springboot依赖注入的注解使用

原创

虾米大王 2024-09-30 12:25:55 ©著作权

文章标签 spring boot 后端 java spring 包名 文章分类 Python 后端开发

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package com.shrimpking.test1;

import org.springframework.stereotype.Component;
import org.springframework.stereotype.Controller;
import org.springframework.stereotype.Repository;
import org.springframework.stereotype.Service;


/**
 * Created by IntelliJ IDEA.
 *
 * @Author : Shrimpking
 * @create 2024/1/5 20:50
 */
@Service
//@Controller
//@Repository
//@Component
public class FunctionService
{
    public String sayHello(String word){
        return "Hello " + word + " !";
    }
}

使用@Service注解声明当前FunctionService类是Spring管理的一个Bean。其中，使用@Component、@Service、@Repository和@Controller是等效的，可根据需要选用。

package com.shrimpking.test1;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Controller;
import org.springframework.stereotype.Repository;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;

/**
 * Created by IntelliJ IDEA.
 *
 * @Author : Shrimpking
 * @create 2024/1/5 20:52
 */
@Service
//@Controller
//@Repository
//@Component
public class UseFunctionService
{
    @Autowired
    //@Resource
    private FunctionService functionService;

    public String sayHello(String word){
        return this.functionService.sayHello(word);
    }
}

使用@Autowired将FunctionService的实体Bean注入到UseFunctionService中，让UseFunctionService具备FunctionService的功能，此处使用JSR-330的@Inject注解或者JSR-250的@Resource注解是等效的。

package com.shrimpking.test1;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

/**
 * Created by IntelliJ IDEA.
 *
 * @Author : Shrimpking
 * @create 2024/1/5 20:56
 */
@Configuration
@ComponentScan("com.shrimpking.test1")
public class DiConfig
{
}

使用@ComponentScan，自动扫描包名下所有使用@Service、@Component、@Repository和@Controller的类，并注册为Bean。

package com.shrimpking.test1;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

/**
 * Created by IntelliJ IDEA.
 *
 * @Author : Shrimpking
 * @create 2024/1/5 20:58
 */
public class Main
{
    public static void main(String[] args)
    {
        AnnotationConfigApplicationContext context
                = new AnnotationConfigApplicationContext(DiConfig.class);
        UseFunctionService useFunctionService = context.getBean(UseFunctionService.class);
        System.out.println(useFunctionService.sayHello("world"));
        context.close();
    }
}

使用AnnotationConfigApplicationContext作为Spring容器，接受输入一个配置类作为参数；