如何基于 Agora Android SDK 在应用中实现视频通话？

buildscript {     repositories {         ...         mavenCentral()     }     ...}   allprojects {     repositories {         ...         mavenCentral()     }}

...dependencies { ... // x.y.z，请填写具体的 SDK 版本号，如：3.5.0。 // 通过发版说明获取最新版本号。 implementation 'io.agora.rtc:full-sdk:x.y.z'}

<uses-permission android:name="android.permission.INTERNET" /><uses-permission android:name="android.permission.CAMERA" /><uses-permission android:name="android.permission.RECORD_AUDIO" /><uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" /><uses-permission android:name="android.permission.ACCESS_WIFI_STATE" /><uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /><uses-permission android:name="android.permission.BLUETOOTH" />

private static final int PERMISSION_REQ_ID = 22; private static final String[] REQUESTED_PERMISSIONS = {     Manifest.permission.RECORD_AUDIO,     Manifest.permission.CAMERA}; private boolean checkSelfPermission(String permission, int requestCode) {    if (ContextCompat.checkSelfPermission(this, permission) !=            PackageManager.PERMISSION_GRANTED) {        ActivityCompat.requestPermissions(this, REQUESTED_PERMISSIONS, requestCode);        return false;    }    return true;}

engine = RtcEngine.create(context.getApplicationContext(), getString(R.string.agora_app_id), iRtcEngineEventHandler);...private final IRtcEngineEventHandler iRtcEngineEventHandler = new IRtcEngineEventHandler(){    /**Reports a warning during SDK runtime.     * Warning code: https://docs.agora.io/en/Voice/API%20Reference/java/classio_1_1agora_1_1rtc_1_1_i_rtc_engine_event_handler_1_1_warn_code.html*/    @Override    public void onWarning(int warn)    {        Log.w(TAG, String.format("onWarning code %d message %s", warn, RtcEngine.getErrorDescription(warn)));    }     /**Reports an error during SDK runtime.     * Error code: https://docs.agora.io/en/Voice/API%20Reference/java/classio_1_1agora_1_1rtc_1_1_i_rtc_engine_event_handler_1_1_error_code.html*/    @Override    public void onError(int err)    {        Log.e(TAG, String.format("onError code %d message %s", err, RtcEngine.getErrorDescription(err)));        showAlert(String.format("onError code %d message %s", err, RtcEngine.getErrorDescription(err)));    }     /**Occurs when a user leaves the channel.     * @param stats With this callback, the application retrieves the channel information,     *              such as the call duration and statistics.*/    @Override    public void onLeaveChannel(RtcStats stats)    {        super.onLeaveChannel(stats);        Log.i(TAG, String.format("local user %d leaveChannel!", myUid));        showLongToast(String.format("local user %d leaveChannel!", myUid));    }     /**Occurs when the local user joins a specified channel.     * The channel name assignment is based on channelName specified in the joinChannel method.     * If the uid is not specified when joinChannel is called, the server automatically assigns a uid.     * @param channel Channel name     * @param uid User ID     * @param elapsed Time elapsed (ms) from the user calling joinChannel until this callback is triggered*/    @Override    public void onJoinChannelSuccess(String channel, int uid, int elapsed)    {        Log.i(TAG, String.format("onJoinChannelSuccess channel %s uid %d", channel, uid));        showLongToast(String.format("onJoinChannelSuccess channel %s uid %d", channel, uid));        myUid = uid;        joined = true;        handler.post(new Runnable()        {            @Override            public void run()            {                join.setEnabled(true);                join.setText(getString(R.string.leave));            }        });    }     @Override    public void onRemoteAudioStats(io.agora.rtc.IRtcEngineEventHandler.RemoteAudioStats remoteAudioStats) {        statisticsInfo.setRemoteAudioStats(remoteAudioStats);        updateRemoteStats();    }     @Override    public void onLocalAudioStats(io.agora.rtc.IRtcEngineEventHandler.LocalAudioStats localAudioStats) {        statisticsInfo.setLocalAudioStats(localAudioStats);        updateLocalStats();    }     @Override    public void onRemoteVideoStats(io.agora.rtc.IRtcEngineEventHandler.RemoteVideoStats remoteVideoStats) {        statisticsInfo.setRemoteVideoStats(remoteVideoStats);        updateRemoteStats();    }     @Override    public void onLocalVideoStats(io.agora.rtc.IRtcEngineEventHandler.LocalVideoStats localVideoStats) {        statisticsInfo.setLocalVideoStats(localVideoStats);        updateLocalStats();    }     @Override    public void onRtcStats(io.agora.rtc.IRtcEngineEventHandler.RtcStats rtcStats) {        statisticsInfo.setRtcStats(rtcStats);    }};

