Android: Download File code not working

2020-06-29 14:40发布

I'm trying to download a file from a URL. My code doesn't return an error but I can't see the file I'm supposed to download in my internal storage. Here's my code:

package com.example.downloadfile;

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

import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.widget.TextView;

public class DownloadFile extends Activity {

     private static String fileName = "al.jpg";

     @Override
     public void onCreate(Bundle savedInstanceState) 
     {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        TextView tv = new TextView(this);
        tv.setText("This is download file program... ");

        try {
            URL url = new URL("http://www.fullissue.com/wp-content/uploads/2010/12/Adam-Lambert.jpg");
            HttpURLConnection c = (HttpURLConnection) url.openConnection();
            c.setRequestMethod("GET");
            c.setDoOutput(true);
            c.connect();

            String PATH = Environment.getDataDirectory() + "/";

            tv.append("\nPath > " + PATH);

            Log.v("log_tag", "PATH: " + PATH);
            File file = new File(PATH);
            file.mkdirs();
            File outputFile = new File(file, fileName);
            FileOutputStream fos = new FileOutputStream(outputFile);

            InputStream is = c.getInputStream();

            byte[] buffer = new byte[1024];
            int len1 = 0;
            while ((len1 = is.read(buffer)) != -1) {
                fos.write(buffer, 0, len1);
            }
            fos.close();
            is.close();
        } catch (IOException e) {
            Log.d("log_tag", "Error: " + e);
        }
        Log.v("log_tag", "Check: ");

        tv.append("\nAnother append!");
        this.setContentView(tv);
    }

}

I'm new to java and android dev, any answers would be much appreciated, thanks!


Yo! I used the ff. code instead. This works for me. Thanks for all your help!

private static String fileName = "beautiful_galaxy - tarantula.jpg";
private static String fileURL = "http://apod.nasa.gov/apod/image/0903/tarantula2_hst_big.jpg";

    try {
        File root = Environment.getExternalStorageDirectory();
        URL u = new URL(fileURL);
        HttpURLConnection c = (HttpURLConnection) u.openConnection();
        c.setRequestMethod("GET");
        c.setDoOutput(true);
        c.connect();

        int lenghtOfFile = c.getContentLength();

        FileOutputStream f = new FileOutputStream(new File(root + "/download/", fileName));

        InputStream in = c.getInputStream();

        byte[] buffer = new byte[1024];
        int len1 = 0;
        long total = 0;

        while ((len1 = in.read(buffer)) > 0) {
            total += len1; //total = total + len1
            //publishProgress("" + (int)((total*100)/lenghtOfFile));
            f.write(buffer, 0, len1);
        }
        f.close();
    } catch (Exception e) {
        Log.d("Downloader", e.getMessage());
    }

6条回答
该账号已被封号
2楼-- · 2020-06-29 15:04

To download a file I use the following code:

public boolean DownloadFile(String url, File outputFile) 
{
try {
  URL u = new URL(url);
  URLConnection conn = u.openConnection();
  int contentLength = conn.getContentLength();

  DataInputStream stream = new DataInputStream(u.openStream());

  byte[] buffer = new byte[contentLength];
  stream.readFully(buffer);
  stream.close();

  DataOutputStream fos = new DataOutputStream(new FileOutputStream(outputFile));
  fos.write(buffer);
  fos.flush();
  fos.close();
  } 
catch(FileNotFoundException e) 
  {
  return false; 
  } 
catch (IOException e) 
  {
  return false; 
  }

return true;
}
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女痞
3楼-- · 2020-06-29 15:11

If you are downloading file to Sdcard then make sure that your sdcard is mounted, the code will download file to sdcard, if still getting problem let me know.

try {
            URL url = new URL(provide any URL);
            HttpURLConnection c = (HttpURLConnection) url.openConnection();
            c.setRequestMethod("GET");
            c.setDoOutput(true);
            c.connect();

            String PATH = Environment.getExternalStorageDirectory()
                    + "/download/";
            Log.v(LOG_TAG, "PATH: " + PATH);
            File file = new File(PATH);
            file.mkdirs();

            String fileName = "Test.mp3";


            File outputFile = new File(file, fileName);
            FileOutputStream fos = new FileOutputStream(outputFile);

            InputStream is = c.getInputStream();

            byte[] buffer = new byte[1024];
            int len1 = 0;
            while ((len1 = is.read(buffer)) != -1) {

                fos.write(buffer, 0, len1);

            }
            fos.close();
            is.close();

            // }
        } catch (IOException e) {
            Log.d(LOG_TAG, "Error: " + e);
            Toast.makeText(myApp, "error " + e.toString(), Toast.LENGTH_LONG)
                    .show();

        }


best of luck :)

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我欲成王,谁敢阻挡
4楼-- · 2020-06-29 15:12

Pretty sure (like @dmon said) that you can't write to the data directory in that fashion. You want to:

  1. Use Environment.getDownloadCacheDirectory () or Environment.getExternalStorageDirectory (). Take a look at the javadoc for http://developer.android.com/reference/android/os/Environment.html#getDataDirectory%28%29.
  2. Using URLConnection() is fine: this is standard java, and works just fine.
  3. What do the android logs say?
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戒情不戒烟
5楼-- · 2020-06-29 15:13

I saw this talk and the guy said you should use the Apache HTTP client and not the java one

Here is a code snippet take from the tutorial:

HttpClient httpclient = new DefaultHttpClient();
HttpGet httpget = new HttpGet("http://localhost/");
HttpResponse response = httpclient.execute(httpget);
HttpEntity entity = response.getEntity();
if (entity != null) {
    InputStream instream = entity.getContent();
    int l;
    byte[] tmp = new byte[2048];
    while ((l = instream.read(tmp)) != -1) {
    }
}
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欢心
6楼-- · 2020-06-29 15:21

Check the following permissions in Manifest file:

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
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We Are One
7楼-- · 2020-06-29 15:21

You will have a NetworkOnMainThreadException now. Look in the log cat. Place your internet code in an asynctask or thread.

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