Android如何实现APP自动更新

import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.support.v7.app.NotificationCompat;

import com.fangku.commonlibrary.utils.StorageUtil;
import com.zhy.http.okhttp.OkHttpUtils;
import com.zhy.http.okhttp.callback.FileCallBack;

import java.io.File;

import okhttp3.Call;

/**
 * 自动下载更新apk服务
 * Create by: chenwei.li
 * Date: 2016-08-14
 * time: 09:50
 * Email: lichenwei.me@foxmail.com
 */
public class DownloadService extends Service {

 private String mDownloadUrl;//APK的下载路径
 private NotificationManager mNotificationManager;
 private Notification mNotification;


 @Override
 public void onCreate() {
 super.onCreate();
 mNotificationManager = (NotificationManager) getSystemService(Service.NOTIFICATION_SERVICE);

 }

 @Override
 public int onStartCommand(Intent intent, int flags, int startId) {
 if (intent == null) {
  notifyMsg("温馨提醒", "文件下载失败", 0);
  stopSelf();
 }
 mDownloadUrl = intent.getStringExtra("apkUrl");//获取下载APK的链接
 downloadFile(mDownloadUrl);//下载APK
 return super.onStartCommand(intent, flags, startId);
 }

 @Nullable
 @Override
 public IBinder onBind(Intent intent) {
 return null;
 }

 private void notifyMsg(String title, String content, int progress) {

 NotificationCompat.Builder builder = new NotificationCompat.Builder(this);//为了向下兼容，这里采用了v7包下的NotificationCompat来构造
 builder.setSmallIcon(R.mipmap.icon_login_logo).setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.icon_login_logo)).setContentTitle(title);
 if (progress > 0 && progress < 100) {
  //下载进行中
  builder.setProgress(100, progress, false);
 } else {
  builder.setProgress(0, 0, false);
 }
 builder.setAutoCancel(true);
 builder.setWhen(System.currentTimeMillis());
 builder.setContentText(content);
 if (progress >= 100) {
  //下载完成
  builder.setContentIntent(getInstallIntent());
 }
 mNotification = builder.build();
 mNotificationManager.notify(0, mNotification);


 }

 /**
 * 安装apk文件
 *
 * @return
 */
 private PendingIntent getInstallIntent() {
 File file = new File(StorageUtil.DOWNLOAD_DIR + "APP文件名");
 Intent intent = new Intent(Intent.ACTION_VIEW);
 intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
 intent.setDataAndType(Uri.parse("file://" + file.getAbsolutePath()), "application/vnd.android.package-archive");
 PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
 return pendingIntent;
 }


 /**
 * 下载apk文件
 *
 * @param url
 */
 private void downloadFile(String url) {

 OkHttpUtils.get().url(url).build().execute(new FileCallBack(StorageUtil.DOWNLOAD_DIR, "APP文件名") {
  @Override
  public void onError(Call call, Exception e, int id) {
  notifyMsg("温馨提醒", "文件下载失败", 0);
  stopSelf();
  }

  @Override
  public void onResponse(File response, int id) {
  //当文件下载完成后回调
  notifyMsg("温馨提醒", "文件下载已完成", 100);
  stopSelf();


  }

  @Override
  public void inProgress(float progress, long total, int id) {
  //progress*100为当前文件下载进度，total为文件大小
  if ((int) (progress * 100) % 10 == 0) {
   //避免频繁刷新View，这里设置每下载10%提醒更新一次进度
   notifyMsg("温馨提醒", "文件正在下载..", (int) (progress * 100));
  }
  }
 });


 }
}

Intent intent = new Intent(mContext, DownloadService.class);
intent.putExtra("apkUrl", "APK下载地址");
startService(intent);