mqtt学习-3 编译运行测试__mqtt交叉编译

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1、按上节第一种配置编译时报错，无法打开文件“paho-mqtt3as.lib” ，主要是没有勾选Static,顺便把SSL也勾选，会更新编译列表选项，

然后再点Configure如果没有错误，红色全部消失、Generate。

2、编译依旧报错,不过已经不影响本次测试了，后面再处理这个问题

严重性代码说明项目文件行禁止显示状态
错误 LNK2019 无法解析的外部符号 OpenSSL_version，函数 MQTTClient_getVersionInfo 中引用了该符号 paho-mqtt3cs I:\mqtt\paho.mqtt.c\build\src\MQTTClient.obj 1

原因是我这里用的openssl版本问题

https://slproweb.com/download/Win64OpenSSL-1_1_1d.exe

设置这个路径

之前自动选择的是C:\OpenSSL-Win32下的lib文件

configure,generate即可解决这个问题

3、测试推送

订阅，修改地址，用户名，密码为mqtt学习-1配置

3.1修改I:\mqtt\paho.mqtt.c\src\samples\MQTTAsync_subscribe.c如下

/*******************************************************************************
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v2.0
 * and Eclipse Distribution License v1.0 which accompany this distribution. 
 * The Eclipse Public License is available at 
 *   https://www.eclipse.org/legal/epl-2.0/
 * and the Eclipse Distribution License is available at 
 *   http://www.eclipse.org/org/documents/edl-v10.php.
 * Contributors:
 *    Ian Craggs - initial contribution
 *******************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "MQTTAsync.h"
#if !defined(_WIN32)
#include <unistd.h>
#else
#include <windows.h>
#endif
#if defined(_WRS_KERNEL)
#include <OsWrapper.h>
#endif
#define ADDRESS     "tcp://127.0.0.1:1883"
#define CLIENTID    "ExampleClientSub"
#define TOPIC       "MQTT Examples"
#define PAYLOAD     "Hello World!"
#define QOS         1
#define TIMEOUT     10000L
int disc_finished = 0;
int subscribed = 0;
int finished = 0;
void connlost(void *context, char *cause)
	MQTTAsync client = (MQTTAsync)context;
	MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
	int rc;
	printf("\nConnection lost\n");
	if (cause)
		printf("     cause: %s\n", cause);
	printf("Reconnecting\n");
	conn_opts.keepAliveInterval = 20;
	conn_opts.cleansession = 1;
	conn_opts.username = "admin";
	conn_opts.password = "password";
	if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS)
		printf("Failed to start connect, return code %d\n", rc);
		finished = 1;
int msgarrvd(void *context, char *topicName, int topicLen, MQTTAsync_message *message)
    printf("Message arrived\n");
    printf("     topic: %s\n", topicName);
    printf("   message: %.*s\n", message->payloadlen, (char*)message->payload);
    MQTTAsync_freeMessage(&message);
    MQTTAsync_free(topicName);
    return 1;
void onDisconnectFailure(void* context, MQTTAsync_failureData* response)
	printf("Disconnect failed, rc %d\n", response->code);
	disc_finished = 1;
void onDisconnect(void* context, MQTTAsync_successData* response)
	printf("Successful disconnection\n");
	disc_finished = 1;
void onSubscribe(void* context, MQTTAsync_successData* response)
	printf("Subscribe succeeded\n");
	subscribed = 1;
void onSubscribeFailure(void* context, MQTTAsync_failureData* response)
	printf("Subscribe failed, rc %d\n", response->code);
	finished = 1;
void onConnectFailure(void* context, MQTTAsync_failureData* response)
	printf("Connect failed, rc %d\n", response->code);
	finished = 1;
void onConnect(void* context, MQTTAsync_successData* response)
	MQTTAsync client = (MQTTAsync)context;
	MQTTAsync_responseOptions opts = MQTTAsync_responseOptions_initializer;
	int rc;
	printf("Successful connection\n");
	printf("Subscribing to topic %s\nfor client %s using QoS%d\n\n"
           "Press Q<Enter> to quit\n\n", TOPIC, CLIENTID, QOS);
