Java Requires Chilkat v11.0.0+
Chilkat2 Java
Google Drive - Build a Local Cache of Metadata
See more Google Drive Examples
This example demonstrates how to download the metadata for all files in a Google Drive account to create a local filesystem cache with the information. The cache can be used to fetch information without having to query Google Drive.Chilkat Java Downloads
import com.chilkatsoft.chilkat2.AuthGoogle;
import com.chilkatsoft.chilkat2.Cache;
import com.chilkatsoft.chilkat2.DateTime;
import com.chilkatsoft.chilkat2.Hashtable;
import com.chilkatsoft.chilkat2.JsonArray;
import com.chilkatsoft.chilkat2.JsonObject;
import com.chilkatsoft.chilkat2.Rest;
import com.chilkatsoft.chilkat2.StringArray;
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.
boolean bAutoReconnect = true;
rest.connect("www.googleapis.com", 443, true, bAutoReconnect);
// Provide the authentication credentials (i.e. the access token)
rest.setAuthGoogle(gAuth);
// -------------------------------------------------------------------
// Initialize our cache object. Indicate the location of the root cache directory, and how many cache levels are to exist.
// For small caches (level 0) all cache files are in the root directory.
// For medium caches (level 1) cache files are located in 256 sub-directories from the root.
// For large caches (level 2) cache files are located in 256x256 sub-directories two levels down from the root.
Cache gdCache = new Cache();
gdCache.setLevel(0);
// Use a root directory that makes sense on your operating system..
gdCache.addRoot("C:/ckCache/googleDrive");
// If we are re-building the cache, we can first delete the entire contents of the cache.
int numCacheFilesDeleted = gdCache.deleteAll();
// Create a date/time object with an time 7 days from the current date/time.
DateTime dtExpire = new DateTime();
dtExpire.setFromCurrentSystemTime();
dtExpire.addDays(7);
// Indicate that we want ALL possible fields.
// If no fields are indicated, then only the basic fields are returned.
String allFields = "appProperties,capabilities,contentHints,createdTime,description,explicitlyTrashed,fileExtension,folderColorRgb,fullFileExtension,headRevisionId,iconLink,id,imageMediaMetadata,isAppAuthorized,kind,lastModifyingUser,md5Checksum,mimeType,modifiedByMeTime,modifiedTime,name,originalFilename,ownedByMe,owners,parents,permissions,properties,quotaBytesUsed,shared,sharedWithMeTime,sharingUser,size,spaces,starred,thumbnailLink,trashed,version,videoMediaMetadata,viewedByMe,viewedByMeTime,viewersCanCopyContent,webContentLink,webViewLink,writersCanShare";
// We're going to keep a master list of fileId's as we iterate over all the files in this Google Drive account.
// This master list will also be saved to the cache under the key "AllGoogleDriveFileIds".
JsonObject jsonMaster = new JsonObject();
JsonArray jsonMasterArr = new JsonArray();
jsonMaster.appendArray2("fileIds", jsonMasterArr);
// Also keep a list of file paths.
JsonArray jsonMasterPaths = new JsonArray();
jsonMaster.appendArray2("filePaths", jsonMasterPaths);
// The default page size is 100, with a max of 1000.
rest.addQueryParam("pageSize", "200");
JsonObject json = new JsonObject();
JsonObject jsonFileMetadata = new JsonObject();
int i = 0;
int numFiles = 0;
// Send the request for the 1st page.
String jsonResponse = rest.fullRequestNoBody("GET", "/drive/v3/files");
int pageNumber = 1;
String pageToken = "";
boolean bContinueLoop = rest.getLastMethodSuccess() && (rest.getResponseStatusCode() == 200);
while (bContinueLoop) {
System.out.println("---- Page " + pageNumber + " ----");
json.load(jsonResponse);
numFiles = json.sizeOfArray("files");
i = 0;
while (i < numFiles) {
// Add this file ID to the master list.
json.setI(i);
jsonMasterArr.addStringAt(-1, json.stringOf("files[i].id"));
i = i + 1;
}
// Get the next page of files.
// If the "nextPageToken" is present in the JSON response, then use it in the "pageToken" parameter
// for the next request. If no "nextPageToken" was present, then this was the last page of files.
pageToken = json.stringOf("nextPageToken");
bContinueLoop = false;
boolean bHasMorePages = json.getLastMethodSuccess();
if (bHasMorePages) {
rest.clearAllQueryParams();
rest.addQueryParam("pageSize", "200");
rest.addQueryParam("pageToken", pageToken);
jsonResponse = rest.fullRequestNoBody("GET", "/drive/v3/files");
bContinueLoop = rest.getLastMethodSuccess() && (rest.getResponseStatusCode() == 200);
pageNumber = pageNumber + 1;
}
}
// Check to see if the above loop exited with errors...
if (!rest.getLastMethodSuccess()) {
System.out.println(rest.getLastErrorText());
return;
}
// Check to see if the above loop exited with errors...
// A successful response will have a status code equal to 200.
if (rest.getResponseStatusCode() != 200) {
System.out.println("response status code = " + rest.getResponseStatusCode());
System.out.println("response status text = " + rest.getResponseStatusText());
System.out.println("response header: " + rest.getResponseHeader());
System.out.println("response JSON: " + jsonResponse);
return;
}
// Iterate over the file IDs and download the metadata for each, saving each to the cache...
// Also, keep in-memory hash entries of the name and parent[0] so we can quickly
// build the path-->fileId cache entries. (Given that the Google Drive REST API uses
// fileIds, this gives us an easy way to lookup a fileId based on a filePath.)
