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Karl Rieb
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Add longpoll example and made network read timeouts configurable for StandardHttpRequestor.
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‎ChangeLog.txt‎

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- Make read timeouts more easily configurable for StandardHttpRequestor.
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- Add longpoll example.
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- Fix android example bugs and linter warnings
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- Fix compilation error
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- Fix upload failure bug

‎examples/longpoll/.gitignore‎

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/target

‎examples/longpoll/pom.xml‎

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<project xmlns="http://maven.apache.org/POM/4.0.0"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
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http://maven.apache.org/maven-v4_0_0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<name>List Folder Longpoll Example (Dropbox Core API SDK)</name>
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<artifactId>examples-longpoll</artifactId>
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<packaging>jar</packaging>
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<parent>
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<groupId>com.dropbox.core</groupId>
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<artifactId>examples</artifactId>
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<version>0-SNAPSHOT</version>
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<relativePath>../pom.xml</relativePath>
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</parent>
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<build>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-dependency-plugin</artifactId>
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<executions>
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<execution>
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<phase>compile</phase>
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<goals>
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<goal>build-classpath</goal>
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</goals>
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</execution>
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</executions>
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</plugin>
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</plugins>
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</build>
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</project>

‎examples/longpoll/src/com/dropbox/core/examples/longpoll/Main.java‎

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package com.dropbox.core.examples.longpoll;
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import com.dropbox.core.DbxApiException;
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import com.dropbox.core.DbxAuthInfo;
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import com.dropbox.core.DbxException;
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import com.dropbox.core.DbxRequestConfig;
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import com.dropbox.core.DbxWebAuth;
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import com.dropbox.core.json.JsonReader;
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import com.dropbox.core.http.StandardHttpRequestor;
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import com.dropbox.core.v2.DbxClientV2;
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import com.dropbox.core.v2.DbxFiles;
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import java.io.IOException;
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import java.util.Locale;
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import java.util.concurrent.TimeUnit;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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/**
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* An example command-line application that demonstrates how to use
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* longpolling to watch for file changes in a Dropbox account.
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*/
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public class Main {
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/**
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* Will perform longpoll request for changes in the user's Dropbox
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* account and display those changes. This is more efficient that
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* periodic polling the endpoint.
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*/
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public static void longpoll(DbxAuthInfo auth, String path) throws IOException {
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long longpollTimeoutSecs = TimeUnit.MINUTES.toSeconds(2);
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// need 2 Dropbox clients for making calls:
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//
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// (1) One for longpoll requests, with its read timeout set longer than our polling timeout
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// (2) One for all other requests, with its read timeout set to the default, shorter timeout
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//
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StandardHttpRequestor.Config config = StandardHttpRequestor.Config.DEFAULT_INSTANCE;
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StandardHttpRequestor.Config longpollConfig = config.copy()
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.withReadTimeout(longpollTimeoutSecs + 1, TimeUnit.SECONDS)
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.build();
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DbxClientV2 dbxClient = createClient(auth, config);
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DbxClientV2 dbxLongpollClient = createClient(auth, longpollConfig);
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try {
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// We only care about file changes, not existing files, so grab latest cursor for this
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// path and then longpoll for changes.
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String cursor = getLatestCursor(dbxClient, path);
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System.out.println("Longpolling for changes... press CTRL-C to exit.");
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while (true) {
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// will block for longpollTimeoutSecs or until a change is made in the folder
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DbxFiles.ListFolderLongpollResult result = dbxLongpollClient.files.listFolderLongpoll(cursor, longpollTimeoutSecs);
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// we have changes, list them
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if (result.changes) {
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cursor = printChanges(dbxClient, cursor);
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}
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// we were asked to back off from our polling, wait the requested amount of seconds
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// before issuing another longpoll request.
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if (result.backoff != null) {
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System.out.printf("\n\nBacking off for %d seconds\n\n", result.backoff);
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try {
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Thread.sleep(TimeUnit.SECONDS.toMillis(result.backoff));
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} catch (InterruptedException ex) {
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System.exit(0);
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}
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}
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}
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} catch (DbxApiException ex) {
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// if a user message is available, try using that instead
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String message = ex.userMessage != null ? ex.userMessage.toString() : ex.getMessage();
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System.err.println("Error making API call: " + message);
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System.exit(1);
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return;
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} catch (DbxException ex) {
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System.err.println("Error making API call: " + ex.getMessage());
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System.exit(1);
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return;
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}
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}
