Example of using the REST API to retrieve an attachment from a form

package com.example;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;

import org.apache.commons.io.IOUtils;
import org.apache.http.HttpEntity;
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;

public class GetAttachment {

    public static void main(String[] args) throws Exception {
        String token = args[0];

       // start HTTP GET to get the attachment
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpGet httpGet = new HttpGet(
               "http://localhost:8008/api/arsys/v1/entry/AttachTest/000000000000001/attach/Attachment");

       // add the token to the header
        httpGet.addHeader("Authorization", "AR-JWT " + token);

       // make the call and write to a file
       try (CloseableHttpResponse response = httpClient.execute(httpGet)) {
            HttpEntity entity = response.getEntity();
            InputStream input = entity.getContent();

            File tempFile = File.createTempFile("screenshot", ".png");
           try (BufferedOutputStream output = new BufferedOutputStream(new FileOutputStream(
                    tempFile))) {
                IOUtils.copy(input, output);
                System.out.println("Attachment written to: " + tempFile);
            }
        }
    }

}