Android弹幕实现：基于B站弹幕开源系统（4）-重构

弹幕在视频播放的APP中比较常见，但是逻辑比较复杂，现在在附录1,2,3的基础上，我再次对弹幕进行抽象和重构，把弹幕从底向上抽象成不同的层，便于复用。

第一步，抽象数据层。
通常弹幕的来源是来源于后台的数据接口请求，在实时直播时候，是通过网络的轮询机制获取数据，那么，我把这部分代码抽出来设计成一个MGDanmakuHttpController，该类专注于数据的获取与分发：

package zhangphil.danmaku;

import android.os.Handler;
import android.os.Message;
import android.support.annotation.NonNull;
import android.util.Log;

import java.util.ArrayList;
import java.util.List;
import java.util.UUID;
import java.util.concurrent.Callable;

import io.reactivex.Observable;
import io.reactivex.android.schedulers.AndroidSchedulers;
import io.reactivex.observers.DisposableObserver;
import io.reactivex.schedulers.Schedulers;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

/**
 * Created by Phil on 2017/3/31.
 */

public class MGDanmakuHttpController {

    //private final String TAG = getClass().getName() + String.valueOf(UUID.randomUUID());

    private int msgId = 0;

    private DataMessageListener mDataMessageListener = null;
    private OkHttpClient mOkHttpClient;

    public MGDanmakuHttpController() {
        mOkHttpClient = new OkHttpClient();
    }

    private final int WHAT_START = 0xff0a;
    //private final int WHAT_STOP = WHAT_START + 1;

    private boolean promise = false;

    private int interval = 0;

    private Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);

            if (msg.what == WHAT_START) {
                handler.removeMessages(WHAT_START);

                try {
                    if (promise)
                        startRequestDanmaku();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    };


    public void startRequestDanmaku() throws Exception {
        promise = true;

        Observable mObservable = Observable.fromCallable(new Callable<List<DanmakuMsg>>() {
            @Override
            public List<DanmakuMsg> call() throws Exception {
                //同步方法返回观察者需要的数据结果
                //在这里处理线程化的操作
                return fetchData();
            }
        }).subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread());

        mObservable.subscribe(new DisposableObserver<List<DanmakuMsg>>() {

            @Override
            public void onNext(@NonNull List<DanmakuMsg> lists) {
                if (mDataMessageListener != null && promise) {
                    mDataMessageListener.onDataMessageListener(lists);
                }
            }

            @Override
            public void onComplete() {
                fireRequest();
            }

            @Override
            public void onError(Throwable e) {
                fireRequest();
            }
        });
    }

    public void stopRequestDanmaku() {
        promise = false;
    }

    /**
     * 设置轮询的间隔时间
     *
     * @param interval 单位毫秒 默认是0
     */
    public void setHttpRequestInterval(int interval) {
        this.interval = interval;
    }

    private void fireRequest() {
        //这里将触发重启数据请求，在这里可以调节重启数据请求的节奏。
        //比如可以设置一定的时延
        handler.sendEmptyMessageDelayed(WHAT_START, interval);
    }

    private List<DanmakuMsg> fetchData() {
        //同步方法返回观察者需要的数据结果
        //在这里处理线程化的操作
//        String url = "http://blog.csdn.net/zhangphil";
//        try {
//            Request request = new Request.Builder().url(url).build();
//            Response response = mOkHttpClient.newCall(request).execute();
//            if (response.isSuccessful()) {
//                byte[] bytes = response.body().bytes();
//                String data = new String(bytes, 0, bytes.length);


        try {
            Thread.sleep((int) (Math.random() * 500));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        int count = (int) (Math.random() * 10);

        //装配模拟数据
        List<DanmakuMsg> danmakuMsgs = new ArrayList<>();
        for (int i = 0; i < count; i++) {
            DanmakuMsg danmakuMsg = new DanmakuMsg();
            danmakuMsg.msg = String.valueOf(msgId++);
            danmakuMsgs.add(danmakuMsg);
        }

        return danmakuMsgs;
//            }
//        } catch (Exception e) {
//            e.printStackTrace();
//        }
//
//        return null;
    }


    public interface DataMessageListener {
        void onDataMessageListener(@NonNull List<DanmakuMsg> lists);
    }

    public void setDataMessageListener(DataMessageListener listener) {
        mDataMessageListener = listener;
    }
}