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/**
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* Create a new Dropbox client using the given authentication
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* information and HTTP client config.
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*
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* @param auth Authentication information
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* @param config HTTP request configuration
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*
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* @return new Dropbox V2 client
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*/
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private static DbxClientV2 createClient(DbxAuthInfo auth, StandardHttpRequestor.Config config) {
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String clientUserAgentId = "examples-longpoll";
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String userLocale = Locale.getDefault().toString();
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StandardHttpRequestor requestor = new StandardHttpRequestor(config);
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DbxRequestConfig requestConfig = new DbxRequestConfig(clientUserAgentId, userLocale, requestor);
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return new DbxClientV2(requestConfig, auth.accessToken, auth.host);
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}
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/**
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* Returns latest cursor for listing changes to a directory in
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* Dropbox with the given path.
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*
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* @param dbxClient Dropbox client to use for fetching the latest cursor
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* @param path path to directory in Dropbox
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*
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* @return cursor for listing changes to the given Dropbox directory
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*/
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private static String getLatestCursor(DbxClientV2 dbxClient, String path)
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throws DbxApiException, DbxException {
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DbxFiles.ListFolderGetLatestCursorResult result = dbxClient.files.listFolderGetLatestCursorBuilder(path)
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.includeDeleted(true)
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.includeMediaInfo(false)
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.recursive(true)
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.start();
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return result.cursor;
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}
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/**
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* Prints changes made to a folder in Dropbox since the given
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* cursor was retrieved.
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*
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* @param dbxClient Dropbox client to use for fetching folder changes
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* @param cursor lastest cursor received since last set of changes
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*
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* @return latest cursor after changes
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*/
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private static String printChanges(DbxClientV2 client, String cursor)
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throws DbxApiException, DbxException {
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while (true) {
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DbxFiles.ListFolderResult result = client.files.listFolderContinue(cursor);
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for (DbxFiles.Metadata metadata : result.entries) {
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String type;
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String details;
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if (metadata instanceof DbxFiles.FileMetadata) {
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DbxFiles.FileMetadata fileMetadata = (DbxFiles.FileMetadata) metadata;
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type = "file";
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details = "(rev=" + fileMetadata.rev + ")";
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} else if (metadata instanceof DbxFiles.FolderMetadata) {
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DbxFiles.FolderMetadata folderMetadata = (DbxFiles.FolderMetadata) metadata;
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type = "folder";
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details = folderMetadata.sharingInfo != null ? "(shared)" : "";
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} else if (metadata instanceof DbxFiles.DeletedMetadata) {
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type = "deleted";
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details = "";
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} else {
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throw new IllegalStateException("Unrecognized metadata type: " + metadata.getClass());
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}
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System.out.printf("\t%10s %24s \"%s\"\n", type, details, metadata.pathLower);
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}
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// update cursor to fetch remaining results
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cursor = result.cursor;
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if (!result.hasMore) {
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break;
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}
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}
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return cursor;
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}
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public static void main(String[] args) throws IOException {
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// Only display important log messages.
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Logger.getLogger("").setLevel(Level.WARNING);
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if (args.length == 0) {
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System.out.println("");
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System.out.println("Usage: COMMAND <auth-file> <dropbox-path>");
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System.out.println("");
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System.out.println(" <auth-file>: An \"auth file\" that contains the information necessary to make");
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System.out.println(" an authorized Dropbox API request. Generate this file using the \"authorize\"");
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System.out.println(" example program.");
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System.out.println("");
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System.out.println(" <dropbox-path>: The path on Dropbox to watch for changes.");
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System.out.println("");
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return;
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}
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if (args.length != 2) {
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System.err.println("Expecting exactly 2 arguments, got " + args.length + ".");
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System.err.println("Run with no arguments for help.");
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System.exit(1); return;
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}
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String authFile = args[0];
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String path = args[1];
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// Read auth info file.
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DbxAuthInfo auth;
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try {
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auth = DbxAuthInfo.Reader.readFromFile(authFile);
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}
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catch (JsonReader.FileLoadException ex) {
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System.err.println("Error loading <auth-file>: " + ex.getMessage());
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System.exit(1); return;
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}
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longpoll(auth, path);
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}
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}

