视频断点续传下载

android {
  

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

}

依赖

implementation 'io.reactivex.rxjava2:rxjava:2.1.3'
implementation 'com.squareup.retrofit2:retrofit:2.3.0'
implementation 'com.squareup.retrofit2:converter-gson:2.3.0'
implementation 'com.squareup.retrofit2:adapter-rxjava2:2.3.0'
implementation 'io.reactivex.rxjava2:rxandroid:2.0.1'

implementation 'com.squareup.okhttp3:okhttp:3.2.0'

1.先建立  DownloadInfo类

public class DownloadInfo {
    public static final long TOTAL_ERROR = -1;//获取进度失败
    private String url;
    private long total;
    private long progress;
    private String fileName;

    public DownloadInfo(String url) {
        this.url = url;
    }

    public String getUrl() {
        return url;
    }

    public String getFileName() {
        return fileName;
    }

    public void setFileName(String fileName) {
        this.fileName = fileName;
    }

    public long getTotal() {
        return total;
    }

    public void setTotal(long total) {
        this.total = total;
    }

    public long getProgress() {
        return progress;
    }

    public void setProgress(long progress) {
        this.progress = progress;
    }
}

2.建立 DownloadManager类

import android.os.Environment;
import android.util.Log;

import com.example.lenovo.jiuyue.App;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.concurrent.atomic.AtomicReference;

import io.reactivex.Observable;
import io.reactivex.ObservableEmitter;
import io.reactivex.ObservableOnSubscribe;
import io.reactivex.android.schedulers.AndroidSchedulers;
import io.reactivex.schedulers.Schedulers;

import okhttp3.Call;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;


/**
 * Created by 陈丰尧 on 2017/2/2.
 */

public class DownloadManager {

    private static final AtomicReference<DownloadManager> INSTANCE = new AtomicReference<>();
    private HashMap<String, Call> downCalls;//用来存放各个下载的请求
    private OkHttpClient mClient;//OKHttpClient;

    //获得一个单例类
    public static DownloadManager getInstance() {
        for (; ; ) {
            DownloadManager current = INSTANCE.get();
            if (current != null) {
                return current;
            }
            current = new DownloadManager();
            if (INSTANCE.compareAndSet(null, current)) {
                return current;
            }
        }
    }

    private DownloadManager() {
        downCalls = new HashMap<>();
        mClient = new OkHttpClient.Builder().build();
    }

    /**
     * 开始下载
     *
     * @param url              下载请求的网址
     * @param downLoadObserver 用来回调的接口
     */
    public void download(String url, DownLoadObserver downLoadObserver) {
        Observable.just(url)
                .filter(s -> !downCalls.containsKey(s))//call的map已经有了,就证明正在下载,则这次不下载
                .flatMap(s -> Observable.just(createDownInfo(s)))
                .map(this::getRealFileName)//检测本地文件夹,生成新的文件名
                .flatMap(downloadInfo -> Observable.create(new DownloadSubscribe(downloadInfo)))//下载
                .observeOn(AndroidSchedulers.mainThread())//在主线程回调
                .subscribeOn(Schedulers.io())//在子线程执行
                .subscribe(downLoadObserver);//添加观察者

    }

    public void cancel(String url) {
        Call call = downCalls.get(url);
        if (call != null) {
            call.cancel();//取消
        }
        downCalls.remove(url);
    }

    /**
     * 创建DownInfo
     *
     * @param url 请求网址
     * @return DownInfo
     */
    public DownloadInfo createDownInfo(String url) {
        DownloadInfo downloadInfo = new DownloadInfo(url);
        long contentLength = getContentLength(url);//获得文件大小
        downloadInfo.setTotal(contentLength);
        String fileName = url.substring(url.lastIndexOf("/"));
        downloadInfo.setFileName(fileName);
        return downloadInfo;
    }

    private DownloadInfo getRealFileName(DownloadInfo downloadInfo) {
        String fileName = downloadInfo.getFileName();
        long downloadLength = 0, contentLength = downloadInfo.getTotal();
        File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/九悦/", fileName);
        Log.e("DownloadManager", "file:" + file);
        if (file.exists()) {
            //找到了文件,代表已经下载过,则获取其长度
            downloadLength = file.length();
        }
        //之前下载过,需要重新来一个文件
        int i = 1;
        while (downloadLength >= contentLength) {
            int dotIndex = fileName.lastIndexOf(".");
            String fileNameOther;
            if (dotIndex == -1) {
                fileNameOther = fileName + "(" + i + ")";
            } else {
                fileNameOther = fileName.substring(0, dotIndex)
                        + "(" + i + ")" + fileName.substring(dotIndex);
            }
            File newFile = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/九悦/", fileNameOther);
            Log.e("DownloadManager", "newFile:" + newFile);

            file = newFile;
            downloadLength = newFile.length();
            i++;
        }
        //设置改变过的文件名/大小
        downloadInfo.setProgress(downloadLength);
        downloadInfo.setFileName(file.getName());
        return downloadInfo;
    }

    private class DownloadSubscribe implements ObservableOnSubscribe<DownloadInfo> {
        private DownloadInfo downloadInfo;

        public DownloadSubscribe(DownloadInfo downloadInfo) {
            this.downloadInfo = downloadInfo;
        }

