前言

项目地址：https://github.com/teprinciple/UpdateAppDemo
现在的android应用app会隔一段时间发布一个新的版本，当你打开某个app，如果有最新的版本，会提醒你是否下载更新。本文利用android自带的下载管理器DownloadManager进行下载最新版本的apk，下载完成后自动跳转安装。效果如下：

第一步、检查版本并判断是否需要更新

通过获取当前app版本号与服务器上的版本号进行对比，如果本地的版本号低于服务器版本号，则弹出提示框：发现新版本，是否下载更新。

/**
 * Created by Teprinciple on 2016/11/15.
 */
public class UpdateAppUtil {

    /**
     * 获取当前apk的版本号 currentVersionCode
     * @param ctx
     * @return
     */
    public static int getAPPLocalVersion(Context ctx) {
        int currentVersionCode = 0;
        PackageManager manager = ctx.getPackageManager();
        try {
            PackageInfo info = manager.getPackageInfo(ctx.getPackageName(), 0);
            String appVersionName = info.versionName; // 版本名
            currentVersionCode = info.versionCode; // 版本号
        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
        }
        return currentVersionCode;
    }

    /**
     * 获取服务器上版本信息
     * @param context
     * @param callBack
     */
    public static void getAPPServerVersion(Context context, final VersionCallBack callBack){

        HttpUtil.getObject(Api.GETVERSION.mapClear().addBody(), VersionInfo.class, new HttpUtil.ObjectCallback() {
            @Override
            public void result(boolean b, @Nullable Object obj) {
                if (b){
                        callBack.callBack((VersionInfo) obj);
                }
            }
        });
    }

    /**
     * 判断版本号，更新APP
     * @param context
     */
    public static void updateApp(final Context context){
        getAPPServerVersion(context, new VersionCallBack() {
            @Override
            public void callBack(final VersionInfo info) {
                if (info != null && info.getVersionCode()!=null){

                    Log.i("this","版本信息：当前"+getAPPLocalVersion(context)+",服务器："+Integer.valueOf(info.getVersionCode()));

                    if (Integer.valueOf(info.getVersionCode()) > getAPPLocalVersion(context)){
                        ConfirmDialog dialog = new ConfirmDialog(context, new lht.wangtong.gowin120.doctor.views.feature.Callback() {
                            @Override
                            public void callback() {
                                DownloadAppUtils.downloadForAutoInstall(context, Api.HOST_IMG+info.getLoadPath(), "demo.apk", "更新demo");
                            }
                        });
                        dialog .setContent("发现新版本:"+info.getVersionNumber()+"\n是否下载更新?");
                        dialog.setCancelable(false);
                        dialog .show();
                    }
                }
            }
        });
    }

    public interface VersionCallBack{
        void callBack(VersionInfo info);
    }

}

第二步、下载最新版apk

通过Android自带的DownloadManager下载管理器，下载服务器上最新版的apk。下载完成后会发送下载完成的广播。

/**
 * Created by Teprinciple on 2016/11/15.
 */
public class DownloadAppUtils {
    private static final String TAG = DownloadAppUtils.class.getSimpleName();
    public static long downloadUpdateApkId = -1;//下载更新Apk 下载任务对应的Id
    public static String downloadUpdateApkFilePath;//下载更新Apk 文件路径

    /**
     * 通过浏览器下载APK包
     * @param context
     * @param url
     */
    public static void downloadForWebView(Context context, String url) {
        Uri uri = Uri.parse(url);
        Intent intent = new Intent(Intent.ACTION_VIEW, uri);
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setDataAndType(Uri.fromFile(new File(Environment
                        .getExternalStorageDirectory(), "tmp.apk")),
                "application/vnd.android.package-archive");
        context.startActivity(intent);
    }