第二步，通过一个模型把弹幕的view和数据用胶水粘合在一起，我写了一个MGDanmaku：

package zhangphil.danmaku;

import android.graphics.Color;
import android.os.Handler;
import android.os.Message;
import android.support.annotation.NonNull;
import android.text.TextUtils;
import android.util.Log;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.UUID;
import java.util.concurrent.ConcurrentLinkedQueue;

import master.flame.danmaku.danmaku.model.BaseDanmaku;
import master.flame.danmaku.danmaku.model.DanmakuTimer;
import master.flame.danmaku.danmaku.model.IDisplayer;
import master.flame.danmaku.danmaku.model.android.DanmakuContext;
import master.flame.danmaku.ui.widget.DanmakuView;

/**
 * Created by Phil on 2017/4/1.
 */

public class MGDanmaku {
    private final String TAG = getClass().getName() + UUID.randomUUID();

    private MGDanmakuHttpController mMGDanmakuHttpController;
    private DanmakuView mDanmakuView;
    private AcFunDanmakuParser mParser;

    private DanmakuContext mDanmakuContext;

    private final int MAX_DANMAKU_LINES = 8; //弹幕在屏幕显示的最大行数

    private ConcurrentLinkedQueue<DanmakuMsg> mQueue = null; //所有的弹幕数据存取队列，在这里做线程的弹幕取和存
    private ArrayList<DanmakuMsg> danmakuLists = null;//每次请求最新的弹幕数据后缓存list

    private final int WHAT_GET_LIST_DATA = 0xffab01;
    private final int WHAT_DISPLAY_SINGLE_DANMAKU = 0xffab02;

    /**
     * 每次弹幕的各种颜色从这里面随机的选一个
     */
    private final int[] colors = {
            Color.RED,
            Color.YELLOW,
            Color.BLUE,
            Color.GREEN,
            Color.CYAN,
            Color.DKGRAY};

    //弹幕开关总控制
    // true正常显示和请求
    // false则取消
    private boolean isDanmukuEnable = false;

    public MGDanmaku(@NonNull DanmakuView view, @NonNull MGDanmakuHttpController controller) {
        this.mDanmakuView = view;
        this.mMGDanmakuHttpController = controller;

        initDanmaku();

        danmakuLists = new ArrayList<>();
        mQueue = new ConcurrentLinkedQueue<>();

        mMGDanmakuHttpController.setDataMessageListener(new MGDanmakuHttpController.DataMessageListener() {
            @Override
            public void onDataMessageListener(@NonNull List<DanmakuMsg> lists) {
                danmakuLists = (ArrayList<DanmakuMsg>) lists;
                //for (int i = 0; i < danmakuLists.size(); i++) {
                    //Log.d("获得数据", danmakuLists.get(i).msg);
                //}

                addListData();
            }
        });

        Log.d(getClass().getName(), TAG);
    }

    private Handler mDanmakuHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);

            switch (msg.what) {
                case WHAT_GET_LIST_DATA:
                    addListData();
                    break;

                case WHAT_DISPLAY_SINGLE_DANMAKU:
                    mDanmakuHandler.removeMessages(WHAT_DISPLAY_SINGLE_DANMAKU);
                    displayDanmaku();
                    break;
            }
        }
    };

    private void addListData() {
        if (danmakuLists != null && !danmakuLists.isEmpty()) {
            mDanmakuHandler.removeMessages(WHAT_GET_LIST_DATA);

            mQueue.addAll(danmakuLists);
            danmakuLists.clear();

            mDanmakuHandler.sendEmptyMessage(WHAT_DISPLAY_SINGLE_DANMAKU);
        }
    }


    private void initDanmaku() {
        // 设置最大显示行数
        HashMap<Integer, Integer> maxLinesPair = new HashMap<>();
        maxLinesPair.put(BaseDanmaku.TYPE_SCROLL_RL, MAX_DANMAKU_LINES); // 滚动弹幕最大显示5行

        // 设置是否禁止重叠
        HashMap<Integer, Boolean> overlappingEnablePair = new HashMap<>();
        overlappingEnablePair.put(BaseDanmaku.TYPE_SCROLL_RL, true);
        overlappingEnablePair.put(BaseDanmaku.TYPE_FIX_TOP, true);

        mDanmakuContext = DanmakuContext.create();