Hashtable hashTable = new Hashtable();
// Set the capacity of the hash table to something reasonable for the number of files
// to be hashed.
hashTable.clearWithNewCapacity(521);
StringBuilder sbPathForFileId = new StringBuilder();
// Used for storing the file name and parents[0] in the hashTable.
StringArray saFileInfo = new StringArray();
saFileInfo.setUnique(false);
String fileId = "";
numFiles = jsonMaster.sizeOfArray("fileIds");
i = 0;
while (i < numFiles) {
jsonMaster.setI(i);
fileId = jsonMaster.stringOf("fileIds[i]");
sbPathForFileId.setString("/drive/v3/files/");
sbPathForFileId.append(fileId);
rest.clearAllQueryParams();
rest.addQueryParam("fields", allFields);
jsonResponse = rest.fullRequestNoBody("GET", sbPathForFileId.getAsString());
if ((!rest.getLastMethodSuccess()) || (rest.getResponseStatusCode() != 200)) {
// Force an exit of this loop..
numFiles = 0;
}
// Save this file's metadata to the local cache.
// The lookup key is the fileId.
gdCache.saveTextDt(fileId, dtExpire, "", jsonResponse);
// Get this file's name and parent[0], and put this information
// in our in-memory hashtable to be used below..
json.load(jsonResponse);
saFileInfo.clear();
saFileInfo.append(json.stringOf("name"));
saFileInfo.append(json.stringOf("parents[0]"));
hashTable.addStr(fileId, saFileInfo.serialize());
System.out.println(json.stringOf("name") + ", " + json.stringOf("parents[0]"));
i = i + 1;
}
// Check to see if the above loop exited with errors...
if (!rest.getLastMethodSuccess()) {
System.out.println(rest.getLastErrorText());
return;
}
// Check to see if the above loop exited with errors...
// A successful response will have a status code equal to 200.
if (rest.getResponseStatusCode() != 200) {
System.out.println("response status code = " + rest.getResponseStatusCode());
System.out.println("response status text = " + rest.getResponseStatusText());
System.out.println("response header: " + rest.getResponseHeader());
System.out.println("response JSON: " + jsonResponse);
return;
}
// Now that all the fileId's are in the cache, let's build the directory path
// for each fileID.
// (Technically, a fileId can have multiple parents, which means it can be in multiple directories
// at once. This is only going to build directory paths following the 0'th parent ID in the parents list.)
// The directory path for files in "My Drive" will be just the filename.
// For files in sub-directories, the path will be relative, such as "subdir1/subdir2/something.pdf"
//
System.out.println("---- building paths ----");
StringBuilder sbPath = new StringBuilder();
numFiles = jsonMaster.sizeOfArray("fileIds");
i = 0;
while (i < numFiles) {
jsonMaster.setI(i);
sbPath.clear();
fileId = jsonMaster.stringOf("fileIds[i]");
boolean bFinished = false;
while (!bFinished) {
saFileInfo.clear();
saFileInfo.appendSerialized(hashTable.lookupStr(fileId));
// Append this file or directory name.
sbPath.prepend(saFileInfo.getString(0));
// Get the parent fileId
fileId = saFileInfo.getString(1);
// If this fileId is not in the hashtable, then it's the fileId for "My Drive", and we are finished.
if (!hashTable.contains(fileId)) {
bFinished = true;
} else {
sbPath.prepend("/");
}
}
System.out.println(i + ": " + sbPath.getAsString());
// Store the filePath --> fileId mapping in our local cache.
fileId = jsonMaster.stringOf("fileIds[i]");
gdCache.saveTextDt(sbPath.getAsString(), dtExpire, "", fileId);
jsonMasterPaths.addStringAt(-1, sbPath.getAsString());
i = i + 1;
}
// Save the master list of file IDs and file paths to the local cache.
jsonMaster.setEmitCompact(false);
String strJsonMaster = jsonMaster.emit();
gdCache.saveTextNoExpire("AllGoogleDriveFileIds", "", strJsonMaster);
System.out.println("JSON Master Record:");
System.out.println(strJsonMaster);
// The JSON Master Cache Record looks something like this:
// An application can load the JSON master record and iterate over all the files
// in Google Drive by file ID, or by path.
// {
// "fileIds": [
// "0B53Q6OSTWYolQlExSlBQT1phZXM",
// "0B53Q6OSTWYolVHRPVkxtYWFtZkk",
// "0B53Q6OSTWYolRGZEV3ZGUTZfNFk",
// "0B53Q6OSTWYolS2FXSjliMXQxSU0",
// "0B53Q6OSTWYolZUhxckMzb0dRMzg",
// "0B53Q6OSTWYolbUF6WS1Gei1oalk",
// "0B53Q6OSTWYola296ODZUSm5GYU0",
// "0B53Q6OSTWYolbTE3c3J5RHBUcHM",
// "0B53Q6OSTWYolTmhybWJSUGd5Q2c",
// "0B53Q6OSTWYolY2tPU1BnYW02T2c",
// "0B53Q6OSTWYolTTBBR2NvUE81Zzg",
// ],
// "filePaths": [
// "testFolder/abc/123/pigs.json",
// "testFolder/starfish20.jpg",
// "testFolder/penguins2.jpg",
// "testFolder/starfish.jpg",
// "testFolder/abc/123/starfish.jpg",
// "testFolder/abc/123/penguins.jpg",
// "testFolder/abc/123",
// "testFolder/abc",
// "testFolder/testHello.txt",
// "testFolder",
// "helloWorld.txt",
// ]
// }
System.out.println("Entire cache rebuilt...");
}
}