Gradle Goodness:add Incremental Build support to Custom Tasks with Annotations

In a previous post we learned how we can use the inputs and outputs properties to set properties or file s, need to being checked to see if a task was up to date. In this post we learn what a custom task class can use annotations to set input properties, file or files and output files or dir.

For-Input we can @Input use @InputFile , @InputFiles or @InputDirectory annotations. Gradle uses the properties with annotations for checking if a task was up to date. Output file or directory can be marked with @OutputFile and @OutputDirectory .

View Sourceprint? 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 :showContents Version: 2.0  BUILD SUCCESSFUL

And if we run it again we see that the task is now a to date:

$ gradle showContents :generateVersionFile UP-TO-DATE :showContents Version: 2.0  BUILD SUCCESSFUL

We can change the version of Numer in our build script to 2.1 and see the output:

$ gradle showContents :generateVersionFile :showContents Version: 2.1  BUILD SUCCESSFUL

Gradle Goodness:add Incremental Build support to Custom Tasks with Annotations