// Create render view by RtcEngineSurfaceView surfaceView = RtcEngine.CreateRendererView(context);if(fl_local.getChildCount() > 0){    fl_local.removeAllViews();}// Add to the local containerfl_local.addView(surfaceView, new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));// Setup local video to render your local camera previewengine.setupLocalVideo(new VideoCanvas(surfaceView, RENDER_MODE_HIDDEN, 0));// Enable video moduleengine.enableVideo();

ChannelMediaOptions option = new ChannelMediaOptions();option.autoSubscribeAudio = true;option.autoSubscribeVideo = true;int res = engine.joinChannel(accessToken, channelId, "Extra Optional Data", 0, option);if (res != 0){    // Usually happens with invalid parameters    // Error code description can be found at:    // en: https://docs.agora.io/en/Voice/API%20Reference/java/classio_1_1agora_1_1rtc_1_1_i_rtc_engine_event_handler_1_1_error_code.html    // cn: https://docs.agora.io/cn/Voice/API%20Reference/java/classio_1_1agora_1_1rtc_1_1_i_rtc_engine_event_handler_1_1_error_code.html    showAlert(RtcEngine.getErrorDescription(Math.abs(res)));    return;}

private final IRtcEngineEventHandler iRtcEngineEventHandler = new IRtcEngineEventHandler(){    ...    /**Occurs when a remote user (Communication)/host (Live Broadcast) joins the channel.     * @param uid ID of the user whose audio state changes.     * @param elapsed Time delay (ms) from the local user calling joinChannel/setClientRole     *                until this callback is triggered.*/    @Override    public void onUserJoined(int uid, int elapsed)    {        super.onUserJoined(uid, elapsed);        Log.i(TAG, "onUserJoined->" + uid);        showLongToast(String.format("user %d joined!", uid));        /**Check if the context is correct*/        Context context = getContext();        if (context == null) {            return;        }        if(remoteViews.containsKey(uid)){            return;        }        else{            handler.post(() ->            {                /**Display remote video stream*/                SurfaceView surfaceView = null;                // Create render view by RtcEngine                surfaceView = RtcEngine.CreateRendererView(context);                surfaceView.setZOrderMediaOverlay(true);                ViewGroup view = getAvailableView();                remoteViews.put(uid, view);                // Add to the remote container                view.addView(surfaceView, new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));                // Setup remote video to render                engine.setupRemoteVideo(new VideoCanvas(surfaceView, RENDER_MODE_HIDDEN, uid));            });        }    }     /**Occurs when a remote user (Communication)/host (Live Broadcast) leaves the channel.     * @param uid ID of the user whose audio state changes.     * @param reason Reason why the user goes offline:     *   USER_OFFLINE_QUIT(0): The user left the current channel.     *   USER_OFFLINE_DROPPED(1): The SDK timed out and the user dropped offline because no data     *              packet was received within a certain period of time. If a user quits the     *               call and the message is not passed to the SDK (due to an unreliable channel),     *               the SDK assumes the user dropped offline.     *   USER_OFFLINE_BECOME_AUDIENCE(2): (Live broadcast only.) The client role switched from     *               the host to the audience.*/    @Override    public void onUserOffline(int uid, int reason)    {        Log.i(TAG, String.format("user %d offline! reason:%d", uid, reason));        showLongToast(String.format("user %d offline! reason:%d", uid, reason));        handler.post(new Runnable() {            @Override            public void run() {                /**Clear render view                 Note: The video will stay at its last frame, to completely remove it you will need to                 remove the SurfaceView from its parent*/                engine.setupRemoteVideo(new VideoCanvas(null, RENDER_MODE_HIDDEN, uid));                remoteViews.get(uid).removeAllViews();                remoteViews.remove(uid);            }        });    }    ...};