‎examples/pom.xml‎

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<modules>
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<module>authorize</module>
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<module>account-info</module>
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<module>longpoll</module>
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<module>upload-file</module>
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<module>web-file-browser</module>
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<module>upgrade-oauth1-token</module>

‎src/com/dropbox/core/DbxRequestConfig.java‎

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/**
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* The {@link HttpRequestor} implementation to use when making
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* HTTP requests to the Dropbox API servers. If you don't specify one, this defaults to
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* {@link StandardHttpRequestor#Instance}.
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* {@link StandardHttpRequestor#INSTANCE}.
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*/
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public final HttpRequestor httpRequestor;
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*/
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public DbxRequestConfig(String clientIdentifier, String userLocale)
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{
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this(clientIdentifier, userLocale, StandardHttpRequestor.Instance);
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this(clientIdentifier, userLocale, StandardHttpRequestor.INSTANCE);
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}
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}

‎src/com/dropbox/core/http/HttpRequestor.java‎

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import java.util.Map;
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import java.util.TreeMap;
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import java.util.concurrent.TimeUnit;
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/**
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* An interface that the Dropbox client library uses to make HTTP requests.
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* If you're fine with the standard Java {@link java.net.HttpURLConnection}
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* implementation, then just use {@link StandardHttpRequestor#Instance}.
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* implementation, then just use {@link StandardHttpRequestor#INSTANCE}.
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*/
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public abstract class HttpRequestor
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{
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/**
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* Default timeout, in milliseconds, for opening a connection to a network resource.
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*
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* A value of 0 indicates the timeout should be disabled.
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*/
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public static final long DEFAULT_CONNECT_TIMEOUT_MILLIS = TimeUnit.SECONDS.toMillis(20);
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/**
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* Default timeout, in milliseconds, for receiving a response from a network resource.
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*
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* A value of 0 indicates the timeout should be disabled.
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*/
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public static final long DEFAULT_READ_TIMEOUT_MILLIS = TimeUnit.SECONDS.toMillis(20);
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public abstract Response doGet(String url, Iterable<Header> headers) throws IOException;
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public abstract Uploader startPost(String url, Iterable<Header> headers) throws IOException;
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public abstract Uploader startPut(String url, Iterable<Header> headers) throws IOException;
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/**
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* The default socket connect/read/write timeout.
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*/
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public static final int DefaultTimeoutMillis = 20 * 1000;
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/**
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* A simple structure holding an HTTP header, which is key/value pair.
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* Used with {@link HttpRequestor}.

‎src/com/dropbox/core/http/OkHttpRequestor.java‎

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* You can only use this if your project includes the OkHttp library.
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*
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* <p>
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* To use this, pass {@link #Instance} to the {@link com.dropbox.core.DbxRequestConfig} constructor.
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* To use this, pass {@link #INSTANCE} to the {@link com.dropbox.core.DbxRequestConfig} constructor.
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* </p>
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*/
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public class OkHttpRequestor extends HttpRequestor
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{
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/**
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* A thread-safe instance of {@code OkHttpRequestor} that connects directly
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* (as opposed to using a proxy).
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*/
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public static final OkHttpRequestor INSTANCE = new OkHttpRequestor(defaultOkHttpClient());
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private final OkHttpClient client;
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private static OkHttpClient defaultOkHttpClient()
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{
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OkHttpClient client = new OkHttpClient();
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client.setConnectTimeout(DefaultTimeoutMillis, TimeUnit.MILLISECONDS);
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client.setReadTimeout(DefaultTimeoutMillis, TimeUnit.MILLISECONDS);
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client.setWriteTimeout(DefaultTimeoutMillis, TimeUnit.MILLISECONDS);
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client.setConnectTimeout(DEFAULT_CONNECT_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS);
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client.setReadTimeout(DEFAULT_READ_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS);
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client.setWriteTimeout(DEFAULT_READ_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS);
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return client;
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}
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/**
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* A thread-safe instance of {@code OkHttpRequestor} that connects directly
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* (as opposed to using a proxy).
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*/
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public static final OkHttpRequestor Instance = new OkHttpRequestor(defaultOkHttpClient());
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public OkHttpRequestor(OkHttpClient client)
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{
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this.client = client;

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