10. 注解开发Bean作用范围和生命周期管理

news2024/11/24 4:50:42

1. bean作用范围注解配置

使用@Scope注解定义bean作用范围

1.1. singleton为单例

1.1.1 在bean头上使用@Scope注解，singleton

package com.lin.dao.impl;

import com.lin.dao.BookDao;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Repository;

@Repository
@Scope("singleton")
public class BookDaoImpl implements BookDao {

    public void save() {
        System.out.println("dao的save");
    }
}

1.1.2 测试类创建容器获取俩个bean打印

package com.lin.app;

import com.lin.config.SpringConfig;
import com.lin.dao.BookDao;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class App {
    public static void main(String[] args) {

        //1.创建spring容器,加载配置配置类
        AnnotationConfigApplicationContext springContext = new AnnotationConfigApplicationContext(SpringConfig.class);
        //2.根据类型获取bean
        BookDao bookDao1 = springContext.getBean(BookDao.class);
        BookDao bookDao2 = springContext.getBean(BookDao.class);
      
        System.out.println(bookDao1);
        System.out.println(bookDao2);


    }
}

1.1.3运行结果

1.2 prototype，非单例

1.2.1 在bean头上使用@Scope注解，prototype

package com.lin.dao.impl;

import com.lin.dao.BookDao;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Repository;

@Repository
@Scope("prototype")
public class BookDaoImpl implements BookDao {

    public void save() {
        System.out.println("dao的save");
    }
}

1.2.2 测试类创建容器依旧获取俩个bean打印

package com.lin.app;

import com.lin.config.SpringConfig;
import com.lin.dao.BookDao;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class App {
    public static void main(String[] args) {

        //1.创建spring容器,加载配置配置类
        AnnotationConfigApplicationContext springContext = new AnnotationConfigApplicationContext(SpringConfig.class);
        //2.根据类型获取bean
        BookDao bookDao1 = springContext.getBean(BookDao.class);
        BookDao bookDao2 = springContext.getBean(BookDao.class);
      
        System.out.println(bookDao1);
        System.out.println(bookDao2);

    }
}

1.2.3 运行结果观察

2. bean生命周期注解配置

2.1@PostConstruct、@PreDestroy定义bean生命周期

在bean中定义一个init方法，destroy，在该方法上使用该@PostConstruct、@PreDestroy注解；

package com.lin.dao.impl;

import com.lin.dao.BookDao;
import org.springframework.stereotype.Repository;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;

@Repository

public class BookDaoImpl implements BookDao {

    public void save() {
        System.out.println("dao的save");
    }

    public BookDaoImpl() {
        System.out.println("Construct");
    }

    @PostConstruct
    public void init(){
        System.out.println("init...");
    }

    @PreDestroy
    public void destroy(){
        System.out.println("destroy...");
    }
}

2.2 在测试类中创建容器，并注册关闭钩子或者直接关闭容器,运行

package com.lin.app;

import com.lin.config.SpringConfig;
import com.lin.dao.BookDao;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class App {
    public static void main(String[] args) {

        //1.创建spring容器,加载配置配置类
        AnnotationConfigApplicationContext springContext = new            AnnotationConfigApplicationContext(SpringConfig.class);
        springContext.registerShutdownHook();
    }
}