本篇文章继续上篇文章讲解Ioc基础，这篇文章主要介绍零配置实现ioc，现在相信大家项目中也基本都是没有了xml配置文件。废话不多说。一起学习

代码示例

• BookDao.java

package com.kevin.spring.demo1.dao;

/**

 * 图书数据访问接口

 */

public interface BookDao {

    /**

     * 添加图书

     *

     * @param bookName

     * @return

     */

    String addBook(String bookName);

}

• BookDaoImpl.java

/**

 * 接口实现类

 */

@Repository

public class BookDaoImpl implements BookDao {

    /**

     * 添加图书接口

     *

     * @param bookName

     * @return

     */

    public String addBook(String bookName) {

        return "添加图书《" + bookName + "》成功";

    }

}

• BookService.java

@Service

public class BookService {

    @Resource

    BookDaoImpl bookDao;

    public void storeBook(String bookName){

        String result = bookDao.addBook(bookName);

        System.out.println(result);

    }

}

• User.java

package com.kevin.spring.demo1.entity;

import org.springframework.stereotype.Component;

@Component

public class User {

    public User() {

        System.out.println("创建User对象");

    }

    public User(String msg) {

        System.out.println("创建User对象" + msg);

    }

    public void show() {

        System.out.println("一个学生对象！");

    }

}

• ApplicationConfig.java

package com.kevin.spring.demo1.config;

import com.kevin.spring.demo1.entity.User;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.ComponentScan;

import org.springframework.context.annotation.Configuration;

@Configuration

@ComponentScan(basePackages = "com.kevin.spring.demo1")

public class ApplicationConfig {

    @Bean

    public User getUser(){

        return new User("成功");

    }

}

测试类

    @org.junit.Test

    public void testBook(){

        ApplicationContext ctx = new AnnotationConfigApplicationContext(ApplicationConfig.class);

        BookService bookService = ctx.getBean(BookService.class);

        bookService.storeBook("周杰伦");

        User user = ctx.getBean("getUser",User.class);

        user.show();

    }

运行结果

创建User对象

创建User对象成功

添加图书《周杰伦》成功

一个学生对象！

@Configuration

@Configuration 相当于配置文件中的<beans/>

@ComponentScan

@ComponentScan相当于配置文件中的context:component-scan

@Bean

@Bean相当于<bean/>，只能注解在方法和注解上，一般在方法上使用

方法名相当于id

这里注意上面获取user时用的是getUser,因为方法名相当于id

@Value获取properties配置

• 新建一个dev.properties文件

boy.name = kevin

boy.age = 20

• BoyUtil.java

package com.kevin.spring.demo1.util;

import org.springframework.beans.factory.annotation.Value;

import org.springframework.context.annotation.PropertySource;

import org.springframework.stereotype.Component;

@Component

@PropertySource("classpath:dev.properties")

public class BoyUtil {

    @Value("${boy.name}")

    private String name;

    @Value("${boy.age}")

    private String age;

    @Override

    public String toString() {

        return "BoyUtil{" +

                "name='" + name + '\'' +

                ", age='" + age + '\'' +

                '}';

    }

	//get和set方法省略

}

测试

    @org.junit.Test

    public void testBoyUtil(){

        ApplicationContext ctx = new AnnotationConfigApplicationContext(ApplicationConfig.class);

        BoyUtil boyUtil = ctx.getBean(BoyUtil.class);

        System.out.println(boyUtil);

    }

输出结果

创建User对象

创建User对象成功

BoyUtil{name='kevin', age='20'}

好了，springIoc基础就暂时告一段落。玩的开心

代码：https://github.com/runzhenghengbin/spring-study

参考：https://www.cnblogs.com/best/p/5727935.html#_label3