从url下载文件，保存到手机存储

import android.os.AsyncTask;
import android.os.Environment;
import android.util.Log;

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class DownloadFileTask extends AsyncTask<String, Void, Void> {
    private static final String TAG = "DownloadFileTask";
    private String fileUrl;
    private String fileName;

    public DownloadFileTask(String fileUrl, String fileName) {
        this.fileUrl = fileUrl;
        this.fileName = fileName;
    }

    @Override
    protected Void doInBackground(String... params) {
        try {
            URL url = new URL(fileUrl);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.connect();

            if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) {
                Log.e(TAG, "Server returned HTTP " + connection.getResponseCode() + " " + connection.getResponseMessage());
                return null;
            }

            InputStream inputStream = connection.getInputStream();
            File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), fileName);
            FileOutputStream outputStream = new FileOutputStream(file);

            byte[] buffer = new byte[1024];
            int length;
            while ((length = inputStream.read(buffer)) > 0) {
                outputStream.write(buffer, 0, length);
            }

            outputStream.flush();
            outputStream.close();
            inputStream.close();

            Log.d(TAG, "File downloaded successfully: " + file.getAbsolutePath());
        } catch (Exception e) {
            Log.e(TAG, "Error downloading file", e);
        }
        return null;
    }
}

new DownloadFileTask("https://example.com/file.zip", "file.zip").execute();