Module page.codeberg.friedolyn.Friedolyn

Package page.codeberg.friedolyn.util

Class FileDownloader

java.lang.Object

page.codeberg.friedolyn.util.FileDownloader

public class FileDownloader
extends Object

A utility class that downloads files from the internet.

See Also:

• download(URL, File)
• download(URL, File, String, boolean, boolean)

Constructor Summary

Constructors

Constructor	Description
FileDownloader()

Method Summary

Modifier and Type	Method	Description
static void	download(@NonNull URL url, @NonNull File target)	Retrieves a file of arbitrary format from the server available at the given web address to the specified destination.
static void	download(@NonNull URL url, @NonNull File target, @NonNull String userAgent, boolean doNotTrack, boolean globalPrivacyControl)	Retrieves a file of arbitrary format from the server available at the given web address to the specified destination.
private static Optional<byte[]>	readFile(File file)	Extracts the content of the given local file.
private static void	writeFile(byte[] content, File target)	Saves the content to the given local file.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

FileDownloader

public FileDownloader()

Method Details

download

public static void download(@NonNull
 @NonNull URL url,
 @NonNull
 @NonNull File target)
                     throws RuntimeException,
IOException

Retrieves a file of arbitrary format from the server available at the given web address to the specified destination. Uses Friedolyn on the default platform as the user agent. Will not send the Do Not Track or Global Privacy Control header with the HTTP request.

Parameters:

url - The publicly available web address of the file to be downloaded. Must not require authentication, JavaScript execution, user interaction, cookies or a browser engine.

target - The file to which the downloaded content will be written. Must be a file, not a directory.

Throws:

RuntimeException - If the target file is not a file or if an error occurs while creating the HTTP client or the HTTP request.

IOException - If an error occurs while downloading the file.

download

public static void download(@NonNull
 @NonNull URL url,
 @NonNull
 @NonNull File target,
 @NonNull
 @NonNull String userAgent,
 boolean doNotTrack,
 boolean globalPrivacyControl)
                     throws RuntimeException,
IOException

Retrieves a file of arbitrary format from the server available at the given web address to the specified destination.

Parameters:

url - The publicly available web address of the file to be downloaded. Must not require authentication, JavaScript execution, user interaction, cookies or a browser engine.

target - The file to which the downloaded content will be written. Must be a file, not a directory.

userAgent - The user agent string to be sent with the HTTP request.

doNotTrack - Whether to send the Do Not Track header with the HTTP request. No header will be sent if set to false.

globalPrivacyControl - Whether to send the Global Privacy Control header with the HTTP request. No header will be sent if set to false.

Throws:

RuntimeException - If the target file is not a file or if an error occurs while creating the HTTP client or the HTTP request.

IOException - If an error occurs while downloading the file.

readFile

private static Optional<byte[]> readFile(File file)

Extracts the content of the given local file.

Parameters:

file - The file to be read. May be of any format, i.e. plain text (TXT, JSON, CSV etc.) or binary (PNG, PDF etc.)

Returns:

The content of the file. Empty if the file does not exist or an error occurs while reading it.

writeFile

private static void writeFile(byte[] content,
 File target)

Saves the content to the given local file.

Parameters:

content - The data to be written to the file. May be of any format, i.e. plain text (TXT, JSON, CSV etc.). Will not be modified.

target - The file to which the given data will be written.