spring中@Configuration的用法

绝地灬酷狼 2023-01-23 09:48 13阅读 0赞

## 背景 ##

spring需要xml文件作为IOC容器，也就是spring的容器，用来管理对象。在spring4之后，JavaConfig（spring的一个子项目）成为了一个spring的核心功能。

@Configuration

@Configuration 等价于xml文件中的标签，用来管理生成,即在容器中交bean，获取出来后，就是对象。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5NDYzMTc1_size_16_color_FFFFFF_t_70]

## 使用 ##

直接在类上使用@Configuration，说明这个类是配置类，即是IOC容器，用来创建bean,那么自然而然就会想到，@bean用来标记创建具体的bean,  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5NDYzMTc1_size_16_color_FFFFFF_t_70 1]

## 项目目录 ##

@Configuration
    public class MyConfg { 
        @Bean
        public Student getStudent(){ 
            return new Student();
        }
    }

package com.yang.dao;
    
    import java.util.List;
    import java.util.Map;
    import java.util.Properties;
    import java.util.Set;
    
    public class Student { 
        public String address;
        public  String[] books;
        public int age;
        private List<String> hobbys;
        private Map<String,String> card;
        private Set<String> games;
        private Properties pro;
    
        public String getAddress() { 
            return address;
        }
    
        public void setAddress(String address) { 
            this.address = address;
        }
    
        public String[] getBooks() { 
            return books;
        }
    
        public void setBooks(String[] books) { 
            this.books = books;
        }
    
        public int getAge() { 
            return age;
        }
    
        public void setAge(int age) { 
            this.age = age;
        }
    
        public List<String> getHobbys() { 
            return hobbys;
        }
    
        public void setHobbys(List<String> hobbys) { 
            this.hobbys = hobbys;
        }
    
        public Map<String, String> getCard() { 
            return card;
        }
    
        public void setCard(Map<String, String> card) { 
            this.card = card;
        }
    
        public Set<String> getGames() { 
            return games;
        }
    
        public void setGames(Set<String> games) { 
            this.games = games;
        }
    
        public Properties getPro() { 
            return pro;
        }
    
        public void setPro(Properties pro) { 
            this.pro = pro;
        }
    }

测试类：

import com.yang.confg.MyConfg;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.annotation.AnnotationConfigApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    public class Mytest { 
        public static void main(String[] args) { 
            //获取上下文
           // ApplicationContext conteWxt = new ClassPathXmlApplicationContext("auto.xml");
        ApplicationContext applicationContext = new AnnotationConfigApplicationContext(MyConfg.class);
            Object getStudent = applicationContext.getBean("getStudent");
            System.out.println(getStudent.toString());
        }
    }

## 易混点 ##

下面4个注解用来把类注册到容器中，即xml文件中（还需要xml文件作为容器）  
@Componet  
@Controller  
@Service  
@Reposity  
他们经常和<context:component-scans base-package=“org.yang.xxx”/>,//扫描包  
或者//表明可以使用注解  
一起用  
![在这里插入图片描述][20210714013557112.png]

![在这里插入图片描述][20210714013459819.png]

但@Configuration不需要xml文件，直接本身就是容器，可以生产bean。往往和@Bean一起用  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5NDYzMTc1_size_16_color_FFFFFF_t_70 2]  
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[20210714013557112.png]: /images/20221004/fe0c48a760c9427bbd7d0ffcaecf239a.png
[20210714013459819.png]: /images/20221004/718464b6caf5434e864ab2b6fe4edbef.png
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