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org.springframework.context.ApplicationContextInitializer扩展点
package org.springframework.context;
/**
* Callback interface for initializing a Spring {@link ConfigurableApplicationContext}
* prior to being {@linkplain ConfigurableApplicationContext#refresh() refreshed}.
*
* <p>Typically used within web applications that require some programmatic initialization
* of the application context. For example, registering property sources or activating
* profiles against the {@linkplain ConfigurableApplicationContext#getEnvironment()
* context's environment}. See {@code ContextLoader} and {@code FrameworkServlet} support
* for declaring a "contextInitializerClasses" context-param and init-param, respectively.
*
* <p>{@code ApplicationContextInitializer} processors are encouraged to detect
* whether Spring's {@link org.springframework.core.Ordered Ordered} interface has been
* implemented or if the {@link org.springframework.core.annotation.Order @Order}
* annotation is present and to sort instances accordingly if so prior to invocation.
*
* @author Chris Beams
* @since 3.1
* @param <C> the application context type
* @see org.springframework.web.context.ContextLoader#customizeContext
* @see org.springframework.web.context.ContextLoader#CONTEXT_INITIALIZER_CLASSES_PARAM
* @see org.springframework.web.servlet.FrameworkServlet#setContextInitializerClasses
* @see org.springframework.web.servlet.FrameworkServlet#applyInitializers
*/
@FunctionalInterface
public interface ApplicationContextInitializer<C extends ConfigurableApplicationContext> {
/**
* Initialize the given application context.
* @param applicationContext the application to configure
*/
void initialize(C applicationContext);
}
Callback interface for initializing a Spring ConfigurableApplicationContext prior to being refreshed.
该接口是整个spring容器在刷新之前初始化ConfigurableApplicationContext的回调接口，即在容器刷新之前会调用该类的initialize方法。
实现这个接口可以在整个spring容器还没被初始化之前搞事情。
举几个可能的例子：
- 利用这时候class还没被类加载器加载的时机，进行动态字节码注入
- 应用配置激活
扩展接口
package com.artisan.bootspringextend.testextends;
import lombok.extern.slf4j.Slf4j;
import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ConfigurableApplicationContext;
/**
* @author 小工匠
* @version 1.0
* @date 2022/11/26 22:16
* @mark: show me the code , change the world
*/
@Slf4j
public class ExtendApplicationContextInitializer implements ApplicationContextInitializer {
@Override
public void initialize(ConfigurableApplicationContext applicationContext) {
log.info("ExtendApplicationContextInitializer # initialize Called");
}
}
扩展生效方式
方式一 ： Spring SPI扩展
在spring.factories中加入
org.springframework.context.ApplicationContextInitializer=com.artisan.bootspringextend.testextends.ExtendApplicationContextInitializer
方式二 ： 配置文件
context.initializer.classes=com.artisan.bootspringextend.testextends.ExtendApplicationContextInitializer
方式三 ：启动类手工add
调整一下启动方式
SpringApplication springApplication = new SpringApplication(BootSpringExtendApplication.class);
springApplication.addInitializers(new ExtendApplicationContextInitializer());
springApplication.run(args);测试结果
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.4.2)
2022-11-26 22:38:12.280 INFO 15048 --- [ main] .b.t.ExtendApplicationContextInitializer : ExtendApplicationContextInitializer # initialize Called
2022-11-26 22:38:12.305 INFO 15048 --- [ main] c.a.b.BootSpringExtendApplication : Starting BootSpringExtendApplication using Java 1.8.0_261 on LAPTOP-JF3RBRRJ with PID 15048 (D:\IdeaProjects\boot2\boot-spring-extend\target\classes started by artisan in D:\IdeaProjects\boot2)
2022-11-26 22:38:12.306 INFO 15048 --- [ main] c.a.b.BootSpringExtendApplication : No active profile set, falling back to default profiles: default
2022-11-26 22:38:12.723 INFO 15048 --- [ main] c.a.b.BootSpringExtendApplication : Started BootSpringExtendApplication in 0.777 seconds (JVM running for 1.916)
Process finished with exit code 0看
2022-11-26 22:38:12.280 INFO 15048 --- [ main] .b.t.ExtendApplicationContextInitializer : ExtendApplicationContextInitializer # initialize Called
