注解开发定义bean

不指定名称

package org.example.service.impl;

import org.example.dao.BookDao;
import org.example.service.BookService;
import org.springframework.stereotype.Component;

@Component
public class BookServiceimpl implements BookService {
    private BookDao bookDao;

    public void setBookDao(BookDao bookDao) {
        this.bookDao = bookDao;
    }

    public void save() {
        System.out.println("book service save");
        bookDao.save();
    }
}

指定名称

package org.example.dao.impl;

import org.example.dao.BookDao;
import org.springframework.stereotype.Component;

@Component("bookDao")
public class BookDaoimpl implements BookDao {
    @Override
    public void save() {
        System.out.println("book dao save");
    }
}

xml文件

<?xml version="1.0" encoding="UTF-8"?>
<!--        开启context命名空间-->
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="
       http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd">
    <context:component-scan base-package="org.example.dao.impl"/>
    <context:component-scan base-package="org.example.service.impl"/>
</beans>

package org.example;

import org.example.dao.BookDao;
import org.example.service.BookService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;

public class AppForDIAtuoware {
    public static void main(String[] args) {
        ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        BookDao bookDao = (BookDao) ctx.getBean("bookDao");
        bookDao.save();
        BookService bookService=ctx.getBean(BookService.class);
        System.out.println(bookService);
    }
}