尝试访问本机库目录时出错

Question

我正在尝试访问 getPackageManager.getApplicationInfo in jni.

const char* getNativeLibPath(JNIEnv* env, jobject thiz, const char* libraryName, const char* packageName) {
jclass contextClass = env->GetObjectClass(thiz);
jmethodID getPackageManager = env->GetMethodID(contextClass, "getPackageManager", "()Landroid/content/pm/PackageManager;");
jobject instantiatePackageManager = env->CallObjectMethod(thiz, getPackageManager);
jclass packageManagerClass = env->GetObjectClass(instantiatePackageManager);
jmethodID getApplicationInfo = env->GetMethodID(packageManagerClass, "getApplicationInfo", "(Ljava/lang/String;I)Landroid/content/pm/ApplicationInfo;");
jobject instantiateApplicationInfo = env->CallObjectMethod(thiz, getApplicationInfo, packageName, 0);
jclass applicationInfoClass = env->GetObjectClass(instantiateApplicationInfo);
jfieldID nativeLibraryDir = env->GetFieldID(applicationInfoClass, "nativeLibraryDir", "Ljava/lang/String;");
auto string = (jstring) env->GetObjectField(instantiateApplicationInfo, nativeLibraryDir);
const char* returnValue = env->GetStringUTFChars(string, nullptr);
std::string appendedResult = std::string(returnValue) + std::string("/") + std::string(libraryName);
return appendedResult.c_str();
}

这是我的代码。但是由于某种原因，我收到此错误：JNI ERROR (app bug): accessed stale WeakGlobal 0x74eecd21ff (index 1324143135 in a table of size 38) JNI DETECTED ERROR IN APPLICATION: use of deleted weak global reference 0x74eecd21ff任何帮助不胜感激！

Answer 1

您的代码至少存在三个问题：

1. 您使用需要 Java 字符串的const char *调用getApplicationInfo：

jobject instantiateApplicationInfo = env->CallObjectMethod(instantiatePackageManager, getApplicationInfo, env->NewStringUTF(packageName), 0);

2. 你需要调用env->ReleaseStringUTF(returnValue)来释放 Java 端的字符串

3. 您不能返回这样的const char *。要么直接返回std::string，要么使用new char[]分配内存并让调用方释放它。