Hot Deployment Techniques for Spring Boot: IDEA Configuration, Spring DevTools, and JRebel

Introduction

In large projects the start‑up time and frequent restarts during debugging can waste a lot of time; hot deployment solves this by updating the running application without a full restart.

Hot Deployment Methods

Three common approaches are SpringBoot Configuration, spring‑boot‑devtools, and JRebel.

SpringBoot Configuration (IDEA)

IDEA provides a built‑in hot‑deployment option. Open Edit Configuration → Running Application Update Policies and choose either “On ‘Update’ action” (manual update via Build Project or Ctrl+F10) or “On frame deactivation” (automatic update when the IDE loses focus). For large projects the manual option is usually preferred.

spring‑boot-devtools

The devtools library uses two class loaders: one for unchanged third‑party JARs and a restart class loader for modified application classes. Adding the dependency to pom.xml enables automatic recompilation and class reloading.

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-devtools</artifactId>
    <optional>true</optional>
</dependency>

After adding the dependency, clicking Build Project triggers a hot reload, or you can configure IDEA to update automatically.

JRebel

JRebel is a JVM plugin that eliminates the build‑and‑redeploy cycle, allowing code changes to appear instantly while preserving application state. Install the plugin from the IDEA marketplace, activate it, and enable incremental compilation. Once configured, start the project with JRebel to enjoy real‑time updates.

Source: juejin.cn/post/7378328335036088359