In a previous post we learned how we can use the inputs and outputs properties to set properties or files that need to be checked to see if a task is up to date. In this post we learn how a custom task class can use annotations to set input properties, file or files and output files or dir.
For input we can use @Input, @InputFile, @InputFiles or @InputDirectory annotations. Gradle uses the properties with annotations for checking if a task is up to date. Output file or directory can be marked with @OutputFile and @OutputDirectory.
00.task generateVersionFile(type: Generate) {
01.version = '2.0'
02.outputFile = file("$project.buildDir/version.txt")
03.}
04.
05.task showContents << {
06.println generateVersionFile.outputFile.text
07.}
08.showContents.dependsOn generateVersionFile
09.
10.class Generate extends DefaultTask {
11.@Input
12.String version
13.
14.@OutputFile
15.File outputFile
16.
17.@TaskAction
18.void generate() {
19.def file = getOutputFile()
20.if (!file.isFile()) {
21.file.parentFile.mkdirs()
22.file.createNewFile()
23.}
24.file.write "Version: ${getVersion()}"
25.}
26.}
We can run our task and get the following output:
$ gradle showContents:generateVersionFile:showContentsVersion: 2.0BUILD SUCCESSFULAnd if we run it again we see the task is now up to date:
$ gradle showContents:generateVersionFile UP-TO-DATE:showContentsVersion: 2.0BUILD SUCCESSFULWe can change the version numer in our build script to 2.1 and see the output:
$ gradle showContents:generateVersionFile:showContentsVersion: 2.1BUILD SUCCESSFUL