(Java) Get Google Account Info from OAuth2 Access Token

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In the Google OAuth2 authorization flow, an application can know the email address of the Google account used to authorize access by requesting and processing user information from the Google UserInfo endpoint after obtaining an access token.

Chilkat Java Downloads Java Libs for Windows, MacOS, Linux, Alpine Linux, Solaris Java Libs for Android

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkHttp http = new CkHttp();
    boolean success;

    // Implements the following CURL command:

    // curl -H "Authorization: Bearer YOUR_ACCESS_TOKEN" https://www.googleapis.com/oauth2/v3/userinfo

    // Use the following online tool to generate HTTP code from a CURL command
    // Convert a cURL Command to HTTP Source Code

    // Adds the "Authorization: Bearer YOUR_ACCESS_TOKEN" header.
    http.put_AuthToken("YOUR_ACCESS_TOKEN");

    CkStringBuilder sbResponseBody = new CkStringBuilder();
    success = http.QuickGetSb("https://www.googleapis.com/oauth2/v3/userinfo",sbResponseBody);
    if (success == false) {
        System.out.println(http.lastErrorText());
        return;
        }

    CkJsonObject jResp = new CkJsonObject();
    jResp.LoadSb(sbResponseBody);
    jResp.put_EmitCompact(false);

    System.out.println("Response Body:");
    System.out.println(jResp.emit());

    int respStatusCode = http.get_LastStatus();
    System.out.println("Response Status Code = " + respStatusCode);
    if (respStatusCode >= 400) {
        System.out.println("Response Header:");
        System.out.println(http.lastHeader());
        System.out.println("Failed.");
        return;
        }

    // Sample JSON response:
    // (Sample code for parsing the JSON response is shown below)

    // {
    //   "sub": "112233445678901234567",
    //   "name": "John Doe",
    //   "given_name": "John",
    //   "family_name": "Doe",
    //   "profile": "https://plus.google.com/112233445678901234567",
    //   "picture": "https://lh3.googleusercontent.com/a-/AOh14GiU-EXAMPLE",
    //   "email": "johndoe@example.com",
    //   "email_verified": true,
    //   "locale": "en"
    // }

    // Sample code for parsing the JSON response...
    // Use the following online tool to generate parsing code from sample JSON:
    // Generate Parsing Code from JSON

    String v_sub = jResp.stringOf("sub");
    String name = jResp.stringOf("name");
    String given_name = jResp.stringOf("given_name");
    String family_name = jResp.stringOf("family_name");
    String profile = jResp.stringOf("profile");
    String picture = jResp.stringOf("picture");
    String email = jResp.stringOf("email");
    boolean email_verified = jResp.BoolOf("email_verified");
    String locale = jResp.stringOf("locale");
  }
}