The overall goal of Spring Boot devtools is to improve the development time. It’s available since Spring Boot version 1.3 and it includes different features among others property default, live reload, automatic restart etc.
Spring Boot devtools works by watching the classpath for any build changes and then automatically restarts the application. In Eclipse or most other IDE, every time you save, it actually builds the code. In IntelliJ, however, the code is not every time fully built when it is saved or automatically saved. In this short post, I like to demonstrate how you can configure automatic restart with IntelliJ.
First of all, you need to add devtools to your dependencies. Note that the dependency is optional in order that it is not transitively included in other projects.
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Next, we record a macro by selecting Edit → Macros → Start Macro Recording. Thereafter the following two steps must be recorded:
- File → Save All
- Build → Make Project
Once this is done, you can stop the recording via Edit → Macros → Stop Macro Recording and give a name, e.g. „Spring Boot Automatic Restart“ to the recorded macro. Next, go to keymap in the settings (File → Settings ). Copy the current keymap and rename it to „Spring Boot Keymap“ for example. Scroll down to macros and select your recorded macro. Via the context menu (right-click) add a keyboard shortcut like CTRL + S.
Whenever your Spring Boot application is running and CTRL + S is pressed, an automatic restart is done. Spring Boot devtools works with two classloaders. One that loads all the classes in the beginning and another one that only loads the changes. Thus, a startup improvement can be achieved. I observed on my machine, that the startup time is more than halved by using devtools and its automatic restart.