	opts.onSuccess = onSubscribe;
	opts.onFailure = onSubscribeFailure;
	opts.context = client;
	if ((rc = MQTTAsync_subscribe(client, TOPIC, QOS, &opts)) != MQTTASYNC_SUCCESS)
		printf("Failed to start subscribe, return code %d\n", rc);
		finished = 1;
int main(int argc, char* argv[])
	MQTTAsync client;
	MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
	MQTTAsync_disconnectOptions disc_opts = MQTTAsync_disconnectOptions_initializer;
	int rc;
	int ch;
	if ((rc = MQTTAsync_create(&client, ADDRESS, CLIENTID, MQTTCLIENT_PERSISTENCE_NONE, NULL))
			!= MQTTASYNC_SUCCESS)
		printf("Failed to create client, return code %d\n", rc);
		rc = EXIT_FAILURE;
		goto exit;
	if ((rc = MQTTAsync_setCallbacks(client, client, connlost, msgarrvd, NULL)) != MQTTASYNC_SUCCESS)
		printf("Failed to set callbacks, return code %d\n", rc);
		rc = EXIT_FAILURE;
		goto destroy_exit;
	conn_opts.keepAliveInterval = 20;
	conn_opts.cleansession = 1;
	conn_opts.onSuccess = onConnect;
	conn_opts.onFailure = onConnectFailure;
	conn_opts.context = client;
	if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS)
		printf("Failed to start connect, return code %d\n", rc);
		rc = EXIT_FAILURE;
		goto destroy_exit;
	while (!subscribed && !finished)
		#if defined(_WIN32)
			Sleep(100);
		#else
			usleep(10000L);
		#endif
	if (finished)
		goto exit;
		ch = getchar();
	} while (ch!='Q' && ch != 'q');
	disc_opts.onSuccess = onDisconnect;
	disc_opts.onFailure = onDisconnectFailure;
	if ((rc = MQTTAsync_disconnect(client, &disc_opts)) != MQTTASYNC_SUCCESS)
		printf("Failed to start disconnect, return code %d\n", rc);
		rc = EXIT_FAILURE;
		goto destroy_exit;
 	while (!disc_finished)
		#if defined(_WIN32)
			Sleep(100);
		#else
			usleep(10000L);
		#endif
destroy_exit:
	MQTTAsync_destroy(&client);
exit:
 	return rc;
3.2修改I:\mqtt\paho.mqtt.c\src\samples\MQTTAsync_publish.c如下
/*******************************************************************************
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v2.0
 * and Eclipse Distribution License v1.0 which accompany this distribution. 
 * The Eclipse Public License is available at 
 *   https://www.eclipse.org/legal/epl-2.0/
 * and the Eclipse Distribution License is available at 
 *   http://www.eclipse.org/org/documents/edl-v10.php.
 * Contributors:
 *    Ian Craggs - initial contribution
 *******************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "MQTTAsync.h"
#if !defined(_WIN32)
#include <unistd.h>
#else
#include <windows.h>
#endif
#if defined(_WRS_KERNEL)
#include <OsWrapper.h>
#endif
#define ADDRESS     "tcp://127.0.0.1:1883"
#define CLIENTID    "ExampleClientPub"
#define TOPIC       "MQTT Examples"
#define PAYLOAD     "Hello World!"
#define QOS         1
#define TIMEOUT     10000L
int finished = 0;
void connlost(void *context, char *cause)
	MQTTAsync client = (MQTTAsync)context;
	MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
	int rc;
	printf("\nConnection lost\n");
	printf("     cause: %s\n", cause);
	printf("Reconnecting\n");
	conn_opts.keepAliveInterval = 20;
	conn_opts.cleansession = 1;
	conn_opts.username = "admin";
	conn_opts.password = "password";
	if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS)
		printf("Failed to start connect, return code %d\n", rc);
 		finished = 1;
void onDisconnectFailure(void* context, MQTTAsync_failureData* response)
	printf("Disconnect failed\n");
