👍自动装配方式

• IoC容器根据bean所依赖的资源在容器中自动查找并注入到bean中的过程称为自动装配

• 自动装配方式

  • 按类型（常用)
  • 按名称
  • 按构造方法
  • 不启用自动装配

👍案例

👍BookDao接口

package com.study.dao;
public interface BookDao {
    void save();
}

👍BookDaoImpl实现类

package com.study.dao.impl;

import com.study.dao.BookDao;

public class BookDaoImpl implements BookDao {
    public void save() {
        System.out.println("BookDaoImpl...");
    }
}

👍BookService接口

package com.study.service;

public interface BookService {
    void save();
}

👍BookServiceImpl实现类

package com.study.service.impl;

import com.study.dao.BookDao;
import com.study.service.BookService;

public class BookServiceImpl implements BookService {

    private BookDao bookDao;


    public void save() {
        bookDao.save();

        System.out.println("BookServiceImpl...");
    }

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

👍applicationContext.xml配置文件

注意：

• 第一种按类型autowire="byType"，id="bookDao" 则可以不写
• 第二种按名称autowire="byName"，如果id="bookDao1"，则报错

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="bookDao" class="com.study.dao.impl.BookDaoImpl"></bean>
    <bean id="bookService" class="com.study.service.impl.BookServiceImpl" autowire="byType">
    </bean>
   <!-- 第一种按类型autowire="byType"，id="bookDao" 则可以不写-->
   <!-- 第二种按名称autowire="byName"，如果id="bookDao1"，则报错-->


</beans>

👍Test测试类

import com.study.dao.BookDao;
import com.study.service.BookService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {
    public static void main(String[] args) {
        ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        BookService service = app.getBean(BookService.class);
        service.save();
    }
}
/*
BookDaoImpl...
BookServiceImpl...
 */