增加取消订阅消息

vue2/src/views/mqtt/demo.vue

@@ -6,7 +6,7 @@
       </el-form-item>
       <el-form-item label="操作">
         <el-button @click="subscribe">订阅</el-button>
-        <el-button @click="unsubscribe">取消</el-button>
+        <el-button @click="unsubscribe">取消订阅</el-button>
         <el-button @click="publish({type: orders.继续航线任务})">通过原始type发送指令</el-button>
         <el-button @click="order({order: '继续航线任务'})">通过关键字发送指令</el-button>
       </el-form-item>
@@ -63,7 +63,10 @@ export default {
     },
     unsubscribe(){
       this.$store.dispatch('MMCMQTT/unsubscribe', {
-        topic: this.topic
+        topic: this.topic,
+        callback(){
+          console.log('取消订阅')
+        }
       })  
     },
     publish({ type }){