android 下载网络文件

工具类

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.os.Environment;
import android.util.Log;import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;public class FileDownloader extends AsyncTask<String, Integer, String> {private Context context;private ProgressDialog progressDialog;public FileDownloader(Context context) {this.context = context;}// 执行下载前的准备工作@Overrideprotected void onPreExecute() {super.onPreExecute();progressDialog = new ProgressDialog(context);progressDialog.setMessage("Downloading file...");progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);progressDialog.setCancelable(false);progressDialog.show();}// 后台下载文件@Overrideprotected String doInBackground(String... params) {String fileUrl = params[0];String fileName = params[1];String filePath = Environment.getExternalStorageDirectory().getPath() + "/" + fileName;try {URL url = new URL(fileUrl);HttpURLConnection connection = (HttpURLConnection) url.openConnection();connection.connect();int fileLength = connection.getContentLength();InputStream input = new BufferedInputStream(url.openStream());FileOutputStream output = new FileOutputStream(filePath);byte[] data = new byte[1024];long total = 0;int count;while ((count = input.read(data)) != -1) {total += count;publishProgress((int) (total * 100 / fileLength));output.write(data, 0, count);}output.flush();output.close();input.close();} catch (IOException e) {Log.e("FileDownloader", "Error: " + e.getMessage());}return filePath;}// 更新下载进度@Overrideprotected void onProgressUpdate(Integer... values) {super.onProgressUpdate(values);progressDialog.setProgress(values[0]);}// 下载完成后执行的操作@Overrideprotected void onPostExecute(String filePath) {super.onPostExecute(filePath);progressDialog.dismiss();// 在这里可以处理文件下载完成后的逻辑，比如打开文件等操作}
}

调用示例

String fileUrl = "http://www.example.com/file.pdf";
String fileName = "file.pdf";FileDownloader downloader = new FileDownloader(this);
downloader.execute(fileUrl, fileName);

注意事项

添加相应权限

<uses-permission android:name="android.permission.INTERNET"/>