gradle-download-task

You can optimize builds by only downloading a file if it has changed on the server.

• Use onlyIfModified true to check the If-Modified-Since header. This requires the server to provide a Last-Modified timestamp.
• Use onlyIfModified true in combination with useETag if the server supports entity tags (ETags).

task downloadFile(type: Download) {
    src 'http://www.example.com/index.html'
    dest layout.buildDirectory
    onlyIfModified true
}

The plugin uses standard JVM system properties for proxy configuration. You can set these in your build script or via a gradle.properties file.

In build script:

System.setProperty("http.proxyHost", "www.somehost.org")

In gradle.properties:

systemProp.http.proxyHost=www.somehost.org
systemProp.http.proxyPort=8080
systemProp.http.proxyUser=userid
systemProp.http.proxyPassword=password
systemProp.http.nonProxyHosts=*.nonproxyrepos.com|localhost

To use the plugin in your Gradle build script, apply it using the plugins block.

Minimum Requirements:

• Gradle 5.x or higher
• Java 8 or higher

Note: For Gradle 2.x–4.x or Java 7, use version 4.1.2.

plugins {
    id "de.undercouch.download" version "5.7.0"
}

Version 5.0.0 introduced the following breaking changes:

• authScheme removed: The plugin now automatically detects the correct scheme based on the server response.
• download extension usage: The download extension is no longer compatible with Gradle 8 and is inconvenient in Kotlin scripts. You must now call the extension through its .run method.
  • Old: download { ... }
  • New: download.run { ... }
  • This applies to both the download and verify extensions.

To avoid unnecessary downloads, you can use the etag pattern. This allows the task to download a file only if its entity tag (ETag) on the server has changed, ensuring the local file is up-to-date.

// See groovy/etag/build.gradle for implementation

To prevent partially downloaded files from being treated as complete, you can download a file using a temporary name (e.g., <filename>.part) and rename it to the final destination only after a successful download.

// See groovy/temp-rename/build.gradle for implementation

The Download task type allows you to retrieve files during the Gradle build process. You can specify a source URL and a destination file or directory.

By default, the plugin overwrites existing files. Set overwrite false to prevent re-downloading if the file already exists.

task downloadFile(type: Download) {
    src 'http://www.example.com/index.html'
    dest layout.buildDirectory
}

You can download multiple files by defining multiple tasks or using patterns. To specify custom destination filenames for each file, use the multiple-files-rename pattern.

// See groovy/multiple-files-rename/build.gradle for implementation

You can chain a download operation with an extraction operation to download a ZIP archive and automatically extract its contents to a directory.

// See groovy/unzip/build.gradle for implementation

To download a list of files in parallel, provide a list of URLs to the src property.

Requirement: When downloading multiple files, the dest property must be a directory. If you specify a file as the destination for multiple sources, the plugin will fail.

task downloadMultipleFiles(type: Download) {
    src([
        'http://www.example.com/index.html',
        'http://www.example.com/test.html'
    ])
    dest layout.buildDirectory
}

To ensure a downloaded file is not corrupted, use the verification features. You can either use a dedicated Verify task or the verifyChecksum extension to calculate the file's checksum and compare it against a known expected value.

// See groovy/verify/build.gradle or groovy/verify-extension/build.gradle

To download and unpack a ZIP file, combine the Download task with Gradle's built-in Copy task and zipTree function.

task downloadZipFile(type: Download) {
    src 'https://github.com/michel-kraemer/gradle-download-task/archive/refs/tags/5.7.0.zip'
    dest layout.buildDirectory.file('5.7.0.zip')
}

task downloadAndUnzipFile(dependsOn: downloadZipFile, type: Copy) {
    from zipTree(downloadZipFile.dest)
    into layout.buildDirectory
}