【java知识点】常用注解解析_java

1.@Order

@Order注解可应用于类、方法和字段属性上；
@Order注解定义了Spring IOC容器中Bean的执行顺序的优先级，而不是定义Bean的加载顺序，Bean的加载顺序不受@Order或Ordered接口的影响（个人理解：在项目启动的时候会将所有的bean进行注入，注入后我们调用所需要的bean的先后顺序不会受到这@Order注解的影响）。

简单的应用：

package com.example.practice.service.impl;

import com.example.practice.service.IUserService;
import org.springframework.stereotype.Service;

@Service
public class UserServiceImpl implements IUserService {


    @Override
    public void getUserInfo() {
        System.out.println("成功获取用户信息");
    }
}

package com.example.practice.service.impl;

import com.example.practice.service.ICarService;
import org.springframework.stereotype.Service;

@Service
public class CarServiceImpl implements ICarService {


    @Override
    public void getCarInfo() {
        System.out.println("成功获取车辆信息");
    }
}

package com.example.practice.anno;

import com.example.practice.service.impl.UserServiceImpl;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.annotation.Order;

@Configuration
@Order(1)
public class AConfig {

    @Bean
    public UserServiceImpl aUserService() {
        System.out.println("UserServiceImpl加载完成");
        return new UserServiceImpl();
    }

}

package com.example.practice.anno;

import com.example.practice.service.impl.CarServiceImpl;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.annotation.Order;

@Configuration
@Order(2)
public class BConfig {

    @Bean
    public CarServiceImpl aCarService() {
        System.out.println("CarServiceImpl加载完成");
        return new CarServiceImpl();
    }

}

测试方法：

package com.example.practice.MainTest;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Main {

    public static void main(String[] args) {
        AnnotationConfigApplicationContext context =
                new AnnotationConfigApplicationContext("com.example.practice.anno");
    }

}