@PostConstruct注解
@PostConstruct注解好多人以为是Spring提供的。其实是Java自己的注解。
Java中该注解的说明:@PostConstruct该注解被用来修饰一个非静态的void()方法。被@PostConstruct修饰的方法会在服务器加载Servlet的时候运行,并且只会被服务器执行一次。PostConstruct在构造函数之后执行,init()方法之前执行。
通常我们会是在Spring框架中使用到@PostConstruct注解 该注解的方法在整个Bean初始化中的执行顺序:
Constructor(构造方法) -> @Autowired(依赖注入) -> @PostConstruct(注释的方法)
@Configuration public class BeanConfiguration { @Bean public ToyFactory toyFactory() { return new DefaultToyFactory(); } }
接口
public interface ToyFactory { Toy createToy(); }
接口实现类
package com.sixinshuier.Initialization.servive.impl; import com.sixinshuier.Initialization.entity.Toy; import com.sixinshuier.Initialization.servive.ToyFactory; import javax.annotation.PostConstruct; public class DefaultToyFactory implements ToyFactory { public DefaultToyFactory() { System.out.println("构造器..."); } // 1. 基于 @PostConstruct 注解 @PostConstruct public void init() { System.out.println("@PostConstruct : DefaultToyFactory 初始化中..."); } @Override public Toy createToy() { Toy toy = new Toy(); toy.setName("Football"); toy.setSize("big"); return toy; } }
main
package com.sixinshuier.Initialization.main; import com.sixinshuier.Initialization.config.BeanConfiguration; import com.sixinshuier.Initialization.entity.Toy; import com.sixinshuier.Initialization.servive.ToyFactory; import org.springframework.context.annotation.AnnotationConfigApplicationContext; public class PostConstructTest { public static void main(String[] args) { // 创建BeanFactory AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(); // 注册Configuration Class(配置类) applicationContext.register(BeanConfiguration.class); // 启动spring应用上下文 applicationContext.refresh(); // 依赖查找 ToyFactory toyFactory = applicationContext.getBean(ToyFactory.class); Toy toy = toyFactory.createToy(); System.out.println("ToyName:" + toy.getName() + " ToySize:" + toy.getSize()); //关闭Spring应用上下文 applicationContext.close(); } }
输出结果
构造器...
@PostConstruct : DefaultToyFactory 初始化中...
ToyName:Football ToySize:big
参考:https://blog.csdn.net/qq360694660/article/details/82877222