apk下载服务：

package com.xxx.update;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import com.xxx.base.SczwApplication;
import com.xxx.sczwdemo.R;
import com.xxx.update.UpdateNotifiActivity.ICallbackResult;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.Binder;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.util.Log;
import android.widget.RemoteViews;

/**
 * @Date 2016-5-31 上午11:32:59
 * @Author Arvin
 * @Description 后台下载新版apk服务
 */ 
public class DownloadService extends Service {
    private static final String TAG = "DownloadService";
    private Context mContext = this;
    private static final int NOTIFY_ID = 0;
    private int progress;
    private NotificationManager mNotificationManager;
    private boolean canceled;
    // 返回的安装包url
        //http://softfile.3g.qq.com:8080/msoft/179/24659/43549/qq_hd_mini_1.4.apk
    private String apkUrl = "应用服务器地址";
    /* 下载包安装路径 */
    private static final String savePath = "/sdcard/updateApkDemo/";

    private static final String saveFileName = savePath + "3GQQ_AppUpdate.apk";
    private ICallbackResult callback;
    private DownloadBinder binder;
    private SczwApplication application;
    private boolean serviceIsDestroy = false;
    private Thread downLoadThread;
    private Notification mNotification;
    private int lastRate = 0;
    
    private static final int MSG_OVER_CANCEL = 0;//下载完毕取消
    private static final int MSG_UPDATE_PROGRESS = 1;//更新下载进度
    private static final int MSG_MANUAL_CANCEL = 2;//手动取消
    
    private Handler mHandler = new Handler() {

        @Override
        public void handleMessage(Message msg) {
            // TODO Auto-generated method stub
            super.handleMessage(msg);
            switch (msg.what) {
            case MSG_OVER_CANCEL:
                application.setDownload(false);
                // 下载完毕
                // 取消通知
                mNotificationManager.cancel(NOTIFY_ID);
                installApk();
                break;
            case MSG_MANUAL_CANCEL:
                application.setDownload(false);
                // 这里是用户界面手动取消，所以会经过activity的onDestroy();方法
                // 取消通知
                mNotificationManager.cancel(NOTIFY_ID);
                break;
            case MSG_UPDATE_PROGRESS:
                int rate = msg.arg1;
                application.setDownload(true);
                if (rate < 100) {
                    RemoteViews contentview = mNotification.contentView;
                    contentview.setTextViewText(R.id.tv_progress, rate + "%");
                    contentview.setProgressBar(R.id.progressbar, 100, rate, false);
                } else {
                    // 下载完毕后变换通知形式
                    mNotification.flags = Notification.FLAG_AUTO_CANCEL;
                    mNotification.contentView = null;
                    Intent intent = new Intent(mContext, UpdateNotifiActivity.class);
                    // 告知已完成
                    intent.putExtra("completed", "yes");
                    // 更新参数,注意flags要使用FLAG_UPDATE_CURRENT
                    PendingIntent contentIntent = PendingIntent.getActivity(mContext, 0, intent,
                            PendingIntent.FLAG_UPDATE_CURRENT);
                    mNotification.setLatestEventInfo(mContext, "下载完成", "文件已下载完毕", contentIntent);
                    //
                    serviceIsDestroy = true;
                    stopSelf();// 停掉服务自身
                }
                mNotificationManager.notify(NOTIFY_ID, mNotification);
                break;
            }
        }
    };

    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        Log.i(TAG,"是否执行了 onBind");
        return binder;
    }

    @Override
    public void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        Log.i(TAG,"downloadservice ondestroy");
        // 假如被销毁了，无论如何都默认取消了。
        application.setDownload(false);
    }

    @Override
    public boolean onUnbind(Intent intent) {
        // TODO Auto-generated method stub
        Log.i(TAG,"downloadservice onUnbind");
        return super.onUnbind(intent);
    }

