Priklady: c++/jvm-jni-starter/jvm-jni-starter.cpp@d6614ad97bed

     1 #include <cstdlib>

     2 #include <wchar.h>

     3 #include <locale.h>

     4 #include <string>

     6 #include <jni.h>

     8 using namespace std;

    10 /**

    11  * Spouští JVM z C++, volá statickou metodu ze standardní knihovny (System.currentTimeMillis()) a main() metodu programu SQL-DK

    12  *

    13  * @param argc

    14  * @param argv

    15  * @return

    16  */

    17 int main(int argc, char** argv) {

    19 	setlocale(LC_ALL, "");

    21 	JavaVM *jvm;

    22 	JNIEnv *env;

    24 	JavaVMOption options[1];

    25 	char * home = getenv("HOME");

    27 	string classPath;

    28 	classPath.append("-Djava.class.path=");

    29 	classPath.append(home);

    30 	classPath.append("/projekty/SQL-DK/sql-dk/java/sql-dk/dist/sql-dk.jar");

    31 	classPath.append(":");

    32 	classPath.append(home);

    33 	classPath.append("/projekty/SQL-DK/sql-dk/java/jdbc-loopback-driver/dist/jdbc-loopback-driver.jar");

    35 	wprintf(L"classPath: %s\n", classPath.c_str());

    37 	options[0].optionString = new char[classPath.length() + 1];

    38 	copy(classPath.begin(), classPath.end(), options[0].optionString);

    40 	JavaVMInitArgs vm_args;

    41 	vm_args.version = JNI_VERSION_1_8;

    42 	vm_args.nOptions = 1;

    43 	vm_args.options = options;

    44 	vm_args.ignoreUnrecognized = false;

    46 	JNI_CreateJavaVM(&jvm, (void**) &env, &vm_args);

    48 	string className = "java/lang/System";

    50 	jclass cls = env->FindClass(className.c_str());

    51 	if (cls) {

    52 		string methodName = "currentTimeMillis";

    53 		jmethodID mid = env->GetStaticMethodID(cls, methodName.c_str(), "()J");

    55 		if (mid) {

    56 			jlong time = env->CallStaticLongMethod(cls, mid);

    57 			wprintf(L"Aktuální čas Javy: %d\n", time);

    59 		} else {

    60 			wprintf(L"Metoda nebyla nalezena: %s\n", methodName.c_str());

    61 		}

    62 	} else {

    63 		wprintf(L"Třída nebyla nalezena: %s\n", className.c_str());

    64 	}

    66 	delete cls; // TODO: jak čistit?

    68 	className = "info/globalcode/sql/dk/CLIStarter";

    69 	cls = env->FindClass(className.c_str());

    70 	if (cls) {

    71 		string methodName = "main";

    72 		jmethodID mid = env->GetStaticMethodID(cls, methodName.c_str(), "([Ljava/lang/String;)V");

    74 		if (mid) {

    75 			//jstring arg = env->NewStringUTF("--list-databases");

    76 			//jarray args = env->NewObjectArray(1, env->FindClass("java/lang/String"), arg);

    78 			jobjectArray args = env->NewObjectArray(10, env->FindClass("java/lang/String"), NULL);

    79 			int a = 0;

    80 			env->SetObjectArrayElement(args, a++, env->NewStringUTF("--db"));

    81 			env->SetObjectArrayElement(args, a++, env->NewStringUTF("loopback"));

    82 			//env->SetObjectArrayElement(args, a++, env->NewStringUTF("--sql-in")); // vyžaduje (libovolná) data na standardním vstupu

    83 			env->SetObjectArrayElement(args, a++, env->NewStringUTF("--sql"));

    84 			env->SetObjectArrayElement(args, a++, env->NewStringUTF("…"));

    85 			env->SetObjectArrayElement(args, a++, env->NewStringUTF("--data"));

    86 			env->SetObjectArrayElement(args, a++, env->NewStringUTF("2"));

    87 			env->SetObjectArrayElement(args, a++, env->NewStringUTF("a"));

    88 			env->SetObjectArrayElement(args, a++, env->NewStringUTF("b"));

    89 			env->SetObjectArrayElement(args, a++, env->NewStringUTF("c"));

    90 			env->SetObjectArrayElement(args, a++, env->NewStringUTF("d"));

    93 			for (int i = 0; i < 10; i++) {

    94 				env->CallStaticVoidMethod(cls, mid, args);

    95 				// FIXME: nefuguje – JVM ukončí proces → vlákna/procesy

    96 			}

    99 		} else {

   100 			wprintf(L"Metoda nebyla nalezena: %s\n", methodName.c_str());

   101 		}

   102 	} else {

   103 		wprintf(L"Třída nebyla nalezena: %s\n", className.c_str());

   104 	}

   106 	jvm->DestroyJavaVM();

   107 	return 0;

   108 }

author	František Kučera <franta-hg@frantovo.cz>
	Fri, 15 May 2020 20:32:37 +0200
changeset 59	d6614ad97bed
parent 56	813b44590d07
permissions	-rw-r--r--