library.c : call static method com.statusim.GethService.signalEvent

src/library.c

@@ -0,0 +1,155 @@
+#include <jni.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+
+bool GethServiceSignalEvent( const char *jsonEvent );
+
+static JavaVM *gJavaVM = NULL;
+static jclass JavaClassPtr_GethService = NULL;
+static jmethodID JavaMethodPtr_signalEvent = NULL;
+
+static bool JniLibraryInit( JNIEnv *env );
+
+/*!
+ * @brief Get interface to JNI.
+ * 
+ * @return true if thread should be detached from JNI.
+ */
+static bool JniAttach( JNIEnv **env )
+{
+	jint status;
+	
+	if (gJavaVM == NULL)
+	{
+		env = NULL;
+	}
+	
+	status = (*gJavaVM)->GetEnv( gJavaVM, (void **)env, JNI_VERSION_1_6);
+	if (status == JNI_EDETACHED)
+	{
+		// attach thread to JNI
+		(*gJavaVM)->AttachCurrentThread( gJavaVM, (void **)env, NULL );
+		return false;
+	}
+	else if (status != JNI_OK)
+	{
+		return false;
+	}
+	
+	return true;
+}
+
+/*!
+ * @brief The VM calls JNI_OnLoad when the native library is loaded.
+ */
+JNIEXPORT jint JNI_OnLoad(JavaVM* vm, void* reserved)
+{
+	bool detach;
+	JNIEnv *env;
+	bool result = JNI_VERSION_1_6;
+
+	gJavaVM = vm;
+
+	// attach thread to JNI
+	detach = JniAttach( &env );
+	if (env == NULL)
+	{
+		// failed
+		gJavaVM = NULL;
+		return 0;
+	}
+	
+	if (!JniLibraryInit( env ))
+	{
+		// fail loading of JNI library
+		result = 0;
+	}
+
+	if (detach)
+	{
+		// detach thread from JNI
+		(*gJavaVM)->DetachCurrentThread( gJavaVM );
+	}
+	
+	if (result != JNI_VERSION_1_6)
+	{
+		gJavaVM = NULL;
+	}
+	
+	return result;
+}
+
+/*!
+ * @brief Initialize library.
+ */
+bool JniLibraryInit( JNIEnv *env )
+{
+	int i;
+	
+	JavaClassPtr_GethService = (*env)->FindClass( env, "com/statusim/GethService" );
+	if (JavaClassPtr_GethService == NULL) return false;
+	JavaClassPtr_GethService = (jclass)(*env)->NewGlobalRef( env, JavaClassPtr_GethService );
+	if (JavaClassPtr_GethService == NULL) return false;
+	
+	struct { bool bStatic; jclass classPtr; jmethodID *methodPtr; const char *methodId; const char *params; } javaMethodDescriptors[] =
+	{
+		{ true, JavaClassPtr_GethService, &JavaMethodPtr_signalEvent, 								"signalEvent", 							"(Ljava/lang/String;)V" },
+			
+//		{ false, JavaClassPtr_GethService, 	&JavaMethodPtr_someNonStaticMethod, 						"someNonStaticMethod", 					"(Ljava/lang/String;)V" },
+	};
+
+	for (i = 0; i < sizeof(javaMethodDescriptors) / sizeof(javaMethodDescriptors[0]); i++)
+	{
+		if (javaMethodDescriptors[i].bStatic)
+		{
+			*(javaMethodDescriptors[i].methodPtr) = (*env)->GetStaticMethodID( env, javaMethodDescriptors[i].classPtr, javaMethodDescriptors[i].methodId, javaMethodDescriptors[i].params );
+		}
+		else
+		{
+			*(javaMethodDescriptors[i].methodPtr) = (*env)->GetMethodID( env, javaMethodDescriptors[i].classPtr, javaMethodDescriptors[i].methodId, javaMethodDescriptors[i].params );
+		}
+
+		if (*(javaMethodDescriptors[i].methodPtr) == NULL) return false;
+	}
+	
+	return true;
+}
+
+/*!
+ * @brief Calls static method signalEvent of class com.statusim.GethService.
+ * 
+ * @param jsonEvent - UTF8 string
+ */
+bool GethServiceSignalEvent( const char *jsonEvent )
+{
+	bool detach;
+	JNIEnv *env;
+
+	// attach thread to JNI
+	detach = JniAttach( &env );
+	if (env == NULL)
+	{
+		// failed
+		return false;
+	}
+	
+	jstring javaJsonEvent = NULL;
+	if (jsonEvent != NULL)
+	{
+		javaJsonEvent = (*env)->NewStringUTF( env, jsonEvent );
+	}
+
+	(*env)->CallStaticVoidMethod( env, JavaClassPtr_GethService, JavaMethodPtr_signalEvent, javaJsonEvent );
+
+	if (javaJsonEvent != NULL) (*env)->DeleteLocalRef( env, javaJsonEvent );
+
+	if (detach)
+	{
+		// detach thread from JNI
+		(*gJavaVM)->DetachCurrentThread( gJavaVM );
+	}
+	
+	return true;
+}