参考代码
https://github.com/eclipse/paho.mqtt.c/blob/master/src/samples/paho_c_sub.c
方法1:
conn_opts.cleanstart = 0;
缺点:
当我把mqtt server 清除数据重新部署后,mqtt client reconnect后,无法自动订阅;
方法2:
conn_opts.cleanstart = 0;
......
while (1)
{
mysleep(1000);
if (finished)
{
MQTTAsync_disconnect(client, &disc_opts);
printf("reconnet\n");
finished = 0;
MQTTAsync_connect(client, &conn_opts);
}
}
完整代码 paho.mqtt.c-master\src\samples\paho_c_sub.c
/*******************************************************************************
* Copyright (c) 2012, 2018 IBM Corp., and others
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* and Eclipse Distribution License v1.0 which accompany this distribution.
*
* The Eclipse Public License is available at
* http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Ian Craggs - initial contribution
* Ian Craggs - fix for bug 413429 - connectionLost not called
* Guilherme Maciel Ferreira - add keep alive option
* Ian Craggs - add full capability
*******************************************************************************/
#include "MQTTAsync.h"
#include "MQTTClientPersistence.h"
#include "pubsub_opts.h"
#include <stdio.h>
#include <signal.h>
#include <string.h>
#include <stdlib.h>
#if defined(WIN32)
#include <windows.h>
#define sleep Sleep
#else
#include <sys/time.h>
#include <unistd.h>
#endif
#if defined(_WRS_KERNEL)
#include <OsWrapper.h>
#endif
volatile int finished = 0;
int subscribed = 0;
int disconnected = 0;
void mysleep(int ms)
{
#if defined(WIN32)
Sleep(ms);
#else
usleep(ms * 1000);
#endif
}
void cfinish(int sig)
{
signal(SIGINT, NULL);
finished = 1;
}
struct pubsub_opts opts =
{
0, 0, 0, 0, "\n", 100, /* debug/app options */
NULL, NULL, 1, 0, 0, /* message options */
MQTTVERSION_DEFAULT, NULL, "paho-c-sub", 0, 0, NULL, NULL, "localhost", "1883", NULL, 10, /* MQTT options */
NULL, NULL, 0, 0, /* will options */
0, NULL, NULL, NULL, NULL, NULL, NULL, /* TLS options */
0, {NULL, NULL}, /* MQTT V5 options */
};
int messageArrived(void *context, char *topicName, int topicLen, MQTTAsync_message *message)
{
size_t delimlen = 0;
if (opts.verbose)
printf("%d %s\t", message->payloadlen, topicName);
if (opts.delimiter)
delimlen = strlen(opts.delimiter);
if (opts.delimiter == NULL || (message->payloadlen > delimlen &&
strncmp(opts.delimiter, &((char*)message->payload)[message->payloadlen - delimlen], delimlen) == 0))
printf("%.*s", message->payloadlen, (char*)message->payload);
else
printf("%.*s%s", message->payloadlen, (char*)message->payload, opts.delimiter);
if (message->struct_version == 1 && opts.verbose)
logProperties(&message->properties);
fflush(stdout);
MQTTAsync_freeMessage(&message);
MQTTAsync_free(topicName);
return 1;
}
void onDisconnect(void* context, MQTTAsync_successData* response)
{
disconnected = 1;
}
void onSubscribe5(void* context, MQTTAsync_successData5* response)
{
subscribed = 1;
}
void onSubscribe(void* context, MQTTAsync_successData* response)
{
subscribed = 1;
}
void onSubscribeFailure5(void* context, MQTTAsync_failureData5* response)
{
if (!opts.quiet)
