Java: Download the file and save it in the location selected in the dialog [Use HttpClient]

Introduction

By the way, I decided to implement the following movement in Java local application in business.

1. Open a dialog to select the save destination
2. Save the file downloaded from the specified URL to the selected save destination It's a process that seems to be quite common, so I checked if there was an article that could be used as it is ~~ Copy and paste ~~ About each process such as Open dialog, ʻDownload file from URL and save` There was an article, but I couldn't find a complete one. Since it's a big deal, I wrote it in combination.

Below sample

• This time I am using apache.httpComponents for Http communication.

pom.xml

<!--abridgement-->
    <dependency>
      <groupId>org.apache.httpcomponents</groupId>
      <artifactId>httpclient</artifactId>
      <version>4.5.2</version>
    </dependency>
<!--abridgement-->

DownloadSample.java

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.Paths;
import javax.swing.JFileChooser;
import org.apache.http.HttpEntity;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

public class DownloadSample {
  //Download URL
  static String downloadUrl = "http://sample.com/hoge.txt";

  public static void main(String[] args) throws IOException {
    //Get the default file name from the URL.
    URL url = new URL(downloadUrl);
    String fileName = Paths.get(url.getPath()).getFileName().toString();

    //Display save dialog
    JFileChooser filechooser = new JFileChooser(fileName);
    //Specify the default file name
    filechooser.setSelectedFile(new File(fileName));
    //Show save dialog
    if (filechooser.showSaveDialog(null) != JFileChooser.APPROVE_OPTION) {
      //Exit when pressed other than "Save"
      return;
    }
    //Set save destination
    File saveFile = filechooser.getSelectedFile();
    try (
        //Set HttpClient
        final CloseableHttpClient client = HttpClients.createDefault();
        // Get
        final CloseableHttpResponse response = client.execute(new HttpGet(downloadUrl))) {
      //Check the status and save the file if communication is successful
      final int status = response.getStatusLine().getStatusCode();
      if (status >= 200 && status < 300) {
        final HttpEntity entity = response.getEntity();
        //Save file
        Files.write(Paths.get(saveFile.toString()),
            entity == null ? new byte[0] : EntityUtils.toByteArray(entity));
      } else {
        throw new ClientProtocolException("Unexpected response status: " + status);
      }
    }
  }
}

It's really just this sample, so it may not be necessary ... GitHub

References

Download and save the [Java] file (using Apache HttpComponents HttpClient 4.5.2) → Most of Http communication and file saving have been diverted from this article. Thank you! Display the "Save File" dialog Tips for using JFileChooser conveniently → I referred to this article for how to select the save dialog. Thank you! How to use java.net.URL and a little memo of NIO.2 → For the process of getting the file name from the URL, I referred to this article. Thank you!