assistant-android/app/src/main/java/com/gh/download/DownloadTask.java

package com.gh.download;

import android.content.Context;
import android.os.Handler;
import android.os.Message;

import com.gh.common.constant.Constants;
import com.gh.common.util.FileUtils;
import com.gh.common.util.Utils;

import java.text.DecimalFormat;

public class DownloadTask implements DownloadListener {

    private DownloadEntity entry;
    private Handler handler;
    private Context context;
    private DownloadThread downloadThread;

    private double currPercent;
    private long totalSize;
    private long currSize;

    // 计算下载速度
    private long lastTime;
    private long intervalDownloadedSize;

    public DownloadTask(Handler handler, final DownloadEntity entry,
                        Context context) {

        this.entry = entry;
        this.handler = handler;

        this.context = context;
        DownloadEntity historyEntry = DownloadDao.getInstance(context).get(
                entry.getUrl());
        if (historyEntry != null && historyEntry.getSize() != 0) {
            // 历史下载任务，初始化数据
            this.totalSize = entry.getSize();
            this.currPercent = (int) (entry.getProgress() * 100L / totalSize);
            Utils.log(DownloadTask.class.getSimpleName(),
                    "DownloadTask==>" + "历史下载任务，初始化数据");
        } else {
            // 第一次下载
            this.currSize = 0;
            this.currPercent = 0;
        }

    }

    public void start() {
        // 从下载历史里获取过去下载的进度信息
        DownloadEntity downloadEntity = DownloadDao.getInstance(context).get(entry.getUrl());

        if (downloadEntity != null) {
            entry = downloadEntity;
            entry.setStatus(DownloadStatus.downloading);
            Utils.log(DownloadTask.class.getSimpleName(),
                    "start==>" + "load from history:" + entry.getUrl()
                            + "--" + entry.getProgress() + "," + entry.getSize());
            currSize = entry.getProgress();
            currPercent = entry.getPercent();
        } else {
            Utils.log(DownloadTask.class.getSimpleName(), "start==>" + "First log into history!");
        }

        downloadThread = new DownloadThread(context, this.entry, this);
        downloadThread.setPriority(Thread.MAX_PRIORITY);
        downloadThread.start();
    }

    @Override
    public synchronized void onProgressChanged(long length, int len) {
        currSize = length;
        double percent = 0;
        if (entry.getSize() != 0) {
            percent = currSize * 100.0 / entry.getSize();
            DecimalFormat df = new DecimalFormat("#.0");
            percent = Double.parseDouble(df.format(percent));
        }
        entry.setProgress(currSize);
        if (percent == 100.0d) {
            entry.setPercent(100);
        } else {
            entry.setPercent(percent);
        }

        if (percent > currPercent) {
            currPercent = percent;
            Message msg = handler.obtainMessage();
            handler.removeMessages(0);
            msg.what = 0;
            msg.obj = entry;
            handler.sendMessage(msg);
            DownloadDao.getInstance(context).newOrUpdate(entry);
        }

        // 计算下载速度
        if (System.currentTimeMillis() - lastTime > Constants.SPEED_CHECK_INTERVAL) {
            long speed = intervalDownloadedSize / (Constants.SPEED_CHECK_INTERVAL);
            if (speed < 0) {
                entry.setSpeed(0);
            } else {
                entry.setSpeed(speed);
            }
            lastTime = System.currentTimeMillis();
            intervalDownloadedSize = 0;
            DownloadDao.getInstance(context).newOrUpdate(entry);
        } else {
            intervalDownloadedSize += len;
        }

        Utils.log(DownloadTask.class.getSimpleName(),
                "onProgressChanged==>" + entry.getName() + "**"
                        + entry.getPercent() + "%**" + entry.getSpeed() + "k/s");
    }

    @Override
    public void onStatusChanged(DownloadStatus status) {
        onStatusChanged(status, null);
    }

    @Override
    public void onStatusChanged(DownloadStatus status, String error) {
        if (status == DownloadStatus.cancel
                || status == DownloadStatus.hijack
                || status == DownloadStatus.notfound) {
            entry.setProgress(0);
            entry.setPercent(0);
            if (status == DownloadStatus.hijack) {
                entry.setError(error);
            }
            FileUtils.deleteFile(entry.getPath());
            DownloadDao.getInstance(context).delete(entry.getUrl());
            Utils.log(DownloadTask.class.getSimpleName(),
                    "onStatusChanged==>" + entry.getUrl() + " is calcled!");
        }

        if (status == DownloadStatus.done) {
            entry.setSpeed(0);
            entry.setProgress(entry.getSize());
            entry.setPercent(100);
            entry.setEnd(System.currentTimeMillis());
        }

        if (status == DownloadStatus.pause) {
            entry.setSpeed(0);
        }

        /*********************** 处理网络异常 ***********************/
        if (status == DownloadStatus.timeout || status == DownloadStatus.neterror) {
            entry.setError(error);
            DownloadTask task = DataChanger.getInstance().getDownloadingTasks().remove(entry.getUrl());
            if (task != null) {
                task.pause();
            }
        }

        entry.setStatus(status);
        DownloadDao.getInstance(context).newOrUpdate(entry);
        Message msg = handler.obtainMessage();
        msg.what = 1;
        msg.obj = entry;
        handler.sendMessage(msg);
        Utils.log(DownloadTask.class.getSimpleName(), "onStatusChanged:" + status);
    }

    public void pause() {
        downloadThread.setStatus(DownloadStatus.pause);
    }

    public void cancel() {
        downloadThread.setStatus(DownloadStatus.cancel);
    }

    public DownloadEntity getEntry() {
        return entry;
    }
}