	finished = 1;
void onDisconnect(void* context, MQTTAsync_successData* response)
	printf("Successful disconnection\n");
	finished = 1;
void onSendFailure(void* context, MQTTAsync_failureData* response)
	MQTTAsync client = (MQTTAsync)context;
	MQTTAsync_disconnectOptions opts = MQTTAsync_disconnectOptions_initializer;
	int rc;
	printf("Message send failed token %d error code %d\n", response->token, response->code);
	opts.onSuccess = onDisconnect;
	opts.onFailure = onDisconnectFailure;
	opts.context = client;
	if ((rc = MQTTAsync_disconnect(client, &opts)) != MQTTASYNC_SUCCESS)
		printf("Failed to start disconnect, return code %d\n", rc);
		exit(EXIT_FAILURE);
void onSend(void* context, MQTTAsync_successData* response)
	MQTTAsync client = (MQTTAsync)context;
	MQTTAsync_disconnectOptions opts = MQTTAsync_disconnectOptions_initializer;
	int rc;
	printf("Message with token value %d delivery confirmed\n", response->token);
	opts.onSuccess = onDisconnect;
	opts.onFailure = onDisconnectFailure;
	opts.context = client;
	if ((rc = MQTTAsync_disconnect(client, &opts)) != MQTTASYNC_SUCCESS)
		printf("Failed to start disconnect, return code %d\n", rc);
		exit(EXIT_FAILURE);
void onConnectFailure(void* context, MQTTAsync_failureData* response)
	printf("Connect failed, rc %d\n", response ? response->code : 0);
	finished = 1;
void onConnect(void* context, MQTTAsync_successData* response)
	MQTTAsync client = (MQTTAsync)context;
	MQTTAsync_responseOptions opts = MQTTAsync_responseOptions_initializer;
	MQTTAsync_message pubmsg = MQTTAsync_message_initializer;
	int rc;
	printf("Successful connection\n");
	opts.onSuccess = onSend;
	opts.onFailure = onSendFailure;
	opts.context = client;
	pubmsg.payload = PAYLOAD;
	pubmsg.payloadlen = (int)strlen(PAYLOAD);
	pubmsg.qos = QOS;
	pubmsg.retained = 0;
	if ((rc = MQTTAsync_sendMessage(client, TOPIC, &pubmsg, &opts)) != MQTTASYNC_SUCCESS)
		printf("Failed to start sendMessage, return code %d\n", rc);
		exit(EXIT_FAILURE);
int messageArrived(void* context, char* topicName, int topicLen, MQTTAsync_message* m)
	/* not expecting any messages */
	return 1;
int main(int argc, char* argv[])
	MQTTAsync client;
	MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
	int rc;
	if ((rc = MQTTAsync_create(&client, ADDRESS, CLIENTID, MQTTCLIENT_PERSISTENCE_NONE, NULL)) != MQTTASYNC_SUCCESS)
		printf("Failed to create client object, return code %d\n", rc);
		exit(EXIT_FAILURE);
	if ((rc = MQTTAsync_setCallbacks(client, NULL, connlost, messageArrived, NULL)) != MQTTASYNC_SUCCESS)
		printf("Failed to set callback, return code %d\n", rc);
		exit(EXIT_FAILURE);
	conn_opts.keepAliveInterval = 20;
	conn_opts.cleansession = 1;
	conn_opts.onSuccess = onConnect;
	conn_opts.onFailure = onConnectFailure;
	conn_opts.context = client;
	if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS)
		printf("Failed to start connect, return code %d\n", rc);
		exit(EXIT_FAILURE);
	printf("Waiting for publication of %s\n"
         "on topic %s for client with ClientID: %s\n",
         PAYLOAD, TOPIC, CLIENTID);
	while (!finished)
		#if defined(_WIN32)
			Sleep(100);
		#else
			usleep(10000L);
		#endif
	MQTTAsync_destroy(&client);
 	return rc;
3.3进入输出目录，将paho-mqtt3a.dll拷贝到Debug目录下
说明运行正常 
        java 浮点数 判断相等
    浮点数之间的等值判断，基本数据类型不能使用 == 进行比较，包装数据类型不能使用 equals 进行判断。说明：浮点数采用“尾数+阶码”的编码方式，类似于科学计数法的“有效数字+指数”的表示方式。二进制无法精确表 示大部分的十进制小数。反例： float a = 1.0F - 0.9F;
float b = 0.9F