我正在尝试使用Google Drive Service Java API上传文件。我正在使用Quickstart.java示例来弄清楚我需要编写的代码。我收到编译器错误。请协助解决我的编译器错误。
Quickstart.java:107: error: cannot find symbol
.setPageSize(10)
^
symbol: method setPageSize(int)
location: class Drive.Files.List
Quickstart.java:110: error: cannot find symbol
List<File> files = result.getFiles();
^
symbol: method getFiles()
location: variable result of type FileList
Quickstart.java:116: error: cannot find symbol
System.out.printf("%s (%s)\n", file.getName(), file.getId());
^
symbol: method getId()
location: variable file of type File
3 errors
我可能正在使用过期的库，但是我去了Google的REST网站
并下载他们拥有的最新版本。
这是代码：
import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.extensions.java6.auth.oauth2.AuthorizationCodeInstalledApp;
import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver;
import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeFlow;
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.util.store.FileDataStoreFactory;
import com.google.api.services.drive.DriveScopes;
import com.google.api.services.drive.model.*;
import com.google.api.services.drive.Drive;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.List;
public class Quickstart {
/** Application name. */
private static final String APPLICATION_NAME =
"Drive API Java Quickstart";
/** Directory to store user credentials for this application. */
private static final java.io.File DATA_STORE_DIR = new java.io.File(
System.getProperty("user.home"), ".credentials/drive-java-quickstart");
/** Global instance of the {@link FileDataStoreFactory}. */
private static FileDataStoreFactory DATA_STORE_FACTORY;
/** Global instance of the JSON factory. */
private static final JsonFactory JSON_FACTORY =
JacksonFactory.getDefaultInstance();
/** Global instance of the HTTP transport. */
private static HttpTransport HTTP_TRANSPORT;
/** Global instance of the scopes required by this quickstart.
*
* If modifying these scopes, delete your previously saved credentials
* at ~/.credentials/drive-java-quickstart
*/
private static final List<String> SCOPES =
Arrays.asList(DriveScopes.DRIVE_METADATA_READONLY);
static {
try {
HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
DATA_STORE_FACTORY = new FileDataStoreFactory(DATA_STORE_DIR);
} catch (Throwable t) {
t.printStackTrace();
System.exit(1);
}
}
/**
* Creates an authorized Credential object.
* @return an authorized Credential object.
* @throws IOException
*/
public static Credential authorize() throws IOException {
// Load client secrets.
InputStream in =
Quickstart.class.getResourceAsStream("/client_secret.json");
GoogleClientSecrets clientSecrets =
GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));
// Build flow and trigger user authorization request.
GoogleAuthorizationCodeFlow flow =
new GoogleAuthorizationCodeFlow.Builder(
HTTP_TRANSPORT, JSON_FACTORY, clientSecrets, SCOPES)
.setDataStoreFactory(DATA_STORE_FACTORY)
.setAccessType("offline")
.build();
Credential credential = new AuthorizationCodeInstalledApp(
flow, new LocalServerReceiver()).authorize("user");
System.out.println(
"Credentials saved to " + DATA_STORE_DIR.getAbsolutePath());
return credential;
}
/**
* Build and return an authorized Drive client service.
* @return an authorized Drive client service
* @throws IOException
*/
public static Drive getDriveService() throws IOException {
Credential credential = authorize();
return new Drive.Builder(
HTTP_TRANSPORT, JSON_FACTORY, credential)
.setApplicationName(APPLICATION_NAME)
.build();
}
public static void main(String[] args) throws IOException {
// Build a new authorized API client service.
Drive service = getDriveService();
// Print the names and IDs for up to 10 files.
FileList result = service.files().list()
.setPageSize(10)
.setFields("nextPageToken, files(id, name)")
.execute();
List<File> files = result.getFiles();
if (files == null || files.size() == 0) {
System.out.println("No files found.");
} else {
System.out.println("Files:");
for (File file : files) {
System.out.printf("%s (%s)\n", file.getName(), file.getId());
}
}
}
}
最佳答案
我不能告诉你到底有什么问题；只是解释发生了什么。
示例-编译器抱怨：
Quickstart.java:107: error: cannot find symbol
.setPageSize(10)
相应的代码是：
FileList result = service.files().list()
.setPageSize(10)
让我们看看你得到了什么。
service是Google API的Drive类的实例。是的，当您开始研究javadoc时，该类提供了一个方法files（）;并且该调用的结果...允许调用list（）。并且
list()应该返回类List的对象。现在，您转到该类的javadoc……并且感到惊讶：没有名为setPageSize（）的方法。
因此，长话短说：编译器告诉您，您尝试对某个对象调用的方法不存在！您的反应是：
像我一样：深入探究
查看该类的文档
为了弄清楚发生了什么。
我不是该Google API的专家，但我的猜测是：这是某种版本的不兼容性。可能是您从某处复制了Quickstart源代码...但该源代码与编译器在项目设置中看到的Google API版本根本不兼容。
因此，这里的真正答案是：
确保示例代码与您使用的API版本匹配
信任编译器消息。
认真考虑：如果您需要其他人向您解释这些基本知识，那么您首先应该花一些时间来学习这些知识；例如通过工作一些基本的Java教程。当您需要其他人了解正在发生的事情时，尝试使用高级Google API毫无意义。
除此之外：您永远不会只是从某个地方放下一些代码。在尝试运行之前要做的最低限度的工作：完整阅读；并了解其中的每个电话。
我希望这能给您足够的想法来解决您的实际问题。