android 调用系统下载

android直接调用系统的下载方法进行文件下载，不废话，直接上代码：

首先，创建系统下载的工具类，

DownloadManagerUtil.java:

import android.app.DownloadManager;
import android.content.Context;
import android.net.Uri;
import android.os.Environment;

public class DownloadManagerUtil {
    private Context mContext;

    public DownloadManagerUtil(Context context) {
        mContext = context;
    }

    /**
     *
     * @param url 文件地址
     * @param title 通知栏标题
     * @param desc 通知栏描述
     * @return
     */
    public long download(String url, String title, String desc) {
        Uri uri = Uri.parse(url);
        DownloadManager.Request req = new DownloadManager.Request(uri);
        //设置WIFI下进行更新
        //req.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI);
        //下载中和下载完后都显示通知栏
        req.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
        //使用系统默认的下载路径 此处为应用内 /android/data/packages ,所以兼容7.0
        req.setDestinationInExternalFilesDir(mContext, Environment.DIRECTORY_DOWNLOADS, title);
        //通知栏标题
        req.setTitle(title);
        //通知栏描述信息
        req.setDescription(desc);
        //设置类型为.apk
        req.setMimeType("application/vnd.android.package-archive");
        //获取下载任务ID
        DownloadManager dm = (DownloadManager) mContext.getSystemService(Context.DOWNLOAD_SERVICE);
        return dm.enqueue(req);
    }


    /**
     * 下载前先移除前一个任务，防止重复下载
     *
     * @param downloadId
     */
    public void clearCurrentTask(long downloadId) {
        DownloadManager dm = (DownloadManager) mContext.getSystemService(Context.DOWNLOAD_SERVICE);
        try {
            dm.remove(downloadId);
        } catch (IllegalArgumentException ex) {
            ex.printStackTrace();
        }
    }
}

创建好工具类后，后面就是直接使用。代码如下：

首先，在调用下载的页面初始化工具类，然后调用下载，代码如下：

//创建全员变量
var downloadId = 0L
private var downloadManagerUtil: DownloadManagerUtil? = null


//在onCreate中初始化util
 downloadManagerUtil = DownloadManagerUtil(this)

//启用下载任务
 val url = "url"
 val title = "下载中"
 val desc = "下载完成后，点击安装"

 //先移除上一个下载任务，防止重复下载
 // 此处为单个文件下载，downloadId为下载任务id,可根据业务调整
  if (downloadId != 0L) {
      downloadManagerUtil!!.clearCurrentTask(downloadId)
  }

 downloadId = downloadManagerUtil!!.download(url, title, desc)

最后，需要建一个广播的接收类。用于接收下载完成的广播，代码如下：

DownloadReceiver.java:

import android.app.DownloadManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.util.Log;

import com.blankj.utilcode.util.AppUtils;
import com.cdd.sale.utils.UriToPathUtil;

public class DownloadReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {

        if (intent.getAction().equals(DownloadManager.ACTION_DOWNLOAD_COMPLETE)) {
            long id = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);
            installApk(context, id);
        } else if (intent.getAction().equals(DownloadManager.ACTION_NOTIFICATION_CLICKED)) {
            // DownloadManager manager = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);
            //获取所有下载任务Ids组
            //long[] ids = intent.getLongArrayExtra(DownloadManager.EXTRA_NOTIFICATION_CLICK_DOWNLOAD_IDS);
            //点击通知栏取消所有下载
            //manager.remove(ids);
            //Toast.makeText(context, "下载任务已取消", Toast.LENGTH_SHORT).show();
            //处理 如果还未完成下载，用户点击Notification ，跳转到下载中心
            Intent viewDownloadIntent = new Intent(DownloadManager.ACTION_VIEW_DOWNLOADS);
            viewDownloadIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            context.startActivity(viewDownloadIntent);
        }
    }

    private static void installApk(Context context, long downloadApkId) {
        DownloadManager dManager = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);
        Intent install = new Intent(Intent.ACTION_VIEW);
        Uri downloadFileUri = dManager.getUriForDownloadedFile(downloadApkId);
        if (downloadFileUri != null) {
           /* Log.d("DownloadManager", downloadFileUri.toString());
            install.setDataAndType(downloadFileUri, "application/vnd.android.package-archive");
            install.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            context.startActivity(install);*/
            String url = UriToPathUtil.getFilePathFromUri(context, downloadFileUri);
            AppUtils.installApp(url);
        } else {
            Log.e("DownloadManager", "download error");
        }
    }
}

注意在AndroidManifest中注册广播：

<receiver android:name="com.cdd.sale.util.DownloadReceiver">
            <intent-filter>
                <action android:name="android.intent.action.DOWNLOAD_COMPLETE" />
                <action android:name="android.intent.action.DOWNLOAD_NOTIFICATION_CLICKED" />
            </intent-filter>
</receiver>