【发布时间】：2017-03-27 05:33:35
【问题描述】：
我刚刚开始学习在 Android Studio 中使用 MQTT 协议。使用 mosquitto 代理，我能够在 pub/sub 窗口之间交换消息。但是当我通过 android studio 向代理发送消息时，应用程序构建成功，但代理端没有显示任何内容，并且系统打印连接失败。相同的代码在 eclipse java 应用程序上运行良好，但在 android 上无法运行，尽管已添加所需的库和依赖项。
请帮忙，我在这个基本步骤中缺少什么，以便我可以继续学习。谢谢！
app-build.gradle
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
exclude group: 'com.android.support', module: 'support-annotations'
})
compile 'com.android.support:appcompat-v7:25.2.0'
compile 'com.android.support.constraint:constraint-layout:1.0.2'
testCompile 'junit:junit:4.12'
// have added following dependencies
provided 'com.google.android.things:androidthings:0.2-devpreview'
provided 'com.google.android.things:androidthings:0.1-devpreview'
compile 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.0.2'
}
project-build.gradle
repositories {
jcenter()
maven {
url "https://repo.eclipse.org/content/repositories/paho-snapshots/"
}
}
AndroidManifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.zoha.mqttandroidiot">
<!-- Permissions the Application Requires -->
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".HomeActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
<!-- Launch activity automatically on boot -->
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.IOT_LAUNCHER"/>
<category android:name="android.intent.category.DEFAULT"/>
</intent-filter>
</activity>
<service android:name="org.eclipse.paho.android.service.MqttService"/>
</application>
</manifest>
HomeActivity
public class HomeActivity extends AppCompatActivity{
MqttAndroidClient client;
// private static final MemoryPersistence persistence = new MemoryPersistence();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final MqttAndroidClient mqttAndroidClient = new MqttAndroidClient(this.getApplicationContext(), "tcp://localhost:1883", "androidSampleClient");
mqttAndroidClient.setCallback(new MqttCallback() {
@Override
public void connectionLost(Throwable cause) {
System.out.println("Connection was lost!");
}
@Override
public void messageArrived(String topic, MqttMessage message) throws Exception {
System.out.println("Message Arrived!: " + topic + ": " + new String(message.getPayload()));
}
@Override
public void deliveryComplete(IMqttDeliveryToken token) {
System.out.println("Delivery Complete!");
}
});
try {
mqttAndroidClient.connect(null, new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken) {
System.out.println("Connection Success!");
try {
System.out.println("Subscribing to /test");
mqttAndroidClient.subscribe("/test", 0);
System.out.println("Subscribed to /test");
System.out.println("Publishing message..");
mqttAndroidClient.publish("/test", new MqttMessage("Hello world testing..!".getBytes()));
} catch (MqttException ex) {
}
}
@Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
System.out.println("Connection Failure!");
}
});
} catch (MqttException ex) {
}
}
}
【问题讨论】：
-
另外，请确保修复
AndroidManifest.xml文件中的service标签。service..标签应该在你的activity标签之外。所以复制‹service..行并将其粘贴到</activity>行下方 -
将BROKER url更改为您的系统IP地址而不是您的手机IP。
标签： android android-studio mqtt iot mosquitto