深入解析Spring Boot热部署与性能优化实践指南

// RestartLauncher.java (核心入口)
public class RestartLauncher {
    public static void main(String[] args) throws Exception {
        PollingAppStartup startup = new PollingAppStartup();
        RestartClassLoader classLoader = new RestartClassLoader(getUrls(), getParent());
        Thread.currentThread().setContextClassLoader(classLoader);
        // 启动业务主类
        Class<?> mainClass = classLoader.loadClass(getMainClassName());
        Method main = mainClass.getMethod("main", String[].class);
        main.invoke(null, new Object[] { args });
    }
}
// RestartClassLoader.java (隔离业务和依赖)
class RestartClassLoader extends URLClassLoader {
    private final URL[] baseUrls;
    private final List<Resource> restartResources;
    RestartClassLoader(URL[] baseUrls, ClassLoader parent) {
        super(new URL[0], parent);
        this.baseUrls = baseUrls;
        this.restartResources = ...;
    }
    @Override
    protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
        // 先委托父加载关键类，再自行加载业务类
        if (!isRestartClass(name)) {
            return super.loadClass(name, resolve);
        }
        // 从 baseUrls 加载新编译的类文件
        byte[] classData = loadBytes(name);
        Class<?> cls = defineClass(name, classData, 0, classData.length);
        if (resolve) {
            resolveClass(cls);
        }
        return cls;
    }
}

my-app
├── pom.xml
├── src
│   ├── main
│   │   ├── java
│   │   │   └── com.example.demo
│   │   │       └── DemoApplication.java
│   │   └── resources
│   │       └── application.yml
└── target
    └── classes

<!-- pom.xml -->
<dependencies>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-devtools</artifactId>
    <optional>true</optional>
  </dependency>
  <!-- 生产环境不启用 DevTools -->
</dependencies>

# application.yml
spring:
  devtools:
    restart:
      enabled: true       # 默认开启
      exclude:
        - static/**
        - public/**      # 静态资源无需重启