9387): at android.app.ActivityThread.main(ActivityThread.java:3683)
07-05 15:35:17.053: INFO/dalvikvm(9387): at java.lang.reflect.Method.invokeNative(Native Method)
07-05 15:35:17.053: INFO/dalvikvm(9387): at java.lang.reflect.Method.invoke(Method.java:507)
07-05 15:35:17.053: INFO/dalvikvm(9387): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
07-05 15:35:17.053: INFO/dalvikvm(9387): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
07-05 15:35:17.053: INFO/dalvikvm(9387): at dalvik.system.NativeStart.main(Native Method)
07-05 15:35:17.053: ERROR/dalvikvm(9387): VM aborting
07-05 15:35:17.163: INFO/DEBUG(31): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
07-05 15:35:17.163: INFO/DEBUG(31): Build fingerprint: 'generic/sdk/generic:2.3.3/GRI34/101070:eng/test-keys'
07-05 15:35:17.163: INFO/DEBUG(31): pid: 9387, tid: 9387 >>> com.test.jnitest <<<
07-05 15:35:17.173: INFO/DEBUG(31): signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr deadd00d
07-05 15:35:17.173: INFO/DEBUG(31): r0 fffffec4 r1 deadd00d r2 00000026 r3 00000000
07-05 15:35:17.183: INFO/DEBUG(31): r4 800a45c0 r5 40517438 r6 41ad8ad0 r7 40517438
07-05 15:35:17.183: INFO/DEBUG(31): r8 befc3428 r9 418fccdc 10 418fccc8 fp 42598bb8
07-05 15:35:17.193: INFO/DEBUG(31): ip 800a4720 sp befc3398 lr afd19375 pc 80045a4a cpsr 20000030
07-05 15:35:17.453: INFO/DEBUG(31): #00 pc 00045a4a /system/lib/libdvm.so
07-05 15:35:17.453: INFO/DEBUG(31): #01 pc 00037748 /system/lib/libdvm.so
07-05 15:35:17.463: INFO/DEBUG(31): #02 pc 0003dc44 /system/lib/libdvm.so
07-05 15:35:17.473: INFO/DEBUG(31): #03 pc 0003fa9c /system/lib/libdvm.so
07-05 15:35:17.473: INFO/DEBUG(31): #04 pc 000003f2 /data/data/com.test.jnitest/lib/libJNItest.so
07-05 15:35:17.473: INFO/DEBUG(31): #05 pc 00000440 /data/data/com.test.jnitest/lib/libJNItest.so
07-05 15:35:17.473: INFO/DEBUG(31): #06 pc 00017d74 /system/lib/libdvm.so
07-05 15:35:17.483: INFO/DEBUG(31): #07 pc 00048ecc /system/lib/libdvm.so
07-05 15:35:17.493: INFO/DEBUG(31): #08 pc 00041a86 /system/lib/libdvm.so
07-05 15:35:17.493: INFO/DEBUG(31): #09 pc 0004e624 /system/lib/libdvm.so
07-05 15:35:17.503: INFO/DEBUG(31): #10 pc 0001cfd4 /system/lib/libdvm.so
07-05 15:35:17.503: INFO/DEBUG(31): #11 pc 000220dc /system/lib/libdvm.so
07-05 15:35:17.503: INFO/DEBUG(31): #12 pc 00020fd0 /system/lib/libdvm.so
07-05 15:35:17.523: INFO/DEBUG(31): #13 pc 0005f5de /system/lib/libdvm.so
07-05 15:35:17.523: INFO/DEBUG(31): #14 pc 00066fce /system/lib/libdvm.so
07-05 15:35:17.523: INFO/DEBUG(31): #15 pc 0001cfd4 /system/lib/libdvm.so
07-05 15:35:17.533: INFO/DEBUG(31): #16 pc 000220dc /system/lib/libdvm.so
07-05 15:35:17.543: INFO/DEBUG(31): #17 pc 00020fd0 /system/lib/libdvm.so
07-05 15:35:17.543: INFO/DEBUG(31): #18 pc 0005f430 /system/lib/libdvm.so
07-05 15:35:17.553: INFO/DEBUG(31): #19 pc 0004b9a8 /system/lib/libdvm.so
07-05 15:35:17.553: INFO/DEBUG(31): #20 pc 0003ebb0 /system/lib/libdvm.so
07-05 15:35:17.563: INFO/DEBUG(31): #21 pc 000314ac /system/lib/libandroid_runtime.so
07-05 15:35:17.573: INFO/DEBUG(31): #22 pc 000322c6 /system/lib/libandroid_runtime.so
