#include <stdio.h>
#include <jni.h>
JNIEnv* create_vm() {
JavaVM* jvm;
JNIEnv* env;
JavaVMInitArgs args;
JavaVMOption options[1];
/* There is a new JNI_VERSION_1_4, but it doesn't add anything for the purposes of our example. */
args.version = JNI_VERSION_1_2;
args.nOptions = 1;
options[0].optionString = "-Djava.class.path=/home/test/workspace/pankajs/"
"jikes/JikesRVMia32-linuxproduction/target/tests/stress/prototype/basic/classes";
args.options = options;
args.ignoreUnrecognized = JNI_FALSE;
JNI_CreateJavaVM(&jvm, (void **)&env, &args);
return env;
}
void invoke_class(JNIEnv* env) {
jclass helloWorldClass;
jmethodID mainMethod;
jobjectArray applicationArgs;
jstring applicationArg0;
helloWorldClass = (*env)->FindClass(env, "/test/org/jikesrvm/basic/core/bytecode/TestSwitch");
mainMethod = (*env)->GetStaticMethodID(env, helloWorldClass, "main", "([Ljava/lang/String;)V");
applicationArgs = (*env)->NewObjectArray(env, 1, (*env)->FindClass(env, "java/lang/String"), NULL);
applicationArg0 = (*env)->NewStringUTF(env, "From-C-program");
(*env)->SetObjectArrayElement(env, applicationArgs, 0, applicationArg0);
(*env)->CallStaticVoidMethod(env, helloWorldClass, mainMethod, applicationArgs);
}
int main(int argc, char **argv) {
JNIEnv* env = create_vm();
invoke_class( env );
}
I am trying to learn how JVM is actually invoked from bootstrap C files.
我在互联网上找到了这个例子,我在运行时遇到了一些问题。
据我所知,我正确指定了构建命令,
g++ -g -I /usr/lib/jvm/java-6-sun-1.6.0.26/include -I /usr/lib/jvm/java-6-sun-1.6.0.26/include/linux CallJVM.c
我的意图是使用jikesrvm实际运行它,但我选择了实验 使用JVM。 我得到的错误是:
CallJVM.c: In function ‘JNIEnv* create_vm()’:
CallJVM.c:14:4: warning: deprecated conversion from string constant to ‘char*’
CallJVM.c: In function ‘void invoke_class(JNIEnv*)’:
CallJVM.c:28:26: error: base operand of ‘->’ has non-pointer type ‘JNIEnv’
CallJVM.c:30:21: error: base operand of ‘->’ has non-pointer type ‘JNIEnv’
CallJVM.c:32:26: error: base operand of ‘->’ has non-pointer type ‘JNIEnv’
CallJVM.c:32:57: error: base operand of ‘->’ has non-pointer type ‘JNIEnv’
CallJVM.c:33:26: error: base operand of ‘->’ has non-pointer type ‘JNIEnv’
CallJVM.c:34:8: error: base operand of ‘->’ has non-pointer type ‘JNIEnv’
CallJVM.c:36:8: error: base operand of ‘->’ has non-pointer type ‘JNIEnv’
我注意到在C和C ++中实现的不同方式,但我认为我正在正确地编写它。
编辑:在使用gcc编译时,我正在
undefined reference to `JNI_CreateJavaVM'
这是eclipse中提示的内容,但我认为我的配置不合适。当我使用ctrl+click
时,我也引用了jni.h,但仍然缺少引用的原因?
我在include path上特别提到了我的文件夹。
答案 0 :(得分:76)
我注意到在C和C ++中实现的不同方式,但我认为我正在正确地编写它。
您正在使用C
变体,但正在使用g++
进行编译,C++
会调用.c
编译器(即使您的源文件具有C
扩展名。)< / p>
更改(*env)->FindClass(env, ...)
变种,例如
C++
到env->FindClass(...)
变体,例如
gcc
或将编译器切换到C
以将源代码编译为{{1}}。
答案 1 :(得分:0)
我正在其他SO帖子上找到工作..
我直截了当地使用了这个 - “
gcc -g -I /usr/lib/jvm/java-6-sun-1.6.0.26/include -I /usr/lib/jvm/java-6-sun-1.6.0.26/include/linux -L /usr/lib/jvm/java-6-sun-1.6.0.26/jre/lib/i386/server -ljvm CallJVM.c
和a.out已创建。然后我需要将它与服务器文件夹中的libjvm.so链接,如帖子中所述。
已经提出了一个非常漂亮的解释here