对于STATUS_PAUSED状态的下载，可以通过DownloadManager.PAUSED_*静态常量来翻译出原因的整数码，进而判断出下载是由于等待网络连接还是等待WiFi连接还是准备重新下载三种原因而暂停。
对于STATUS_FAILED状态的下载，我们可以通过DownloadManager.ERROR_*来判断失败的原因，可能是错误码（失败原因）包括没有存储设备，
存储空间不足，重复的文件名，或者HTTP errors。
下面的代码是如何查询出当前所有的暂停的下载任务，提取出暂停的原因以及文件名称，下载标题以及当前进度的实现方法：
// Obtain the Download Manager Service.
String serviceString = Context.DOWNLOAD_SERVICE;
DownloadManager downloadManager;
downloadManager = (DownloadManager)getSystemService(serviceString);
// Create a query for paused downloads.
Query pausedDownloadQuery = new Query();
pausedDownloadQuery.setFilterByStatus(DownloadManager.STATUS_PAUSED);
// Query the Download Manager for paused downloads.
Cursor pausedDownloads = downloadManager.query(pausedDownloadQuery);
// Find the column indexes for the data we require.
int reasonIdx = pausedDownloads.getColumnIndex(DownloadManager.COLUMN_REASON);
int titleIdx = pausedDownloads.getColumnIndex(DownloadManager.COLUMN_TITLE);
int fileSizeIdx =
pausedDownloads.getColumnIndex(DownloadManager.COLUMN_TOTAL_SIZE_BYTES);
int bytesDLIdx =
pausedDownloads.getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR);
// Iterate over the result Cursor.
while (pausedDownloads.moveToNext()) {
// Extract the data we require from the Cursor.
String int fileSize = pausedDownloads.getInt(fileSizeIdx);
int bytesDL = pausedDownloads.getInt(bytesDLIdx);
// Translate the pause reason to friendly text.
int reason = pausedDownloads.getInt(reasonIdx);
String reasonString = "Unknown";
switch (reason) {
case DownloadManager.PAUSED_QUEUED_FOR_WIFI :
reasonString = "Waiting for WiFi"; break;
case DownloadManager.PAUSED_WAITING_FOR_NETWORK :
reasonString = "Waiting for connectivity"; break;
case DownloadManager.PAUSED_WAITING_TO_RETRY :
reasonString = "Waiting to retry"; break;
default : break;
}
// Construct a status summary
StringBuilder sb = new StringBuilder();
sb.append(title).append("n");
sb.append(reasonString).append("n");
sb.append("Downloaded ").append(bytesDL).append(" / " ).append(fileSize);
// Display the status
Log.d("DOWNLOAD", sb.toString());
}
// Close the result Cursor.
pausedDownloads.close();