        //普通文本弹幕也描边设置样式
        //如果是图文混合编排编排，最后不要描边
        mDanmakuContext.setDanmakuStyle(IDisplayer.DANMAKU_STYLE_STROKEN, 10) //描边的厚度
                .setDuplicateMergingEnabled(false)
                .setScrollSpeedFactor(1.2f) //弹幕的速度。注意！此值越小，速度越快！值越大，速度越慢。// by phil
                .setScaleTextSize(1.2f)  //缩放的值
//        .setCacheStuffer(new BackgroundCacheStuffer())  // 绘制背景使用BackgroundCacheStuffer
                .setMaximumLines(maxLinesPair)
                .preventOverlapping(overlappingEnablePair);

        mParser = new AcFunDanmakuParser();
        mDanmakuView.prepare(mParser, mDanmakuContext);

        //mDanmakuView.showFPS(true);
        mDanmakuView.enableDanmakuDrawingCache(true);

        if (mDanmakuView != null) {
            mDanmakuView.setCallback(new master.flame.danmaku.controller.DrawHandler.Callback() {
                @Override
                public void updateTimer(DanmakuTimer timer) {
                }

                @Override
                public void drawingFinished() {

                }

                @Override
                public void danmakuShown(BaseDanmaku danmaku) {
                    Log.d("弹幕文本", "显示 text=" + danmaku.text);
                }

                @Override
                public void prepared() {
                    mDanmakuView.start();
                }
            });
        }
    }

    /**
     * 驱动弹幕显示机制重新运作起来
     */
    private void startDanmaku() {
        mDanmakuView.show();
        //mDanmakuView.start();

        mDanmakuHandler.sendEmptyMessage(WHAT_GET_LIST_DATA);
        mDanmakuHandler.sendEmptyMessage(WHAT_DISPLAY_SINGLE_DANMAKU);
    }

    private void stopDanmaku() {
        if (mDanmakuView != null) {
            mDanmakuView.hide();
            mDanmakuView.clearDanmakusOnScreen();
            mDanmakuView.clear();
        }

        mDanmakuHandler.removeMessages(WHAT_GET_LIST_DATA);
        mDanmakuHandler.removeMessages(WHAT_DISPLAY_SINGLE_DANMAKU);

        danmakuLists.clear();
        mQueue.clear();
    }

    public void setDanmakuRunning(boolean enable) {
        //如果是重复设置，则跳过
        if (isDanmukuEnable == enable) {
            return;
        }

        this.isDanmukuEnable = enable;

        //Log.d("isDanmukuEnable", String.valueOf(isDanmukuEnable));

        if (isDanmukuEnable) {
            startDanmaku();

            try {
                mMGDanmakuHttpController.startRequestDanmaku();
            } catch (Exception e) {
                e.printStackTrace();
            }
        } else {
            stopDanmaku();
            mMGDanmakuHttpController.stopRequestDanmaku();
        }
    }


    public boolean getDanmakuRunning() {
        return isDanmukuEnable;
    }

    public void sendMsg(@NonNull DanmakuMsg danmakuMsg) {
        displayDanmaku(danmakuMsg);
    }

    public void onResume() {
        if (mDanmakuView != null && mDanmakuView.isPrepared() && mDanmakuView.isPaused()) {
            mDanmakuView.resume();
        }
    }

    public void onPause() {
        if (mDanmakuView != null && mDanmakuView.isPrepared()) {
            mDanmakuView.pause();
        }
    }

    public void onDestroy() {
        if (mDanmakuView != null) {
            // dont forget release!
            mDanmakuView.release();
            mDanmakuView = null;
        }

        stopDanmaku();
    }

    private void displayDanmaku(@NonNull DanmakuMsg dm) {
        //如果当前的弹幕由于Android生命周期的原因进入暂停状态，那么不应该不停的消耗弹幕数据
        //要知道，在这里发出一个handler消息，那么将会消费（删掉）ConcurrentLinkedQueue头部的数据
        if (isDanmukuEnable) {
            if (!TextUtils.isEmpty(dm.msg)) {
                addDanmaku(dm.msg, dm.islive);
            }
        }
    }

    private void displayDanmaku() {
        //如果当前的弹幕由于Android生命周期的原因进入暂停状态，那么不应该不停的消耗弹幕数据
        //要知道，在这里发出一个handler消息，那么将会消费（删掉）ConcurrentLinkedQueue头部的数据
        boolean b = !mQueue.isEmpty() && getDanmakuRunning();
        if (b) {
            DanmakuMsg dm = mQueue.poll();
            if (!TextUtils.isEmpty(dm.msg)) {
                addDanmaku(dm.msg, dm.islive);//可以在此之后再加一行代码，驱动弹幕继续显示单个弹幕 mDanmakuHandler.sendEmptyMessageDelayed(WHAT_DISPLAY_SINGLE_DANMAKU, (long) (Math.random() * 400) + 100);
            }
        }
    }

