Question

在Android应用中（minSdkVersion 16）我使用nv-websocket-client库：

public class MainActivity extends AppCompatActivity {

    private WebSocket mWs;
    private WebSocketFactory mWsFactory = new WebSocketFactory();
    private WebSocketListener mWsListener = new WebSocketAdapter() {
        @Override
        public void onConnected(WebSocket ws, Map<String, List<String>> headers) throws Exception {
            mReconnectDispatcher.cancelAll();
        }

        // connection on the background thread has failed (onDisconnected will not be called!)
        @Override
        public void onConnectError(WebSocket ws, WebSocketException ex) throws Exception {
            reconnect();
        }

        @Override
        public void onDisconnected(WebSocket ws,
                                   WebSocketFrame serverCloseFrame, WebSocketFrame clientCloseFrame,
                                   boolean closedByServer) throws Exception {
            reconnect();
        }

        @Override
        public void onTextMessage(WebSocket ws, String str) throws Exception {
            // here the WebSockets communication happens
        }
    };

    @Override
    public void onResume() {
        super.onResume();
        reconnect();
    }

    @Override
    public void onPause() {
        super.onPause();
        if (mWs != null) {
            mWs.disconnect();
        }
    }

和Firebase JobDispatcher（版本0.8.4）重新连接WebSocket：

private FirebaseJobDispatcher mReconnectDispatcher;

public class ReconnectService extends JobService {
    @Override
    public boolean onStartJob(JobParameters job) {
        try {
            mWs = mWsFactory.createSocket("ws://demos.kaazing.com/echo");
            mWs.addListener(mWsListener);
            mWs.connectAsynchronously(); // uses background thread
        } catch (Exception ex) {
            Log.w(TAG, "Can not create WebSocket connection", ex);
        }

        return true; // Answers the question: "Is there still work going on?"
    }

    @Override
    public boolean onStopJob(JobParameters job) {
        return false; // Answers the question: "Should this job be retried?"
    }
}

private void reconnect() {
    Job myJob = mReconnectDispatcher.newJobBuilder()
        .setService(ReconnectService.class)
        .setTag(ReconnectService.class.getSimpleName())
        .setRecurring(false)
        .setLifetime(Lifetime.UNTIL_NEXT_BOOT)
        .setTrigger(Trigger.executionWindow(0, 60))
        .setReplaceCurrent(true)
        .setConstraints(Constraint.ON_ANY_NETWORK)
        .build();

    mReconnectDispatcher.mustSchedule(myJob);
}

在AndroidManifest.xml中我有：

<service
    android:name=".MainActivity$ReconnectService"
    android:exported="false">
    <intent-filter>
        <action android:name="com.firebase.jobdispatcher.ACTION_EXECUTE"/>
    </intent-filter>
</service>

不幸的是，我在60秒后收到运行时错误：

16998-16998/de.slova E/AndroidRuntime: FATAL EXCEPTION: main
   Process: de.slova, PID: 16998
   java.lang.RuntimeException: Unable to instantiate service de.slova.MainActivity$ReconnectService: java.lang.InstantiationException: java.lang.Class<de.slova.MainActivity$ReconnectService> has no zero argument constructor
       at android.app.ActivityThread.handleCreateService(ActivityThread.java:3389)
       at android.app.ActivityThread.-wrap4(Unknown Source:0)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1683)
       at android.os.Handler.dispatchMessage(Handler.java:105)
       at android.os.Looper.loop(Looper.java:164)
       at android.app.ActivityThread.main(ActivityThread.java:6541)
       at java.lang.reflect.Method.invoke(Native Method)
       at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
    Caused by: java.lang.InstantiationException: java.lang.Class<de.slova.MainActivity$ReconnectService> has no zero argument constructor
       at java.lang.Class.newInstance(Native Method)
       at android.app.ActivityThread.handleCreateService(ActivityThread.java:3386)
       at android.app.ActivityThread.-wrap4(Unknown Source:0) 
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1683) 
       at android.os.Handler.dispatchMessage(Handler.java:105) 
       at android.os.Looper.loop(Looper.java:164) 
       at android.app.ActivityThread.main(ActivityThread.java:6541) 
       at java.lang.reflect.Method.invoke(Native Method) 
       at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) 
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767) 
1472-1487/? I/ActivityManager: Showing crash dialog for package de.slova u0

我尝试在我的类中添加默认构造函数，但错误仍然存在：

public class ReconnectService extends JobService {
    public ReconnectService() {
    }

请有人知道，这里有什么问题？

我还将问题提交为issue #189。

Answer 1

将ReconnectService放在自己的类中（不是MainActivity的内部类）。或者，尝试制作内部类static。

非静态内部类在Java中的工作方式是它们只能由外部类的实例实例化。这是允许内部类的实例访问外部类的成员的原因。因此，当Android尝试创建内部类的实例时，它不能这样做，因为它不知道它应该属于哪个外部类的实例。错误消息有点误导。

如何使用Firebase JobDispatcher进行nv-websocket-client的异步重连？

1 个答案: