每次构建（包装）之前都要清洁

Question

Regardless of build tool, I have seen people doing a clean task/phase before every time they do package/compile or ... is it really necessary? Dose build tools use reuse artifacts of previous builds?

Answer 1

Most of the time you see clean install as the default command, but I would encourage everybody to use verify instead.

When executing clean the target-folder is removed which makes it impossible to do incremental builds. Plugins have enough information to detect if they should do their action. For instance: the maven-compiler-plugin compares the java sourcesfiles and the compiled classfiles (and other things) to see if files needs to be (re)compiled. If you think that a plugin is not working correctly with incremental builds, please file an issue for that plugin.

The install was often required with multimodules in Maven2, but Maven3 is capable to resolve these inner module dependency references. The only thing 'install' does is copying artifacts to the local repository (=IO=expensive). And it'll make your local repo look different compared to your coworkers, which might give different results during builds. Better to let a buildserver push those artifacts to the shared remote repositories and let every pull those SNAPSHOTs from there. Only in rare cases calling install is valid (experienced Maven users know when :) ), so instead please use verify .