android jni java类型与c语言类型互换

1.java String转换 C str

char*   Jstring2CStr(JNIEnv*   env,   jstring   jstr)
{
     char*   rtn   =   NULL;
     jclass   clsstring   =   (*env)->FindClass(env,"java/lang/String");
     jstring   strencode   =   (*env)->NewStringUTF(env,"GB2312");
     jmethodID   mid   =   (*env)->GetMethodID(env,clsstring,   "getBytes",   "(Ljava/lang/String;)[B");
     jbyteArray   barr=   (jbyteArray)(*env)->CallObjectMethod(env,jstr,mid,strencode); // String .getByte("GB2312");
     jsize   alen   =   (*env)->GetArrayLength(env,barr);
     jbyte*   ba   =   (*env)->GetByteArrayElements(env,barr,JNI_FALSE);
     if(alen   >   0)
     {
      rtn   =   (char*)malloc(alen+1);         //"\0"
      memcpy(rtn,ba,alen);
      rtn[alen]=0;
     }
     (*env)->ReleaseByteArrayElements(env,barr,ba,0);  //
     return rtn;
}

2.传入参数 int数组jintArray jarray

int length=(*env)->GetArrayLength(env,jarray);
int* array=(*env)->GetIntArrayElements(env,jarray,0);