07-05 15:35:17.573: INFO/DEBUG(31): #23 pc 00008ca2 /system/bin/app_process
07-05 15:35:17.573: INFO/DEBUG(31): #24 pc 00014db8 /system/lib/libc.so
07-05 15:35:17.573: INFO/DEBUG(31): code around pc:
07-05 15:35:17.583: INFO/DEBUG(31): 80045a28 447a4479 ed0cf7d1 20004c09 ee34f7d1
07-05 15:35:17.583: INFO/DEBUG(31): 80045a38 447c4808 6bdb5823 d0002b00 49064798
07-05 15:35:17.593: INFO/DEBUG(31): 80045a48 700a2226 eea0f7d1 000436b7 00045275
07-05 15:35:17.593: INFO/DEBUG(31): 80045a58 0005eb82 fffffec4 deadd00d b510b40e
07-05 15:35:17.604: INFO/DEBUG(31): 80045a68 4c0a4b09 447bb083 aa05591b 6b5bca02
07-05 15:35:17.604: INFO/DEBUG(31): code around lr:
07-05 15:35:17.633: INFO/DEBUG(31): afd19354 b0834a0d 589c447b 26009001 686768a5
07-05 15:35:17.633: INFO/DEBUG(31): afd19364 220ce008 2b005eab 1c28d003 47889901
07-05 15:35:17.633: INFO/DEBUG(31): afd19374 35544306 d5f43f01 2c006824 b003d1ee
07-05 15:35:17.633: INFO/DEBUG(31): afd19384 bdf01c30 000281a8 ffffff88 1c0fb5f0
07-05 15:35:17.643: INFO/DEBUG(31): afd19394 43551c3d a904b087 1c16ac01 604d9004
07-05 15:35:17.643: INFO/DEBUG(31): stack:
07-05 15:35:17.643: INFO/DEBUG(31): befc3358 00000015
07-05 15:35:17.643: INFO/DEBUG(31): befc335c afd18407 /system/lib/libc.so
07-05 15:35:17.653: INFO/DEBUG(31): befc3360 afd4270c /system/lib/libc.so
07-05 15:35:17.653: INFO/DEBUG(31): befc3364 afd426b8 /system/lib/libc.so
07-05 15:35:17.653: INFO/DEBUG(31): befc3368 00000000
07-05 15:35:17.653: INFO/DEBUG(31): befc336c afd19375 /system/lib/libc.so
07-05 15:35:17.653: INFO/DEBUG(31): befc3370 0000ce48 [heap]
07-05 15:35:17.663: INFO/DEBUG(31): befc3374 afd183d9 /system/lib/libc.so
07-05 15:35:17.663: INFO/DEBUG(31): befc3378 40517438 /dev/ashmem/dalvik-heap (deleted)
07-05 15:35:17.673: INFO/DEBUG(31): befc337c 0005eb82 [heap]
07-05 15:35:17.673: INFO/DEBUG(31): befc3380 40517438 /dev/ashmem/dalvik-heap (deleted)
07-05 15:35:17.673: INFO/DEBUG(31): befc3384 41ad8ad0 /dev/ashmem/dalvik-LinearAlloc (deleted)
07-05 15:35:17.673: INFO/DEBUG(31): befc3388 40517438 /dev/ashmem/dalvik-heap (deleted)
07-05 15:35:17.673: INFO/DEBUG(31): befc338c afd18437 /system/lib/libc.so
07-05 15:35:17.673: INFO/DEBUG(31): befc3390 df002777
07-05 15:35:17.673: INFO/DEBUG(31): befc3394 e3a070ad
07-05 15:35:17.673: INFO/DEBUG(31): #00 befc3398 40009328 /dev/ashmem/dalvik-heap (deleted)
07-05 15:35:17.683: INFO/DEBUG(31): befc339c 8003774d /system/lib/libdvm.so
07-05 15:35:17.683: INFO/DEBUG(31): #01 befc33a0 40009328 /dev/ashmem/dalvik-heap (deleted)
07-05 15:35:17.693: INFO/DEBUG(31): befc33a4 8003dc49 /system/lib/libdvm.so
07-05 15:35:19.693: DEBUG/Zygote(33): Process 9387 terminated by signal (11)
07-05 15:35:19.713: INFO/ActivityManager(74): Process com.test.jnitest (pid 9387) has died.
谢谢你， 克里斯托弗。
答案 0 :(得分：21)
因为这个错误而失去了一天后，我终于找到了问题的解决方案：
函数javaCallJNI()在Java中声明为静态本机，但静态方法不能调用非静态方法...
要解决此问题，只需替换：
public static native void javaCallJNI();
通过
public native void javaCallJNI();
在JNITestActivity.java中
感谢您的帮助，很快就会看到;）
答案 1 :(得分：4)
你有什么看起来对我好...但你可能会尝试更换
jclass clazz = env->FindClass("com/test/jnitest/JNITestActivity");
使用
jclass clazz = env->GetObjectClass(obj);