[Android开发] 使用DownloadManager下载

主要使用DownloadManager.Request进行下载。

• 完整的项目：https://github.com/lijiancheng0614/android-NetworkConnect
• 参考：http://developer.android.com/reference/android/app/DownloadManager.html

可选

• 注册一个BroadcastReceiver来监听下载完成，并使用Callback来执行下载完成后的事件。

IntentFilter filter = new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE);context.registerReceiver(downloadReceiver, filter);

• 使用DownloadManager.Query查询是否下载成功。

• 设置Notification。

request.setNotificationVisibility(Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);

• 结合网络状况下载。

// Restrict the types of networks over which this download may proceed.request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI | DownloadManager.Request.NETWORK_MOBILE);// Set whether this download may proceed over a roaming connection.request.setAllowedOverRoaming(false);

代码

• DownloadHelper.java

package com.example.android.networkconnect;import android.app.DownloadManager;import android.app.DownloadManager.Request;import android.app.DownloadManager.Query;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;/** * Download file helper. */public class DownloadHelper {    private DownloadManager downloadManager;    private Request request;    private long downloadId = -1;    /**     * Broadcast when the download has successfully completed.     */    private BroadcastReceiver downloadReceiver = new BroadcastReceiver() {        @Override        public void onReceive(Context context, Intent intent) {            long completeDownloadId = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);            if (completeDownloadId == downloadId) {                // if download successful                if (getInt(downloadId, DownloadManager.COLUMN_STATUS) == DownloadManager.STATUS_SUCCESSFUL) {                    mDownloadDoneCallback.onDownloadDone();                }            }        }    };    private DownloadDoneCallback mDownloadDoneCallback;    public DownloadHelper(Context context, String uri, DownloadDoneCallback downloadDoneCallback) throws Exception {        downloadManager = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);        Uri downloadUri = Uri.parse(uri);        request = new Request(downloadUri);        String filename = downloadUri.getLastPathSegment();        request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, filename);        request.setTitle(filename);        request.setNotificationVisibility(Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);        mDownloadDoneCallback = downloadDoneCallback;        // Set filter to only when download is complete and register broadcast receiver        IntentFilter filter = new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE);        context.registerReceiver(downloadReceiver, filter);    }    /**     * Start downloading.     */    public void start() {        if (request == null) {            return;        }        //Enqueue a new download and same the referenceId        downloadId = downloadManager.enqueue(request);    }    /**     * Get int value of a column for the id.     *     * @param id         filter id.     * @param columnName column name.     * @return first value of the column for the id.     */    private int getInt(long id, String columnName) {        int result = -1;        Cursor cursor = null;        try {            Query query = new Query().setFilterById(id);            cursor = downloadManager.query(query);            if (cursor != null && cursor.moveToFirst()) {                result = cursor.getInt(cursor.getColumnIndex(columnName));            }        } finally {            if (cursor != null) {                cursor.close();            }        }        return result;    }    /**     * Callback when the download has successfully completed.     */    public interface DownloadDoneCallback {        public void onDownloadDone();    }}