c语言调用java类

剑客一直说我写的blog属于阳春白雪，很少有人看懂，以后尽量向大家灌输一些基础知识。c语言通过jvm环境可以调用java类，我以前的blog写过。http://blogger.org.cn/blog/more.asp?name=hongrui&id=25509只是新的版本发生了一点变化，没有JDK1_1InitArgs的定义，详见bug，http://bugs.sun.com/view_bug.do?bug_id=5031222不在需要调用JNI_GetDefaultJavaVMInitArgs。先写java类，import java.awt.*;import java.awt.event.*;public class MyApp2 extends Frame{    public MyApp2()    {        super( "My Java App" );        add( new Label("Hello, world!") );    }    public static void main( String[] args )    {        MyApp2 frame = new MyApp2();        frame.addWindowListener( new WindowAdapter()        {            public void windowClosing(WindowEvent e) {System.exit(0);}        });        frame.setSize(200,200);        frame.setVisible(true);    }}编译为jar后，运行java -cp ./app.jar MyApp2调用的java的c程序#include#ifdef _WIN32#define PATH_SEPARATOR ';'#else /* UNIX */#define PATH_SEPARATOR ':'#endif#define USER_CLASSPATH "." /* where Prog.class is */#define MAIN_CLASS  "MyApp2"#pragma comment(lib,"jvm.lib")int main(){    JNIEnv *env;    JavaVM *jvm;    jint res;    jclass cls;    jmethodID mid;    jstring jstr;    jobjectArray args;    char classpath[1024];    JavaVMInitArgs vm_args;    JavaVMOption options[4];    /* disable JIT */    options[0].optionString = "-Djava.compiler=NONE";    /* user classes */    options[1].optionString = "-Djava.library.path=.";    /*native library path*/    options[2].optionString = "-Djava.class.path=D:\\idea\\gui\\out\\artifacts\\app\\app.jar";    /* print JNI-related messages */    //options[3].optionString = "-verbose:jni"; options[3].optionString = "-verbose";     vm_args.version = JNI_VERSION_1_6;     vm_args.options = options;     vm_args.nOptions = 4;     vm_args.ignoreUnrecognized = JNI_TRUE;     /* Note that in the Java 2 SDK, there is no longer any need to call      * JNI_GetDefaultJavaVMInitArgs.      */    /* Append USER_CLASSPATH to the end of default system class path */     /*      sprintf(classpath, "%s%c%s", */     /*              vm_args.classpath, PATH_SEPARATOR, USER_CLASSPATH); */     /*      vm_args.classpath = classpath; */    /* Create the Java VM */     res = JNI_CreateJavaVM(&jvm, (void **)&env, &vm_args);     if (res       fprintf(stderr,"ERROR creat JVM failed resultcode=%d\n",res);       exit(1);D:\Java\jdk1.7.0_03\jre\bin\client     }    cls = (*env)->FindClass(env, MAIN_CLASS);    if (cls == 0) {        fprintf(stderr, "Can't find Prog class\n");        exit(1);    }     mid = (*env)->GetStaticMethodID(env, cls, "main", "([Ljava/lang/String;)V");    if (mid == 0) {        fprintf(stderr, "Can't find Prog.main\n");        exit(1);    }    jstr = (*env)->NewStringUTF(env, " from C!");    if (jstr == 0) {        fprintf(stderr, "Out of memory\n");        exit(1);    }    args = (*env)->NewObjectArray(env, 1,                        (*env)->FindClass(env, "java/lang/String"), jstr);    if (args == 0) {        fprintf(stderr, "Out of memory\n");        exit(1);    }    fprintf(stderr,"calling java...\n");    (*env)->CallStaticVoidMethod(env, cls, mid, args);    fprintf(stderr,"returned from java. killing VM.\n");    (*jvm)->DestroyJavaVM(jvm);}然后把编译好的程序，放到D:\Java\jdk1.7.0_03\jre\bin\client目录下，只要是jvm.dll一个目录，然后运行就ok。值得注意的是两个path：classpath 和 java.library.pathclasspath是指向jar包的位置java.library.path是非java类包的位置如（dll,so）经常在LINUX下使用系统变量LD_LIBRARY_PATH来添加java.library.path很少在vm arguments里添加-Djava.library.path= /usr/local/lib