要实现Android下载管理器多链接下载,可以使用多线程和断点续传的方式来处理。
首先,创建一个DownloadTask类来表示每个下载任务:
public class DownloadTask extends AsyncTask {
private Context context;
private String downloadUrl;
private String savePath;
private int downloadId;
public DownloadTask(Context context, String downloadUrl, String savePath, int downloadId) {
this.context = context;
this.downloadUrl = downloadUrl;
this.savePath = savePath;
this.downloadId = downloadId;
}
@Override
protected String doInBackground(String... params) {
try {
// 创建一个URL对象,用于连接下载地址
URL url = new URL(downloadUrl);
// 打开连接
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
// 设置请求方式为GET
connection.setRequestMethod("GET");
// 设置连接超时时间为10秒
connection.setConnectTimeout(10000);
// 设置读取超时时间为10秒
connection.setReadTimeout(10000);
// 设置下载位置
File file = new File(savePath);
if (!file.exists()) {
file.mkdirs();
}
File outputFile = new File(file, getFileName(downloadUrl));
// 设置请求头,指定从哪个位置开始下载
connection.setRequestProperty("Range", "bytes=" + outputFile.length() + "-");
// 获取下载输入流
InputStream inputStream = connection.getInputStream();
// 创建一个随机访问文件对象,用于实现断点续传
RandomAccessFile randomAccessFile = new RandomAccessFile(outputFile, "rw");
// 设置文件写入位置
randomAccessFile.seek(outputFile.length());
// 定义缓冲区
byte[] buffer = new byte[4096];
int length;
// 循环读取输入流并写入文件
while ((length = inputStream.read(buffer)) != -1) {
randomAccessFile.write(buffer, 0, length);
}
// 关闭流
inputStream.close();
randomAccessFile.close();
// 下载完成后发送广播通知下载完成
Intent intent = new Intent(DownloadManager.ACTION_DOWNLOAD_COMPLETE);
intent.putExtra(DownloadManager.EXTRA_DOWNLOAD_ID, downloadId);
context.sendBroadcast(intent);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
// 从下载地址中获取文件名
private String getFileName(String url) {
int index = url.lastIndexOf("/");
return url.substring(index + 1);
}
}
然后,在Activity或Fragment中使用DownloadManager来管理下载任务:
public class MainActivity extends AppCompatActivity {
private DownloadManager downloadManager;
private long downloadId1, downloadId2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
downloadManager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
// 下载链接1
String url1 = "http://example.com/file1.zip";
String savePath1 = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getPath();
DownloadManager.Request request1 = new DownloadManager.Request(Uri.parse(url1));
request1.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "file1.zip");
downloadId1 = downloadManager.enqueue(request1);
// 下载链接2
String url2 = "http://example.com/file2.zip";
String savePath2 = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getPath();
DownloadManager.Request request2 = new DownloadManager.Request(Uri.parse(url2));
request2.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "file2.zip");
downloadId2 = downloadManager.enqueue(request2);
// 注册下载完成的广播接收器
registerReceiver(downloadCompleteReceiver, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));
}
// 下载完成的广播接收器
private BroadcastReceiver downloadCompleteReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
long id = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);
if (id == downloadId1) {
// 下载链接1完成
// TODO: 处理下载完成的逻辑
} else if (id == downloadId2) {
// 下载链接2完成
// TODO: 处理下载完成的逻辑
}
}
};
@Override