从Google联系人迁移到People API。为Java构建它的小贴士？

从Google联系人迁移到People API的小贴士：

People API是Google提供的一种云原生API，用于管理和访问用户的联系人信息。它提供了一种简单而强大的方式来迁移和管理联系人数据。
在Java中使用People API，首先需要设置Google Cloud项目并启用People API。然后，您需要创建一个OAuth 2.0客户端ID，以便您的应用程序可以通过OAuth 2.0进行身份验证和授权。
在您的Java项目中，您需要使用Google API客户端库来访问People API。您可以通过将以下依赖项添加到您的项目的pom.xml文件中来引入Google API客户端库：

<dependency>
  <groupId>com.google.api-client</groupId>
  <artifactId>google-api-client</artifactId>
  <version>1.31.0</version>
</dependency>
<dependency>
  <groupId>com.google.oauth-client</groupId>
  <artifactId>google-oauth-client-jetty</artifactId>
  <version>1.31.0</version>
</dependency>

在您的代码中，您需要使用Google API客户端库来进行身份验证并调用People API。以下是一个简单的示例代码，用于从Google联系人中获取所有联系人的姓名和电子邮件：

import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeFlow;
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.googleapis.auth.oauth2.GoogleTokenResponse;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.services.people.v1.PeopleService;
import com.google.api.services.people.v1.PeopleServiceScopes;
import com.google.api.services.people.v1.model.ListConnectionsResponse;
import com.google.api.services.people.v1.model.Person;

import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.List;

public class PeopleApiExample {
    private static final String APPLICATION_NAME = "Your Application Name";
    private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
    private static final List<String> SCOPES = Arrays.asList(PeopleServiceScopes.CONTACTS_READONLY);

    public static void main(String[] args) throws Exception {
        HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();
        Credential credential = authorize(httpTransport);
        PeopleService peopleService = new PeopleService.Builder(httpTransport, JSON_FACTORY, credential)
                .setApplicationName(APPLICATION_NAME)
                .build();
        ListConnectionsResponse connectionsResponse = peopleService.people().connections().list("people/me")
                .setPersonFields("names,emailAddresses")
                .execute();
        List<Person> connections = connectionsResponse.getConnections();
        for (Person person : connections) {
            List<Person.Name> names = person.getNames();
            List<Person.EmailAddress> emailAddresses = person.getEmailAddresses();
            if (names != null && emailAddresses != null) {
                for (Person.Name name : names) {
                    System.out.println("Name: " + name.getDisplayName());
                }
                for (Person.EmailAddress emailAddress : emailAddresses) {
                    System.out.println("Email: " + emailAddress.getValue());
                }
            }
        }
    }

    private static Credential authorize(HttpTransport httpTransport) throws Exception {
        GoogleClientSecrets clientSecrets = GoogleClientSecrets.load(JSON_FACTORY,
                new InputStreamReader(PeopleApiExample.class.getResourceAsStream("/client_secrets.json")));
        GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(
                httpTransport, JSON_FACTORY, clientSecrets, SCOPES)
                .build();
        return new GoogleCredential.Builder()
                .setTransport(httpTransport)
                .setJsonFactory(JSON_FACTORY)
                .setClientSecrets(clientSecrets)
                .build()
                .setFromTokenResponse(flow.newTokenRequest("").setScopes(SCOPES).execute());
    }
}

在上述示例代码中，您需要将"Your Application Name"替换为您的应用程序的名称。您还需要创建一个名为"client_secrets.json"的JSON文件，其中包含您的OAuth 2.0客户端ID和客户端密钥。
通过运行上述代码，您将能够从Google联系人中获取所有联系人的姓名和电子邮件。