mqttexception（0）-java.net.sockettimeoutexception：无法连接到/192.168.1.xx（port 1883）30000ms之后的/10.0.2.xx（port xxxxx）

Question

我对Android开发的MQTT非常陌生。因此，我做了类似于本指南的事情。

我试图将我的Android应用程序从Android Studio Emulator连接到MQTT经纪人。该经纪人位于我的Windows10笔记本电脑（与Android客户端相同的机器）中。我发现的问题是我的Android客户端无法将自己连接到MQTT代理IP。我以多种方式尝试了它，但仍然无法正常工作。所以，我不确定我是否做对吗？

这是我的 build.gradle

dependencies {
    implementation 'androidx.appcompat:appcompat:1.4.1'
    implementation 'com.google.android.material:material:1.5.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.1.3'
    testImplementation 'junit:junit:4.13.2'
    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'

    implementation 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.1.0'
    implementation 'org.eclipse.paho:org.eclipse.paho.android.service:1.1.1'
    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
}

我的设置中的依赖项。

（应该在 build.gladle 文件中在我第一次尝试时，有一种编译应用程序的方式，它显示了“同步错误”。 。）

dependencyResolutionManagement {
    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
    repositories {
        google()
        mavenCentral()

        maven {
            url "https://repo.eclipse.org/content/repositories/paho-releases/"
        }
    }
}

androidmanifest.xml ，我包括了一些许可和 android Service 。

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.smartmousetrap">

    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.READ_PHONE_STATE" />

    <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/Theme.SmartMouseTrap">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <service android:name="org.eclipse.paho.android.service.MqttService"/>

    </application>

</manifest>

这是首先具有连接问题的所有 mainActivity.java

public class MainActivity extends AppCompatActivity {

    private Button buttonConnect;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        buttonConnect = findViewById(R.id.buttonConnect);
        buttonConnect.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String clientId = MqttClient.generateClientId();
                Toast.makeText(MainActivity.this, clientId, Toast.LENGTH_SHORT).show();
                MqttAndroidClient client = new MqttAndroidClient(MainActivity.this, "tcp://192.168.1.43:1883", clientId);

                try {
                    IMqttToken token = client.connect();
                    token.setActionCallback(new IMqttActionListener() {
                        @Override
                        public void onSuccess(IMqttToken asyncActionToken) {
                            Log.d("Debug", "onSuccess");
                            Toast.makeText(MainActivity.this, "onSuccess", Toast.LENGTH_SHORT).show();
                        }

                        @Override
                        public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
                            Log.d("Debug", "onFailure");
                            Toast.makeText(MainActivity.this, "onFailure", Toast.LENGTH_SHORT).show();
                            exception.printStackTrace();
                        }
                    });
                } catch (MqttException e) {
                    e.printStackTrace();
                }
            }
        });
    }
}

，我使用此变量引用该按钮。单击按钮时，应用程序将自身连接到MQTT代理。

buttonConnect = findViewById（r.id.buttonConnect）;

buttonConnect.setOnClickListener（new View.OnClickListener（）{...}）{...}）

========================================== =================================

'192.168.1.43'是我的笔记本电脑IP（Broker）

mqttandroidclient客户端=新的mqttandroidclient（mainActivity.this，“ tcp：//192.168.1.43：1883”，clientid）;

========================================================================================== =========================

它尝试了“ client.connect”后，它最终进入了此“ Failure”部分。

imqtttoken token = client.connect（）;

try {
    IMqttToken token = client.connect();
    token.setActionCallback(new IMqttActionListener() {
        @Override
        public void onSuccess(IMqttToken asyncActionToken) {
            Log.d("Debug", "onSuccess");
            Toast.makeText(MainActivity.this, "onSuccess", Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
            Log.d("Debug", "onFailure");
            Toast.makeText(MainActivity.this, "onFailure", Toast.LENGTH_SHORT).show();
            exception.printStackTrace();
        }
    });
} catch (MqttException e) {
    e.printStackTrace();
}