        @Override
        public void subscribe(ObservableEmitter<DownloadInfo> e) throws Exception {
            String url = downloadInfo.getUrl();
            long downloadLength = downloadInfo.getProgress();//已经下载好的长度
            long contentLength = downloadInfo.getTotal();//文件的总长度
            //初始进度信息
            e.onNext(downloadInfo);

            Request request = new Request.Builder()
                    //确定下载的范围,添加此头,则服务器就可以跳过已经下载好的部分
                    .addHeader("RANGE", "bytes=" + downloadLength + "-" + contentLength)
                    .url(url)
                    .build();
            Call call = mClient.newCall(request);
            downCalls.put(url, call);//把这个添加到call里,方便取消
            Response response = call.execute();

            File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/九悦/", downloadInfo.getFileName());
            InputStream is = null;
            FileOutputStream fileOutputStream = null;
            try {
                is = response.body().byteStream();
                fileOutputStream = new FileOutputStream(file, true);
                byte[] buffer = new byte[2048];//缓冲数组2kB
                int len;
                while ((len = is.read(buffer)) != -1) {
                    fileOutputStream.write(buffer, 0, len);
                    downloadLength += len;
                    downloadInfo.setProgress(downloadLength);
                    e.onNext(downloadInfo);
                }
                fileOutputStream.flush();
                downCalls.remove(url);
            } finally {
                is.close();
                fileOutputStream.close();
                //关闭IO流

            }
            e.onComplete();//完成
        }
    }

    /**
     * 获取下载长度
     *
     * @param downloadUrl
     * @return
     */
    private long getContentLength(String downloadUrl) {
        Request request = new Request.Builder()
                .url(downloadUrl)
                .build();
        try {
            Response response = mClient.newCall(request).execute();
            if (response != null && response.isSuccessful()) {
                long contentLength = response.body().contentLength();
                response.close();
                return contentLength == 0 ? DownloadInfo.TOTAL_ERROR : contentLength;
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return DownloadInfo.TOTAL_ERROR;
    }


}

3.DownLoadObserver

import io.reactivex.Observer;
import io.reactivex.disposables.Disposable;


/**
 * Created by 陈丰尧 on 2017/2/2.
 */

public  abstract class DownLoadObserver implements Observer<DownloadInfo> {
    protected Disposable d;//可以用于取消注册的监听者
    protected DownloadInfo downloadInfo;
    @Override
    public void onSubscribe(Disposable d) {
        this.d = d;
    }

    @Override
    public void onNext(DownloadInfo downloadInfo) {
        this.downloadInfo = downloadInfo;
    }

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


}

MainActivity

boolean biao=true;
    @OnClick(R.id.bt_download)
    public void onViewClicked() {
        if(biao){
            biao=false;
            xiazais.setImageResource(R.drawable.tasks_not_downloaded);
        DownloadManager.getInstance().download(url, new DownLoadObserver() {
            @Override
            public void onNext(DownloadInfo value) {
                super.onNext(value);

                double houss = (value.getTotal() * 1.00 / 1024 / 1000);
                double qainss = (value.getProgress() * 1.00 / 1024 / 1000);
                BigDecimal bg = new BigDecimal(houss);
                double jin1 = bg.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
                BigDecimal bg1 = new BigDecimal(qainss);
                double jin2 = bg1.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();

                hou.setText(jin1 + "M");
                qian.setText(jin2 + "M");

            }

            @Override
            public void onComplete() {
                if (downloadInfo != null) {
                    Toast.makeText(ShiPinActivity.this,
                            downloadInfo.getFileName() + "-DownloadComplete",
                            Toast.LENGTH_SHORT).show();


                    videoplayer.setVisibility(View.GONE);
                    videoView.setVisibility(View.VISIBLE);
                    String str = Environment.getExternalStorageDirectory() + "/九悦/"+downloadInfo.getFileName();

                    Uri uri = Uri.parse("file://" + str);
                    videoView.setMediaController(new MediaController(ShiPinActivity.this));
                    videoView.setVideoURI(uri);
                    videoView.start();
                    videoView.requestFocus();
                }
            }
        });

    }else {

            xiazais.setImageResource(R.drawable.tasks_paused);
            biao = true;

            DownloadManager.getInstance().cancel(url);



        }}

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