    private void addDanmaku(CharSequence cs, boolean islive) {
        BaseDanmaku danmaku = mDanmakuContext.mDanmakuFactory.createDanmaku(BaseDanmaku.TYPE_SCROLL_RL);
        if (danmaku == null || mDanmakuView == null) {
            return;
        }

        danmaku.text = cs;
        danmaku.padding = 5;
        danmaku.priority = 0;  // 可能会被各种过滤器过滤并隐藏显示
        danmaku.isLive = islive;
        danmaku.setTime(mDanmakuView.getCurrentTime());
        danmaku.textSize = 20f * (mParser.getDisplayer().getDensity() - 0.6f); //文本弹幕字体大小
        danmaku.textColor = getRandomColor(); //文本的颜色
        danmaku.textShadowColor = getRandomColor(); //文本弹幕描边的颜色
        //danmaku.underlineColor = Color.DKGRAY; //文本弹幕下划线的颜色
        danmaku.borderColor = getRandomColor(); //边框的颜色

        mDanmakuView.addDanmaku(danmaku);
    }

    /**
     * 从一系列颜色中随机选择一种颜色
     *
     * @return
     */
    private int getRandomColor() {
        int i = ((int) (Math.random() * 10)) % colors.length;
        return colors[i];
    }
}

第三步，直接拿来在上层的activity用：

package zhangphil.danmaku;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.CompoundButton;

import master.flame.danmaku.ui.widget.DanmakuView;

public class MainActivity extends Activity {
    private MGDanmaku mMGDanmaku;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.d(getClass().getName(),"onCreate");

        DanmakuView mDanmakuView = (DanmakuView) findViewById(R.id.danmakuView);

        MGDanmakuHttpController mMGDanmakuHttpController = new MGDanmakuHttpController();
        mMGDanmakuHttpController.setHttpRequestInterval(0);
        mMGDanmaku = new MGDanmaku(mDanmakuView, mMGDanmakuHttpController);

        CheckBox checkBox = (CheckBox) findViewById(R.id.checkBox);
        checkBox.setChecked(mMGDanmaku.getDanmakuRunning());
        checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                mMGDanmaku.setDanmakuRunning(isChecked);
            }
        });

        Button sendText = (Button) findViewById(R.id.sendText);
        sendText.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                DanmakuMsg msg = new DanmakuMsg();
                msg.msg = "zhangphil: " + System.currentTimeMillis();

                mMGDanmaku.sendMsg(msg);
            }
        });
    }

    @Override
    protected void onResume() {
        super.onResume();
        mMGDanmaku.onResume();
    }

    @Override
    protected void onPause() {
        super.onPause();
        mMGDanmaku.onPause();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        mMGDanmaku.onDestroy();
    }
}

一个简单的弹幕数据消息封装包：

package zhangphil.danmaku;

/**
 * Created by Phil on 2017/3/31.
 */

import java.io.Serializable;

/**
 * 弹幕数据封装的类（bean）
 */
public class DanmakuMsg implements Serializable {
    public String id = "";
    public String msg = null;
    public boolean islive = true;
    public String point = "";
}

测试的MainActivity布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <CheckBox
        android:id="@+id/checkBox"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="弹幕开关" />

    <Button
        android:id="@+id/sendText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="发送文本弹幕" />

    <master.flame.danmaku.ui.widget.DanmakuView
        android:id="@+id/danmakuView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

注意！需要配置Activity在AndroidManifest.xml的属性configChanges和launchMode，以适应弹幕在横竖屏切换时的状态正确，配置如：

 <activity android:name=".MainActivity"
            android:configChanges="orientation|keyboardHidden|screenSize|fontScale"
            android:launchMode="singleTask">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

代码运行结果如图：

附录：
1，《Android弹幕实现：基于B站弹幕开源系统（1）》链接：http://blog.csdn.net/zhangphil/article/details/68067100 
2，《Android弹幕实现：基于B站弹幕开源系统（2）》链接：http://blog.csdn.net/zhangphil/article/details/68114226 
3，《Android弹幕实现：基于B站弹幕开源系统（3）-文本弹幕的完善和细节调整》链接：http://blog.csdn.net/zhangphil/article/details/68485505
4，《Java ConcurrentLinkedQueue队列线程安全操作》链接：http://blog.csdn.net/zhangphil/article/details/65936066