安卓调试JNI_OnLoad

先查看包名，然后以调试的模式启动程序

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./adb shell am monitor  # 查看当前活动对象包名（quit结束监控）

abd shell am start -D 包名/.入口

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然后当我们IDA 打开某个so附加上去之后，程序还是处在等待调试的状态

IDA调试选项选中 Suspend on library load/unload

我们用jdb使程序运行起来

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adb forward tcp:8700 jdwp:<pid>  
jdb -connect com.sun.jdi.SocketAttach:hostname=127.0.0.1,port=8700

这样如果在JNI_ONLOAD下断点的话，程序就可以断下来了

下面是一个简单的动态注册native的示例

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public class TextJni {

    static {
        System.loadLibrary("textjni_lib");
    }

    native int text(String message);

    static native int static_text(String message);
}
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#include <jni.h>
#include <string>
#include <android/log.h>

jint native_text(JNIEnv *env, jobject jobject1, jstring msg) {
    const char *p_msg = env->GetStringUTFChars(msg, JNI_FALSE);
    __android_log_print(ANDROID_LOG_INFO, "mmm", "method = %s, msg = %s", __FUNCTION__, p_msg);

    return 0;
}

jint native_staic_text(JNIEnv *env, jobject jclass1, jstring meg) {
    const char *p_msg = env->GetStringUTFChars(meg, JNI_FALSE);
    __android_log_print(ANDROID_LOG_INFO, "mmm", "method = %s, msg = %s", __FUNCTION__, p_msg);

    return 0;
}


static const JNINativeMethod nativeMethod[] = {
        {"text",        "(Ljava/lang/String;)I", (void *) native_text},
        {"static_text", "(Ljava/lang/String;)I", (void *) native_staic_text}
};

static int registNativeMethod(JNIEnv *env) {
    int result = -1;

    jclass class_text = env->FindClass("com.text.ndk1.TextJni");
    if (env->RegisterNatives(class_text, nativeMethod,
                             sizeof(nativeMethod) / sizeof(nativeMethod[0])) == JNI_OK) {
        result = 0;
    }
    return result;
}

jint JNI_OnLoad(JavaVM *vm, void *reserved) {
    JNIEnv *env = NULL;
    int result = -1;

    if (vm->GetEnv((void **) &env, JNI_VERSION_1_1) == JNI_OK) {
        if (registNativeMethod(env) == JNI_OK) {
            result = JNI_VERSION_1_6;
        }
        return result;
    }
}

调用

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public class MainActivity extends AppCompatActivity {

    // Used to load the 'native-lib' library on application startup.
    static {
        System.loadLibrary("native-lib");
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        TextJni.static_text("我是静态方法，哈哈");
        new TextJni().text("我是普通方法，哈哈");
    }  
}