这是我遇到的 mqttexception 提示的错误。

请注意， 10.0.2.16 是我的Android IP（来自Android Studio Emulator），

D/HostConnection: createUnique: call
D/HostConnection: HostConnection::get() New Host Connection established 0x75161b0e2c50, tid 7084
D/HostConnection: HostComposition ext ANDROID_EMU_CHECKSUM_HELPER_v1 ANDROID_EMU_native_sync_v2 ANDROID_EMU_native_sync_v3 ANDROID_EMU_native_sync_v4 ANDROID_EMU_dma_v1 ANDROID_EMU_direct_mem ANDROID_EMU_host_composition_v1 ANDROID_EMU_host_composition_v2 ANDROID_EMU_vulkan ANDROID_EMU_deferred_vulkan_commands ANDROID_EMU_vulkan_null_optional_strings ANDROID_EMU_vulkan_create_resources_with_requirements ANDROID_EMU_YUV_Cache ANDROID_EMU_vulkan_ignored_handles ANDROID_EMU_has_shared_slots_host_memory_allocator ANDROID_EMU_vulkan_free_memory_sync ANDROID_EMU_vulkan_shader_float16_int8 ANDROID_EMU_vulkan_async_queue_submit ANDROID_EMU_vulkan_queue_submit_with_commands ANDROID_EMU_sync_buffer_data ANDROID_EMU_read_color_buffer_dma GL_OES_vertex_array_object GL_KHR_texture_compression_astc_ldr ANDROID_EMU_host_side_tracing ANDROID_EMU_gles_max_version_2 
W/OpenGLRenderer: Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without...
W/OpenGLRenderer: Failed to initialize 101010-2 format, error = EGL_SUCCESS
D/EGL_emulation: eglCreateContext: 0x75161b0e2650: maj 2 min 0 rcv 2
D/EGL_emulation: eglMakeCurrent: 0x75161b0e2650: ver 2 0 (tinfo 0x751835ee2080) (first time)
I/Gralloc4: mapper 4.x is not supported
D/HostConnection: createUnique: call
D/HostConnection: HostConnection::get() New Host Connection established 0x75161b0e2110, tid 7084
D/goldfish-address-space: allocate: Ask for block of size 0x100
D/goldfish-address-space: allocate: ioctl allocate returned offset 0x3efffe000 size 0x2000
W/Gralloc4: allocator 4.x is not supported
D/HostConnection: HostComposition ext ANDROID_EMU_CHECKSUM_HELPER_v1 ANDROID_EMU_native_sync_v2 ANDROID_EMU_native_sync_v3 ANDROID_EMU_native_sync_v4 ANDROID_EMU_dma_v1 ANDROID_EMU_direct_mem ANDROID_EMU_host_composition_v1 ANDROID_EMU_host_composition_v2 ANDROID_EMU_vulkan ANDROID_EMU_deferred_vulkan_commands ANDROID_EMU_vulkan_null_optional_strings ANDROID_EMU_vulkan_create_resources_with_requirements ANDROID_EMU_YUV_Cache ANDROID_EMU_vulkan_ignored_handles ANDROID_EMU_has_shared_slots_host_memory_allocator ANDROID_EMU_vulkan_free_memory_sync ANDROID_EMU_vulkan_shader_float16_int8 ANDROID_EMU_vulkan_async_queue_submit ANDROID_EMU_vulkan_queue_submit_with_commands ANDROID_EMU_sync_buffer_data ANDROID_EMU_read_color_buffer_dma GL_OES_vertex_array_object GL_KHR_texture_compression_astc_ldr ANDROID_EMU_host_side_tracing ANDROID_EMU_gles_max_version_2 
W/System: A resource failed to call close. 
D/EGL_emulation: app_time_stats: avg=409.15ms min=4.48ms max=3278.83ms count=9
D/CompatibilityChangeReporter: Compat change id reported: 147798919; UID 10166; state: ENABLED
D/AlarmPingSender: Unregister alarmreceiver to MqttServicepaho3870573646500
D/AlarmPingSender: Unregister alarmreceiver to MqttServicepaho3870573646500
D/Debug: onFailure
W/System.err: MqttException (0) - java.net.SocketTimeoutException: failed to connect to /192.168.1.43 (port 1883) from /10.0.2.16 (port 56170) after 30000ms
W/System.err:     at org.eclipse.paho.client.mqttv3.internal.ExceptionHelper.createMqttException(ExceptionHelper.java:38)
W/System.err:     at org.eclipse.paho.client.mqttv3.internal.ClientComms$ConnectBG.run(ClientComms.java:664)
W/System.err:     at java.lang.Thread.run(Thread.java:920)
W/System.err: Caused by: java.net.SocketTimeoutException: failed to connect to /192.168.1.43 (port 1883) from /10.0.2.16 (port 56170) after 30000ms
W/System.err:     at libcore.io.IoBridge.connectErrno(IoBridge.java:236)
W/System.err:     at libcore.io.IoBridge.connect(IoBridge.java:180)
W/System.err:     at java.net.PlainSocketImpl.socketConnect(PlainSocketImpl.java:142)
W/System.err:     at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:390)
W/System.err:     at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:230)
W/System.err:     at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:212)
W/System.err:     at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:436)
W/System.err:     at java.net.Socket.connect(Socket.java:621)
W/System.err:     at org.eclipse.paho.client.mqttv3.internal.TCPNetworkModule.start(TCPNetworkModule.java:70)
W/System.err:     at org.eclipse.paho.client.mqttv3.internal.ClientComms$ConnectBG.run(ClientComms.java:650)
W/System.err:   ... 1 more

如果我做错了什么或任何建议，请提供帮助。

Answer 1

以下内容类似于：

如何在 Android 模拟器中连接 localhost？

您可能需要访问经纪人：

10.0.2.2:1883