fprintf(stderr, "Subscribe failed, rc %s reason code %s\n",
MQTTAsync_strerror(response->code),
MQTTReasonCode_toString(response->reasonCode));
finished = 1;
}
void onSubscribeFailure(void* context, MQTTAsync_failureData* response)
{
if (!opts.quiet)
fprintf(stderr, "Subscribe failed, rc %s\n",
MQTTAsync_strerror(response->code));
finished = 1;
}
void onConnectFailure5(void* context, MQTTAsync_failureData5* response)
{
if (!opts.quiet)
fprintf(stderr, "Connect failed, rc %s reason code %s\n",
MQTTAsync_strerror(response->code),
MQTTReasonCode_toString(response->reasonCode));
finished = 1;
}
void onConnectFailure(void* context, MQTTAsync_failureData* response)
{
if (!opts.quiet)
fprintf(stderr, "Connect failed, rc %s\n", response ? MQTTAsync_strerror(response->code) : "none");
finished = 1;
}
void onConnect5(void* context, MQTTAsync_successData5* response)
{
MQTTAsync client = (MQTTAsync)context;
MQTTAsync_callOptions copts = MQTTAsync_callOptions_initializer;
int rc;
if (opts.verbose)
printf("Subscribing to topic %s with client %s at QoS %d\n", opts.topic, opts.clientid, opts.qos);
copts.onSuccess5 = onSubscribe5;
copts.onFailure5 = onSubscribeFailure5;
copts.context = client;
if ((rc = MQTTAsync_subscribe(client, opts.topic, opts.qos, &copts)) != MQTTASYNC_SUCCESS)
{
if (!opts.quiet)
fprintf(stderr, "Failed to start subscribe, return code %s\n", MQTTAsync_strerror(rc));
finished = 1;
}
}
void onConnect(void* context, MQTTAsync_successData* response)
{
MQTTAsync client = (MQTTAsync)context;
MQTTAsync_responseOptions ropts = MQTTAsync_responseOptions_initializer;
int rc;
if (opts.verbose)
printf("Subscribing to topic %s with client %s at QoS %d\n", opts.topic, opts.clientid, opts.qos);
ropts.onSuccess = onSubscribe;
ropts.onFailure = onSubscribeFailure;
ropts.context = client;
if ((rc = MQTTAsync_subscribe(client, opts.topic, opts.qos, &ropts)) != MQTTASYNC_SUCCESS)
{
if (!opts.quiet)
fprintf(stderr, "Failed to start subscribe, return code %s\n", MQTTAsync_strerror(rc));
finished = 1;
}
}
MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
void trace_callback(enum MQTTASYNC_TRACE_LEVELS level, char* message)
{
fprintf(stderr, "Trace : %d, %s\n", level, message);
}
int main(int argc, char** argv)
{
MQTTAsync client;
MQTTAsync_disconnectOptions disc_opts = MQTTAsync_disconnectOptions_initializer;
MQTTAsync_createOptions create_opts = MQTTAsync_createOptions_initializer;
MQTTAsync_willOptions will_opts = MQTTAsync_willOptions_initializer;
MQTTAsync_SSLOptions ssl_opts = MQTTAsync_SSLOptions_initializer;
int rc = 0;
char* url = NULL;
const char* version = NULL;
const char* program_name = "paho_c_sub";
MQTTAsync_nameValue* infos = MQTTAsync_getVersionInfo();
#if !defined(WIN32)
struct sigaction sa;
#endif
if (argc < 2)
usage(&opts, (pubsub_opts_nameValue*)infos, program_name);
if (getopts(argc, argv, &opts) != 0)
usage(&opts, (pubsub_opts_nameValue*)infos, program_name);
if (strchr(opts.topic, '#') || strchr(opts.topic, '+'))
opts.verbose = 1;
if (opts.connection)
url = opts.connection;
else
{