    /**
     * 下载更新apk包
     * 权限:1,<uses-permission android:name="android.permission.DOWNLOAD_WITHOUT_NOTIFICATION" />
     * @param context
     * @param url
     */
    public static void downloadForAutoInstall(Context context, String url, String fileName, String title) {
        //LogUtil.e("App 下载 url="+url+",fileName="+fileName+",title="+title);
        if (TextUtils.isEmpty(url)) {
            return;
        }
        try {
            Uri uri = Uri.parse(url);
            DownloadManager downloadManager = (DownloadManager) context
                    .getSystemService(Context.DOWNLOAD_SERVICE);
            DownloadManager.Request request = new DownloadManager.Request(uri);
            //在通知栏中显示
            request.setVisibleInDownloadsUi(true);
            request.setTitle(title);
            String filePath = null;
            if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {//外部存储卡
                filePath = Environment.getExternalStorageDirectory().getAbsolutePath();

            } else {
                T.showShort(context, R.string.download_sdcard_error);
                return;
            }
            downloadUpdateApkFilePath = filePath + File.separator + fileName;
            // 若存在，则删除
            deleteFile(downloadUpdateApkFilePath);
            Uri fileUri = Uri.parse("file://" + downloadUpdateApkFilePath);
            request.setDestinationUri(fileUri);
            downloadUpdateApkId = downloadManager.enqueue(request);
        } catch (Exception e) {
            e.printStackTrace();
            downloadForWebView(context, url);
        }
    }


    private static boolean deleteFile(String fileStr) {
        File file = new File(fileStr);
        return file.delete();
    }
}

注意添加权限：

<uses-permission android:name="android.permission.DOWNLOAD_WITHOUT_NOTIFICATION" />

第三步、下载完成后跳转安装

通过广播接收者，接收到下载完成后发出的广播，跳转到系统的安装界面，进行安装。

/**
 * Created by Teprinciple on 2016/11/15.
 */
public class UpdateAppReceiver extends BroadcastReceiver {
    public UpdateAppReceiver() {
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        // 处理下载完成
        Cursor c=null;
        try {
            if (DownloadManager.ACTION_DOWNLOAD_COMPLETE.equals(intent.getAction())) {
                if (DownloadAppUtils.downloadUpdateApkId >= 0) {
                    long downloadId = DownloadAppUtils.downloadUpdateApkId;
                    DownloadManager.Query query = new DownloadManager.Query();
                    query.setFilterById(downloadId);
                    DownloadManager downloadManager = (DownloadManager) context
                            .getSystemService(Context.DOWNLOAD_SERVICE);
                    c = downloadManager.query(query);
                    if (c.moveToFirst()) {
                        int status = c.getInt(c
                                .getColumnIndex(DownloadManager.COLUMN_STATUS));
                        if (status == DownloadManager.STATUS_FAILED) {
                            downloadManager.remove(downloadId);

                        } else if (status == DownloadManager.STATUS_SUCCESSFUL) {
                            if (DownloadAppUtils.downloadUpdateApkFilePath != null) {
                                Intent i = new Intent(Intent.ACTION_VIEW);
                                i.setDataAndType(
                                        Uri.parse("file://"
                                                + DownloadAppUtils.downloadUpdateApkFilePath),
                                        "application/vnd.android.package-archive");
                                i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                                context.startActivity(i);
                            }
                        }
                    }
                }
            }/* else if (DownloadManager.ACTION_NOTIFICATION_CLICKED.equals(intent.getAction())) {//点击通知取消下载
                DownloadManager downloadManager = (DownloadManager) context
                        .getSystemService(Context.DOWNLOAD_SERVICE);
                long[] ids = intent.getLongArrayExtra(DownloadManager.EXTRA_NOTIFICATION_CLICK_DOWNLOAD_IDS);
                //点击通知栏取消下载
                downloadManager.remove(ids);
            }*/

        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            if (c != null) {
                c.close();
            }
        }
    }
}

注意需要在AndroidMainfest.xml中注册receiver：

<receiver android:name=".updateapp.UpdateAppReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.DOWNLOAD_COMPLETE" />
                <action android:name="android.intent.action.DOWNLOAD_NOTIFICATION_CLICKED"/>
            </intent-filter>
</receiver>

通过上面三步就可以快速实现APP的在线更新 。
项目地址：https://github.com/teprinciple/UpdateAppDemo