通过jstringTostring函数，可将Android端用户输入的信息通过JNI传送到本地函数，进行socket传输，以达到Android应用之间的通信。

//jstring to uint8_t*

uint8_t* jstringTostring(JNIEnv* env, jstring jstr)

{

uint8_t* 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 = (uint8_t*)malloc(alen + 1);

memcpy(rtn, ba, alen);

rtn[alen] = 0;

}

env->ReleaseByteArrayElements(barr, ba, 0);

return rtn;

}

//uint8_t* to jstring

jstring stoJstring(JNIEnv* env, const uint8_t* pat)

{

jclass strClass = env->FindClass("Ljava/lang/String;");

jmethodID ctorID = env->GetMethodID(strClass, "", "([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);

}

//invoke function  jstringTostring

static jint SendMessage(JNIEnv* env, jobject thiz, jstring str){

int ret = -1;

uint8_t *send_msg = NULL;

uint8_t *send_frame = NULL;

size_t framelen = 10;

send_msg = jstringTostring(env,str);

send_frame = Set_UserFrame(0x11,send_msg,10);

ret = send_to_all(send_frame,0x11,framelen);

if(ret > 0)

return IPP_SUCCESS;

else

return IPP_SOCKET_ERROR;

}