    @Override
    public void onRebind(Intent intent) {
        // TODO Auto-generated method stub

        super.onRebind(intent);
        Log.i(TAG,"downloadservice onRebind");
    }

    @Override
    public void onCreate() {
        // TODO Auto-generated method stub
        super.onCreate();
        binder = new DownloadBinder();
        mNotificationManager = (NotificationManager) getSystemService(android.content.Context.NOTIFICATION_SERVICE);
//      setForeground(true);// 这个不确定是否有作用
        application = SczwApplication.getInstance();
    }

    public class DownloadBinder extends Binder {
        public void start() {
            if (downLoadThread == null || !downLoadThread.isAlive()) {
                progress = 0;
                setUpNotification();
                new Thread() {
                    public void run() {
                        // 下载
                        startDownload();
                    };
                }.start();
            }
        }

        public void cancel() {
            canceled = true;
        }

        public int getProgress() {
            return progress;
        }

        public boolean isCanceled() {
            return canceled;
        }

        public boolean serviceIsDestroy() {
            return serviceIsDestroy;
        }

        public void cancelNotification() {
            mHandler.sendEmptyMessage(MSG_MANUAL_CANCEL);
        }

        public void addCallback(ICallbackResult callback) {
            DownloadService.this.callback = callback;
        }
    }

    /**
     * @Description 启动新版apk下载任务
     * @param null
     * @return void
     * @throws
     */
    private void startDownload() {
        // TODO Auto-generated method stub
        canceled = false;
        downloadApk();
    }

    /**
     * @Description 创建通知
     * @param null
     * @return void
     * @throws
     */
    private void setUpNotification() {
        int icon = R.drawable.ic_launcher;
        CharSequence tickerText = "开始下载";
        long when = System.currentTimeMillis();
        mNotification = new Notification(icon, tickerText, when);
        // 放置在"正在运行"栏目中
        mNotification.flags = Notification.FLAG_ONGOING_EVENT;

        RemoteViews contentView = new RemoteViews(getPackageName(), R.layout.update_notif_ly);
        contentView.setTextViewText(R.id.name, "腾讯QQ.apk 正在下载...");
        // 指定个性化视图
        mNotification.contentView = contentView;

        Intent intent = new Intent(this, UpdateNotifiActivity.class);
        // 下面两句是 在按home后，点击通知栏，返回之前activity 状态;
        PendingIntent contentIntent = PendingIntent.getActivity(this, 0, intent,
                PendingIntent.FLAG_UPDATE_CURRENT);

        // 指定内容意图
        mNotification.contentIntent = contentIntent;
        mNotificationManager.notify(NOTIFY_ID, mNotification);
    }

    /**
     * @Description 下载新版apk
     * @param tags
     * @return return_type
     * @throws
     */
    private void downloadApk() {
        downLoadThread = new Thread(mdownApkRunnable);
        downLoadThread.start();
    }

    /**
     * @Description 安装新版apk
     * @param null
     * @return void
     * @throws
     */
    private void installApk() {
        File apkfile = new File(saveFileName);
        if (!apkfile.exists()) {
            return;
        }
        Intent i = new Intent(Intent.ACTION_VIEW);
        i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        i.setDataAndType(Uri.parse("file://" + apkfile.toString()), "application/vnd.android.package-archive");
        mContext.startActivity(i);
        callback.OnBackResult("finish");

    }

    /**
     * @Description 启动线程下载新版apk
     * @param String
     * @return null
     * @throws
     */
    private Runnable mdownApkRunnable = new Runnable() {
        @Override
        public void run() {
            try {
                URL url = new URL(apkUrl);

                HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                conn.connect();
                int length = conn.getContentLength();
                InputStream is = conn.getInputStream();

                File file = new File(savePath);
                if (!file.exists()) {
                    file.mkdirs();
                }
                String apkFile = saveFileName;
                File ApkFile = new File(apkFile);
                FileOutputStream fos = new FileOutputStream(ApkFile);

                int count = 0;
                byte buf[] = new byte[1024];

                do {
                    int numread = is.read(buf);
                    count += numread;
                    progress = (int) (((float) count / length) * 100);
                    // 更新进度
                    Message msg = mHandler.obtainMessage();
                    msg.what = MSG_UPDATE_PROGRESS;
                    msg.arg1 = progress;
                    if (progress >= lastRate + 1) {
                        mHandler.sendMessage(msg);
                        lastRate = progress;
                        if (callback != null)
                            callback.OnBackResult(progress);
                    }
                    if (numread <= 0) {
                        // 下载完成通知安装
                        mHandler.sendEmptyMessage(MSG_OVER_CANCEL);
                        // 下载完了，cancelled也要设置
                        canceled = true;
                        break;
                    }
                    fos.write(buf, 0, numread);
                } while (!canceled);// 点击取消就停止下载.

                fos.close();
                is.close();
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
    };

}

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