Jni 类型转换接口

1、JString char*互相转化

char* JstringToChar(JNIEnv* env, jstring jstr)
{
        char* rtn = NULL;
        jclass clsstring = env->FindClass("java/lang/String");
        jstring strencode = env->NewStringUTF("utf-8");
        jmethodID mid = env->GetMethodID(clsstring, "getBytes", "(Ljava/lang/String;)[B");
        jbyteArray barr= (jbyteArray)env->CallObjectMethod(jstr, mid, strencode);
        jsize alen = env->GetArrayLength(barr);
        jbyte* ba = env->GetByteArrayElements(barr, JNI_FALSE);
        if (alen > 0)
        {
                rtn = new char[alen+1];
                memcpy(rtn, ba, alen);
                rtn[alen] = 0;
        }
        env->ReleaseByteArrayElements(barr, ba, 0);
        return rtn;
}

jstring CharToJstring(JNIEnv* env, const char* pat)
{
        jclass strClass = env->FindClass("Ljava/lang/String;");
        jmethodID ctorID = env->GetMethodID(strClass, "<init>", "([BLjava/lang/String;)V");
        jbyteArray bytes = env->NewByteArray(strlen(pat));
        env->SetByteArrayRegion(bytes, 0, strlen(pat), (jbyte*)pat);
        jstring encoding = env->NewStringUTF("utf-8");
        return (jstring)env->NewObject(strClass, ctorID, bytes, encoding);
}