通过JNI实现C++调用java编写的Alien RFID的程序

// Demo2.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include "windows.h"  
#include <string>  
#include <iostream> 


using  namespace std; 
string jstring2str(JNIEnv* env, jstring jstr);
string  JStringToCString (JNIEnv *env, jstring str);
char* result=NULL;

///
string js2s(JNIEnv* env, jstring jstr){
    jclass clsstring = (env)->FindClass("java/lang/String" ); 
    jstring strencode = (env)->NewStringUTF( "utf-8"); 
    jmethodID mid = (env)->GetMethodID(clsstring,"getBytes","(Ljava/lang/String;)[B");
    if(mid==0){
        cout<<"getBytes method failure......"<<endl;
        return "";
    }
    const char* strCIn = (env)->GetStringUTFChars(jstr,NULL);
    string s(strCIn);
    (env)->ReleaseStringUTFChars(jstr , strCIn);
    return s;
}

int  main() { 
 
  JavaVMOption options[1];
  JNIEnv *env; 
  JavaVM *jvm; 
  JavaVMInitArgs vm_args; 
  long status; 
  jclass cls; 
  jmethodID mid; 
  jint square; 
  jboolean not ; 
  jobject jobj; 

   //////////"-Djava.class.path=.;D:\\;D:/AlienRFID.jar"中“D:\\”指的是要调用的java的类文件所在的路径，“D:/AlienRFID.jar”用于指定第三方jar文件的路径
  options[0].optionString = "-Djava.class.path=.;D:\\;D:/AlienRFID.jar"; /////***很重要呀。。。。
 
  vm_args.version = JNI_VERSION_1_4; 
  vm_args.nOptions = 1; 
  vm_args.options = options; 
  
  status = JNI_CreateJavaVM(&jvm, ( void**)&env, &vm_args); 
  if (status != JNI_ERR) { 
      cout << "create javaVM" << std::endl;    ////可以创建虚拟机
      cls = env->FindClass( "ReadWrite");   ///这里失败了
    if (cls !=0) { 
        cout << "get class" << std::endl; 
    
        ///开始java的线程
      mid = env->GetStaticMethodID(cls, "startListening" , "()V"); 
      if (mid !=0) { 
          cout << "get send method" << std::endl; 
          env->CallStaticIntMethod(cls, mid); 
      }
      mid = env->GetStaticMethodID(cls,  "getTagData" , "()Ljava/lang/String;" ); 
      if (mid !=0) { 
          cout<<"getMessage method"<<endl;
          string temp("hello");
          string  last("");
          while(true){
            jstring message = (jstring)env->CallStaticObjectMethod(cls,mid);
            if(message != NULL){
                //last = jstring2str(env,message);
                last = js2s(env,message);
                if(last!=temp){
                    temp = last;
                    std::cout <<"--------"<<last<<"==="<< std::endl;
                }
                //m_threadSleep(2,0);
            }else{
                std::cout <<"--------message=NULL----"<< std::endl;
            }
          }
      }//*/
    }
    jvm->DestroyJavaVM(); 
    cout<<"success destory java VM"<<endl;
    int i;
    cin>>i;
    return 0; 
  } else {
      cout<<"fail destory java VM"<<endl;
      int j;
    cin>>j;
    return -1; 
  }
}