注解开发bean作用范围与生命周期管理

Bean管理

Bean作用范围

public class App 
{
    public static void main( String[] args )
    {
        ApplicationContext ctx = new AnnotationConfigApplicationContext(SpringConfig.class);
        BookDaoImpl bookDao1 = ctx.getBean(BookDaoImpl.class);
        BookDaoImpl bookDao2 = ctx.getBean(BookDaoImpl.class);
        System.out.println(bookDao1);
        System.out.println(bookDao2);
    }
}

打印出来俩个Bean是同一个对象(单例)

com.chentianyu.service.impl.BookDaoImpl@75f9eccc
com.chentianyu.service.impl.BookDaoImpl@75f9eccc

变成非单例对象(@Scope)

package com.chentianyu.Dao.impl;
import com.chentianyu.service.BookDao;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Repository;
@Repository
@Scope("prototype") //singleton:单例 ; prototype:非单例
public class BookDaoImpl implements BookDao {
}

com.chentianyu.Dao.impl.BookDaoImpl@75f9eccc
com.chentianyu.Dao.impl.BookDaoImpl@52aa2946

Bean生命周期

自定义的生命周期名称叫什么都可以

@Repository
@Scope("singleton") //singleton:单例 ; prototype:非单例
public class BookDaoImpl implements BookDao {
    public void save(){
        System.out.println("book dao save...");
    }
    @PostConstruct //构造方法后
    public void init(){
        System.out.println("book dao init...");
    }
    @PreDestroy //在彻底销毁之前
    public void destroy(){
        System.out.println("book dao destroy...");
    }
}

输出的是

book dao init...
com.chentianyu.service.impl.BookDaoImpl@568bf312
com.chentianyu.service.impl.BookDaoImpl@568bf312

要进行销毁的方式(一种就是关闭容器的方式来做)

public class App 
{
    public static void main( String[] args )
    {
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(SpringConfig.class);
        BookDaoImpl bookDao1 = ctx.getBean(BookDaoImpl.class);
        BookDaoImpl bookDao2 = ctx.getBean(BookDaoImpl.class);
        System.out.println(bookDao1);
        System.out.println(bookDao2);
        ctx.close();
    }
}

book dao init...
com.chentianyu.Dao.impl.BookDaoImpl@568bf312
com.chentianyu.Dao.impl.BookDaoImpl@568bf312
book dao destroy...

总结

• bean作用范围
  • @Scope
• bean的生命周期
  • @PostConstruct (构造方法后)
  • @PreDestroy (销毁前)