10 recipes for gradle-download-task
I received a couple of requests lately concerning common problems when downloading files in Gradle build scripts using gradle-download-task. Almost all of these issues could be solved by just using gradle-download-task the right way instead of extending the plugin. I have collected a number of example build scripts for these issues over the last months, and I thought it would be a good idea to summarize them here.
For those of you who don’t know what gradle-download-task is: the plugin
Download task that displays progress information while downloading
files, just like Gradle does when it fetches an artifact from a repository.
Recipe #1: download a single file
This is the simplest use case for gradle-download-task. The following snippet downloads a single file to the project’s build directory.
Alternatively, use the
download extension to download a file anywhere in your
Recipe #2: download multiple files
If you want to download multiple files at once to the project’s build directory, use the following snippet.
Complete example build script: multiple-files/build.gradle
Recipe #3: download and rename multiple files
Download multiple files into a target directory and specify a destination file name for each of them as follows:
Complete example build script: multiple-files-rename/build.gradle
Recipe #4: custom HTTP headers
Download a single file and specify a custom HTTP header with the following snippet.
Complete example build script: custom-header/build.gradle
Recipe #5: download all files from a directory
The following snippet downloads all files from a directory on a server. It makes use of Ivy’s URL lister to read the server’s directory listing.
You also need to include a build script dependency to Apache Ivy to make this recipe work. Put the following code right at the beginning of your build script:
Complete example build script: directory/build.gradle
Recipe #6: mirror servers
Download a single file from a mirror server with the following snippet. It first configures multiple mirror servers and then uses the first one that is working.
Complete example build script: mirrors/build.gradle
Recipe #7: Lazily evaluate
The following snippet downloads a single file. It uses Groovy closures to
generate values for the
dest properties at runtime.
Complete example build script: lazy-src-and-dest/build.gradle
Recipe #8: temporary .part file (i.e. download and rename)
This snippet downloads a single file conditionally using a temporary file name
<filename>.part). It renames the file afterwards if the download was
.part file is always overwritten if it exists (e.g. from a
previous attempt to download the file).
Complete example build script: temp-rename/build.gradle
Recipe #9: unzip downloaded file
The following two tasks download a ZIP file and extract its contents to the project’s build directory.
Complete example build script: unzip/build.gradle
Recipe #10: verify checksum of downloaded file
The final snippet consists of two tasks that first download a file and then verify its checksum.
Complete example build script: verify/build.gradle
At the time of writing this post, the gradle-download-task repository contains 14 example build scripts in both Groovy and Kotlin. You can find them in the examples directory:
More examples will be added in the future, so make sure to check this directory too. If you have other snippets worth adding to the list, send me a pull request on GitHub or post a comment below. Thanks!
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Posted by Michel Krämer
on 3 April 2016
I’m happy to announce a new version of the popular gradle-download-task. The plugin’s core has been completely rewritten. It now supports proxy servers and creates target directories automatically. Updating is recommended for all users.
I’ve just released gradle-download-task 5.0.0. The new version now downloads multiple files in parallel, executes concurrently with other build tasks, and offers better support for Kotlin and Gradle 8.
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