Java

Download Binary File to In-Memory Bytes

See more Google Drive Examples

This example demonstrates how to download the binary content of a file from Google Drive directly into local memory. Chilkat2 Java

import com.chilkatsoft.chilkat2.AuthGoogle;
import com.chilkatsoft.chilkat2.Cache;
import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.FileAccess;
import com.chilkatsoft.chilkat2.Rest;
import com.chilkatsoft.chilkat2.StringBuilder;

public class ChilkatExample {

    public static void main(String[] args) {
        boolean success = false;

        success = true;

        // It requires the Chilkat API to have been previously unlocked.
        // See Global Unlock Sample for sample code.

        // This example uses a previously obtained access token having permission for the
        // Google Drive scope.

        AuthGoogle gAuth = new AuthGoogle();
        gAuth.setAccessToken("GOOGLE-DRIVE-ACCESS-TOKEN");

        Rest rest = new Rest();

        // Connect using TLS.
        // A single REST object, once connected, can be used for many Google Drive REST API calls.
        // The auto-reconnect indicates that if the already-established HTTPS connection is closed,
        // then it will be automatically re-established as needed.
        boolean bAutoReconnect = true;
        rest.connect("www.googleapis.com", 443, true, bAutoReconnect);

        // Provide the authentication credentials (i.e. the access token)
        rest.setAuthGoogle(gAuth);

        // ------------------------------------------------------------------------------
        // To download a file, we must know the file ID.
        // In a previous example (see Build Local Metadata Cache
        // we built a local cache to make it easy to lookup file IDs given a file path.
        // Let's say we want to download "testFolder/abc/123/penguins.jpg".
        // First we lookup the fileId in the cache.  With the fileId, we can download the file.
        Cache gdCache = new Cache();
        gdCache.setLevel(0);
        gdCache.addRoot("C:/ckCache/googleDrive");

        String fileId;
        try {
            fileId = gdCache.fetchText("testFolder/abc/123/penguins.jpg");
        } catch (ChilkatException e) {
            System.out.println("Filepath not found in cache.");
            return;
        }

        // We need to send a GET request like this:
        // GET https://www.googleapis.com/drive/v3/files/fileId?alt=media
        // The fileId is part of the path.
        StringBuilder sbPath = new StringBuilder();
        sbPath.append("/drive/v3/files/");
        sbPath.append(fileId);
        rest.addQueryParam("alt", "media");

        // To download to memory, we'll send the request in one call, then receive
        // the response header, and then the response body.
        // If the response header indicates failure or an unexpected response, then the
        // body is not the data we desire.

        // First send the HTTP request.
        try {
            rest.sendReqNoBody("GET", sbPath.getAsString());
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Get the response header.
        int statusCode = rest.readResponseHeader();
        if (statusCode != 200) {
            System.out.println("response status code = " + rest.getResponseStatusCode());
            System.out.println("response status text = " + rest.getResponseStatusText());
            System.out.println("response header: " + rest.getResponseHeader());

            // Read the response body (which should be error text or HTML)
            String errResponseBody;
            try {
                errResponseBody = rest.readRespBodyString();
            } catch (ChilkatException e) {
                errResponseBody = null;
            }
            if (errResponseBody != null) {
                System.out.println("response body: " + errResponseBody);
            }

            return;
        }

        // Read the response body, which should contain the file data.

ERROR: Invalid type for Chilkat2 Java: pbytes
ERROR: Method not in Chilkat2 Java: Rest.ReadRespBodyBinary
        jpgBytes = rest.ERROR();
        if (!rest.getLastMethodSuccess()) {
            System.out.println(rest.getLastErrorText());
            return;
        }

        // Save jpgBytes to a file so we can examine the file to verify that it worked.
        FileAccess fac = new FileAccess();
ERROR: Method not in Chilkat2 Java: FileAccess.WriteEntireFile
        fac.ERROR();

        System.out.println("File downloaded.");
    }
}