url = malloc(100);
sprintf(url, "%s:%s", opts.host, opts.port);
}
if (opts.verbose)
printf("URL is %s\n", url);
if (opts.tracelevel > 0)
{
MQTTAsync_setTraceCallback(trace_callback);
MQTTAsync_setTraceLevel(opts.tracelevel);
}
if (opts.MQTTVersion >= MQTTVERSION_5)
create_opts.MQTTVersion = MQTTVERSION_5;
rc = MQTTAsync_createWithOptions(&client, url, opts.clientid, MQTTCLIENT_PERSISTENCE_NONE,
NULL, &create_opts);
if (rc != MQTTASYNC_SUCCESS)
{
if (!opts.quiet)
fprintf(stderr, "Failed to create client, return code: %s\n", MQTTAsync_strerror(rc));
exit(EXIT_FAILURE);
}
rc = MQTTAsync_setCallbacks(client, client, NULL, messageArrived, NULL);
if (rc != MQTTASYNC_SUCCESS)
{
if (!opts.quiet)
fprintf(stderr, "Failed to set callbacks, return code: %s\n", MQTTAsync_strerror(rc));
exit(EXIT_FAILURE);
}
#if defined(WIN32)
signal(SIGINT, cfinish);
signal(SIGTERM, cfinish);
#else
memset(&sa, 0, sizeof(struct sigaction));
sa.sa_handler = cfinish;
sa.sa_flags = 0;
sigaction(SIGINT, &sa, NULL);
sigaction(SIGTERM, &sa, NULL);
#endif
if (opts.MQTTVersion == MQTTVERSION_5)
{
MQTTAsync_connectOptions conn_opts5 = MQTTAsync_connectOptions_initializer5;
conn_opts = conn_opts5;
conn_opts.onSuccess5 = onConnect5;
conn_opts.onFailure5 = onConnectFailure5;
conn_opts.cleanstart = 1;
}
else
{
conn_opts.onSuccess = onConnect;
conn_opts.onFailure = onConnectFailure;
conn_opts.cleansession = 0;//conn_opts.cleansession = 1;
}
conn_opts.keepAliveInterval = opts.keepalive;
conn_opts.username = opts.username;
conn_opts.password = opts.password;
conn_opts.MQTTVersion = opts.MQTTVersion;
conn_opts.context = client;
conn_opts.automaticReconnect = 1;
if (opts.will_topic) /* will options */
{
will_opts.message = opts.will_payload;
will_opts.topicName = opts.will_topic;
will_opts.qos = opts.will_qos;
will_opts.retained = opts.will_retain;
conn_opts.will = &will_opts;
}
if (opts.connection && (strncmp(opts.connection, "ssl://", 6) == 0 ||
strncmp(opts.connection, "wss://", 6) == 0))
{
if (opts.insecure)
ssl_opts.verify = 0;
ssl_opts.CApath = opts.capath;
ssl_opts.keyStore = opts.cert;
ssl_opts.trustStore = opts.cafile;
ssl_opts.privateKey = opts.key;
ssl_opts.privateKeyPassword = opts.keypass;
ssl_opts.enabledCipherSuites = opts.ciphers;
conn_opts.ssl = &ssl_opts;
}
if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS)
{
if (!opts.quiet)
fprintf(stderr, "Failed to start connect, return code %s\n", MQTTAsync_strerror(rc));
exit(EXIT_FAILURE);
}
while (1)
{
mysleep(1000);
if (finished)
{
MQTTAsync_disconnect(client, &disc_opts);
printf("reconnet\n");
finished = 0;
MQTTAsync_connect(client, &conn_opts);
}
}
/*
while (!subscribed)
mysleep(100);
if (finished)
goto exit;
while (!finished)
mysleep(100);
disc_opts.onSuccess = onDisconnect;
if ((rc = MQTTAsync_disconnect(client, &disc_opts)) != MQTTASYNC_SUCCESS)
{
if (!opts.quiet)
fprintf(stderr, "Failed to start disconnect, return code: %s\n", MQTTAsync_strerror(rc));
exit(EXIT_FAILURE);
}
while (!disconnected)
mysleep(100);
*/
exit:
MQTTAsync_destroy(&client);
return EXIT_SUCCESS;
}
