Gradle Download Task

This is a simple download task for Gradle. It displays progress information just as Gradle does when it retrieves an artifact from a repository.

The plugin has been sucessfully tested with Gradle 1.0 up to 4.8. It should work with newer versions as well.

Apply plugin configuration

Gradle 2.1 and higher

plugins {
    id "de.undercouch.download" version "3.4.3"
}

Gradle 1.x and 2.0

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'de.undercouch:gradle-download-task:3.4.3'
    }
}

apply plugin: 'de.undercouch.download'

Usage

After you applied the plugin configuration (see above) you can use the Download task as follows:

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

By default, the plugin always performs a download even if the destination file already exists. If you want to prevent files from being downloaded again, use the overwrite flag (see description below).

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

As an alternative to the Download task, you may also use the download extension to retrieve a file anywhere in your build script:

task myTask << {
    //do something ...
    //... then download a file
    download {
        src 'http://www.example.com/index.html'
        dest buildDir
        overwrite false
    }
    //... do something else
}

Examples

Only download a file if it has been modified on the server

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

Note that this feature depends on the server and whether it supports the If-Modified-Since request header and if it provides a Last-Modified timestamp in its response.

Sequentially download a list of files to a directory

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

Please note that you have to specify a directory as destination if you download multiple files. Otherwise the plugin will fail.

Download files from a directory

If you want to download all files from a directory and the server provides a simple directory listing you can use the following code:

task downloadDirectory {
    def dir = 'http://central.maven.org/maven2/de/undercouch/gradle-download-task/1.0/'
    def urlLister = new org.apache.ivy.util.url.ApacheURLLister()
    def files = urlLister.listFiles(new URL(dir))
    download {
       src files
       dest buildDir
    }
}

Download and extract a ZIP file

To download and unpack a ZIP file you can combine the download task plugin with Gradle's built-in support for ZIP files:

task downloadZipFile(type: Download) {
    src 'https://github.com/michel-kraemer/gradle-download-task/archive/1.0.zip'
    dest new File(buildDir, '1.0.zip')
}

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

More examples

Please have a look at the examples directory for more code samples. You can also read my blog post about common recipes for gradle-download-task.

Download task

The download task and the extension support the following properties.

General

src: The URL from which to retrieve the file. Can be a list of URLs if multiple files shoud be downloaded. (required)
dest: The file or directory where to store the file (required)
quiet: true if progress information should not be displayed (default: false)
overwrite: true if existing files should be overwritten (default: true)
onlyIfModified (alias: onlyIfNewer): true if the file should only be downloaded if it has been modified on the server since the last download (default: false)

Tip! You may provide Groovy Closures to the src and dest properties to calculate their value at runtime.

Connection

acceptAnyCertificate: true if HTTPS certificate verification errors should be ignored and any certificate (even an invalid one) should be accepted. (default: false)
compress: true if compression should be used during download (default: true)
header: The name and value of a request header to set when making the download request (optional)
headers: A map of request headers to set when making the download request (optional)
timeout: The maximum number of milliseconds to wait until a connection is established or until the server returns data. A value of 0 (zero) means infinite timeout. A negative value is interpreted as undefined. (default: -1)

Authentication

username: The username for Basic or Digest authentication (optional)
password: The password for Basic or Digest authentication (optional)
credentials: The credentials to use for authentication. This property is an alternative to username and password. The value is expected to be an instance of Credentials. (optional)
authScheme: The authentication scheme to use. Either a string (valid values are Basic and Digest) or an instance of AuthScheme. If credentials are configured (either through username and password or through credentials) the default value of this property will be Basic. Otherwise this property has no default value. (optional)

Advanced

downloadTaskDir

The directory where the plugin stores information that should persist between builds. It will only be created if necessary. (default: ${buildDir}/download-task)

tempAndMove

true if the file should be downloaded to a temporary location and, upon successful execution, moved to the final location. If overwrite is set to false, this flag is useful to avoid partially downloaded files if Gradle is forcefully closed or the system crashes. Note that the plugin always deletes partial downloads on connection errors, regardless of the value of this flag. The default temporary location can be configured with the downloadTaskDir property. (default: false)

useETag

Use this flag in combination with onlyIfModified. If both flags are true the plugin will check a file's timestamp as well as its entity tag (ETag) and only download it if it has been modified on the server since the last download. The plugin can differentiate between strong and weak ETags. Possible values are:

false (default): Do not use the ETag
true: Use the ETag but display a warning if it is weak
"all": Use the ETag and do not display a warning if it is weak
"strongOnly": Only use the ETag if it is strong

cachedETagsFile

The location of the file that keeps entity tags (ETags) received from the server. (default: ${downloadTaskDir}/etags.json)

requestInterceptor

An instance of HttpRequestInterceptor. Can be used to intercept and modify outgoing HTTP requests before they are sent to the server. (optional)

responseInterceptor

An instance of HttpResponseInterceptor. Can be used to intercept and manipulate HTTP responses from the server before they are handled by the plugin. (optional)

Verify task

The plugin also provides a Verify task that can be used to check the integrity of a downloaded file by calculating its checksum and comparing it to a pre-defined value. The task succeeds if the file's checksum equals the given value and fails if it doesn't.

Use the task as follows:

task verifyFile(type: Verify) {
    src new File(buildDir, 'file.ext')
    algorithm 'MD5'
    checksum 'ce114e4501d2f4e2dcea3e17b546f339'
}

You can combine the download task and the verify task as follows:

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

task verifyFile(type: Verify, dependsOn: downloadFile) {
    src new File(buildDir, 'index.html')
    algorithm 'MD5'
    checksum '09b9c392dc1f6e914cea287cb6be34b0'
}

The verify task supports the following properties:

src: The file to verify (required)
checksum: The actual checksum to verify against (required)
algorithm: The algorithm to use to compute the checksum. See the list of algorithm names for more information. (default: MD5)

Proxy configuration

You can configure a proxy server by setting standard JVM system properties. The plugin uses the same system properties as Gradle. You can set them in the build script directly. For example, the proxy host can be set as follows:

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

Alternatively, you can set the properties in a gradle.properties file like this:

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

Put this file in your project's root directory or in your Gradle home directory.

HTTPS is also supported:

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

License

The plugin is licensed under the Apache License, Version 2.0.

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

wangfuda / gradle-download-task