Download file from sharepoint site

package com.tgt.ding.sp.reader;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URI;
import java.net.URISyntaxException;

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.json.JSONObject;

public class SharePointDownload {

    private static final String SHAREPOINT_SITE = "https://basanonline.sharepoint.com/sites/ogrp-ds-basan";
    private static final String DOCUMENT_LIBRARY = "Documents";
    private static final String FILE_NAME = "Book.xlsx";
    private static final String CLIENT_ID = "your-client-id";
    private static final String CLIENT_SECRET = "your-client-secret";
    private static final String ACCESS_TOKEN = getAccessToken(CLIENT_ID, CLIENT_SECRET); // Implement access token retrieval logic

    public static void main(String[] args) throws URISyntaxException, IOException {
        String downloadUrl = buildDownloadUrl(SHAREPOINT_SITE, DOCUMENT_LIBRARY, FILE_NAME);
        downloadFile(downloadUrl, ACCESS_TOKEN);
    }

    private static String buildDownloadUrl(String siteUrl, String documentLibrary, String fileName) {
        return siteUrl + "/_api/web/GetFileByServerRelativePath(decodedurl='/sites/ogrp-ds-basan/Shared%20Documents/DataFolder/testCrawl/Book.xlsx')/$value";
    }

    private static void downloadFile(String downloadUrl, String accessToken) throws URISyntaxException, IOException {
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpGet request = new HttpGet(new URI(downloadUrl));
        request.addHeader("Authorization", "Bearer " + accessToken);

        try (CloseableHttpResponse response = httpClient.execute(request)) {
            int statusCode = response.getStatusLine().getStatusCode();
            if (statusCode == 200) {
                InputStream inputStream = response.getEntity().getContent();
                FileOutputStream outputStream = new FileOutputStream("Book.xlsx");
                byte[] buffer = new byte[1024];
                int bytesRead;
                while ((bytesRead = inputStream.read(buffer)) != -1) {
                    outputStream.write(buffer, 0, bytesRead);
                }
                outputStream.close();
                System.out.println("File downloaded successfully!");
            } else {
                System.out.println("Error downloading file: " + statusCode);
            }
        }
    }

    // Replace this with your access token retrieval logic using Azure AD
    private static String getAccessToken(String clientId, String clientSecret) {
        // Implement logic to get access token using Azure AD and OAuth 2.0 flow
        return "token";
    }
}

Get tenantid and resourceid

curl --request GET \

  --url https://basanonline.sharepoint.com/sites/ogrp-ds-basan/_vti_bin/client.svc \

  --header 'Authorization: Bearer bearer' \

  --header 'User-Agent: insomnia/8.6.1'

Look into www-authenticate header in response

Bearer r ealm="tenantid",client_id="clientidresource",trusted_issuers="tamper@*,D3776938-3DBA-481F-A652-4BEDFCAB7CD8@*,https://sts.windows.net/*/,https://login.microsoftonline.com/*/v2.0,tamperce00-000000000000@tenantid",authorization_uri="https://login.microsoftonline.com/common/oauth2/authorize"

Getting token using clientid, clientsecret and tenantid and clientidresource

curl --request POST \

  --url https://accounts.accesscontrol.windows.net/tenantid/tokens/OAuth/2 \

  --header 'Content-Type: application/x-www-form-urlencoded' \

  --data grant_type=client_credentials \

  --data client_id=clientid@tenantid\

  --data 'client_secret=ClientSECRET' \

  --data resource= clientidresource/basanonline.sharepoint.com@ tenantid

 https://sharepointcass.com/2021/04/01/sharepoint-online-rest-apis-part-iii-pages/