Android通知栏下载apk

import android.app.ActivityManager;
import android.app.DownloadManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.database.Cursor;
import android.net.Uri;
import android.os.Environment;
import android.support.v4.content.FileProvider;
import android.widget.Toast;

import com.example.simpledemo.R;
import com.example.simpledemo.base.BaseActivity;
import com.example.simpledemo.util.Utils;

import java.io.File;
import java.io.IOException;
import java.util.List;

import static android.content.Context.ACTIVITY_SERVICE;

public class DownloadUtils {
    /**
     * 下载器
     */
    private DownloadManager downloadManager;
    private Context mContext;
    /**
     * 下载的ID
     */
    private long downloadId;
    /**
     * apk保存路径
     */
    private String pathStr;

    public DownloadUtils(Context context, String url, String name) {
        this.mContext = context;
        downloadApk(url, name);
    }

    //下载apk
    private void downloadApk(String url, String name) {
        //设置下载的路径
        File file = new File(mContext.getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS), name);
        pathStr = file.getAbsolutePath();
        if (file.exists()) {
            installApk();
        } else {
            Toast.makeText(mContext, "开始下载，请在通知栏中查看进度。。。", Toast.LENGTH_SHORT).show();
            //创建下载任务
            DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
            //设置允许使用的网络类型，这里是移动网络和wifi都可以
            request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_MOBILE | DownloadManager.Request.NETWORK_WIFI);
            //在通知栏中显示，默认就是显示的(下载完也显示)
            request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
            //设置下载标题
            request.setTitle(mContext.getString(R.string.app_name));
            request.setDescription("我是描述");
            //显示在下载界面，即下载后的文件在系统下载管理里显示
            request.setVisibleInDownloadsUi(true);
            request.setDestinationUri(Uri.fromFile(file));
            //获取DownloadManager
            if (downloadManager == null) {
                downloadManager = (DownloadManager) mContext.getSystemService(Context.DOWNLOAD_SERVICE);
            }
            //将下载请求加入下载队列，加入下载队列后会给该任务返回一个long型的id，通过该id可以取消任务，重启任务、获取下载的文件等等
            if (downloadManager != null) {
                downloadId = downloadManager.enqueue(request);
            }
            //注册广播接收者，监听下载状态
            mContext.registerReceiver(receiver, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));
        }
    }

    /**
     * 广播监听下载的各个状态
     */
    private BroadcastReceiver receiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            checkStatus();
        }
    };

    /**
     * 检查下载状态
     */
    private void checkStatus() {
        DownloadManager.Query query = new DownloadManager.Query();
        //通过下载的id查找
        query.setFilterById(downloadId);
        Cursor cursor = downloadManager.query(query);
        if (cursor.moveToFirst()) {
            int status = cursor.getInt(cursor.getColumnIndex(DownloadManager.COLUMN_STATUS));
            switch (status) {
                case DownloadManager.STATUS_PAUSED:
                    //下载暂停
                    break;
                case DownloadManager.STATUS_PENDING:
                    //下载延迟
                    break;
                case DownloadManager.STATUS_RUNNING:
                    //正在下载
                    break;
                case DownloadManager.STATUS_SUCCESSFUL:
                    //下载完成安装APK
                    if (Utils.isAppBackground(mContext)) {
                        Toast.makeText(mContext, mContext.getString(R.string.app_name) + "下载完成，请到通知栏点击安装", Toast.LENGTH_SHORT).show();
                        setTopApp();
                    }
                    installApk();
                    cursor.close();
                    break;
                case DownloadManager.STATUS_FAILED:
                    //下载失败
                    Toast.makeText(mContext, "下载失败", Toast.LENGTH_SHORT).show();
                    cursor.close();
                    mContext.unregisterReceiver(receiver);
                    break;
                default:
                    break;
            }
        }
    }

    /**
     * 安装apk
     */
    private void installApk() {
        setPermission(pathStr);
        Intent intent = new Intent();
        intent.setAction(Intent.ACTION_VIEW);
        // 由于没有在Activity环境下启动Activity,设置下面的标签
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        //Android 7.0以上要使用FileProvider
        File file = new File(pathStr);
        //参数1 上下文, 参数2 Provider主机地址 和配置文件中保持一致   参数3  共享的文件
        Uri apkUri = FileProvider.getUriForFile(mContext, mContext.getPackageName() + ".fileprovider", file);
        //添加这一句表示对目标应用临时授权该Uri所代表的文件
        intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
        intent.setDataAndType(apkUri, "application/vnd.android.package-archive");
        mContext.startActivity(intent);
        ((BaseActivity) mContext).finish();
    }

    /**
     * 修改文件权限
     */
    private void setPermission(String absolutePath) {
        String command = "chmod 777 " + absolutePath;
        Runtime runtime = Runtime.getRuntime();
        try {
            runtime.exec(command);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 当本应用位于后台时，则将它切换到最前端
     */
    public void setTopApp() {
        //获取ActivityManager
        ActivityManager activityManager = (ActivityManager) mContext.getSystemService(ACTIVITY_SERVICE);

        //获得当前运行的task(任务)
        List<ActivityManager.RunningTaskInfo> taskInfoList = activityManager.getRunningTasks(100);
        for (ActivityManager.RunningTaskInfo taskInfo : taskInfoList) {
            //找到本应用的 task，并将它切换到前台
            if (taskInfo.topActivity.getPackageName().equals(mContext.getPackageName())) {
                activityManager.moveTaskToFront(taskInfo.id, 0);
                break;
            }
        }
    }
}

Utils:

/**
 * App 是否处于后台
 *
 * @param context
 * @return
 */
public static boolean isAppBackground(Context context) {
    ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
    List<ActivityManager.RunningAppProcessInfo> appProcesses = activityManager.getRunningAppProcesses();
    for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {
        if (appProcess.processName.equals(context.getPackageName())) {
            if (appProcess.importance != ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
                return true;
            } else {
                return false;
            }
        }
    }
    return false;
}

// 检测是否有写的权限
public static void verifyStoragePermissions(Activity activity) {
    try {
        //检测是否有写的权限
        int permission = ActivityCompat.checkSelfPermission(activity,
                "android.permission.WRITE_EXTERNAL_STORAGE");
        if (permission != PackageManager.PERMISSION_GRANTED) {
            // 没有写的权限，去申请写的权限，会弹出对话框
            ActivityCompat.requestPermissions(activity, PERMISSIONS_STORAGE, REQUEST_EXTERNAL_STORAGE);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

使用：

//通知栏下载apk
String url = "http://dldir1.qq.com/dlomg/weishi/weishi_guanwang.apk";
String fileName = "weishi_guanwang.apk";
new DownloadUtils(MainActivity.this, url, fileName);