Spring的Java配置方式—@Configuration和@Bean实现Java配置

╰半橙微兮° 2023-08-17 16:00 123阅读 0赞

### **1、@Configuration 和 @Bean和@ComponentScan** ###

Spring的Java配置方式是通过 @Configuration 和 @Bean 和@ComponentScan注解实现的：  
**a、@Configuration 作用于类上，相当于一个xml配置文件**  
**b、@Bean 作用于方法上，相当于xml配置中的<bean>**

### **2、Java配置示例** ###

演示通过Java配置的方式进行Spring配置，并且实现Spring IOC功能。  
2.1) 创建工程以及导入依赖(Maven)

<dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot</artifactId>
            </dependency>

2.2）@Configuration

package conf;
    
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;
    
    @Configuration
    @ComponentScan(basePackages = "conf")
    public class BeanConfig {
    
        @Bean
        public User getUser(){
            return new User();
        }
    }

package conf;
    
    public class User {
    
        private String name = "Jack";
        private String gender = "male";
        private Integer age = 12;
    
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public String getGender() {
            return gender;
        }
    
        public void setGender(String gender) {
            this.gender = gender;
        }
    
        public Integer getAge() {
            return age;
        }
    
        public void setAge(Integer age) {
            this.age = age;
        }
    
        @Override
        public String toString() {
            return "User{" +
                    "name='" + name + '\'' +
                    ", gender='" + gender + '\'' +
                    ", age=" + age +
                    '}';
        }
    }

2.3)注解Bean

package conf;
    
    import org.springframework.stereotype.Component;
    
    @Component
    public class Customer {
    
        private String custName = "Ross";
        private String custGender = "female";
        private Integer custAge = 17;
    
        public String getCustName() {
            return custName;
        }
    
        public void setCustName(String custName) {
            this.custName = custName;
        }
    
        public String getCustGender() {
            return custGender;
        }
    
        public void setCustGender(String custGender) {
            this.custGender = custGender;
        }
    
        public Integer getCustAge() {
            return custAge;
        }
    
        public void setCustAge(Integer custAge) {
            this.custAge = custAge;
        }
    
        @Override
        public String toString() {
            return "Customer{" +
                    "custName='" + custName + '\'' +
                    ", custGender='" + custGender + '\'' +
                    ", custAge=" + custAge +
                    '}';
        }
    }

2.4）获取bean

package conf;
    
    import org.springframework.context.annotation.AnnotationConfigApplicationContext;
    
    public class GetBeanTest {
    
    
        public static void main(String[] args) {
            // 通过Java配置来实例化Spring容器
            AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(BeanConfig.class);
    
            // 在Spring容器中获取Bean对象
            User user = context.getBean(User.class);
            System.out.println(user.toString());
    
            // 通过Java配置来实例化Spring容器
    
            // 在Spring容器中获取Bean对象
            Customer customer = context.getBean(Customer.class);
            System.out.println(customer.toString());
    
            // 销毁该容器
            context.destroy();
        }
    }

结果输出：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ppYWhhbzExODY_size_16_color_FFFFFF_t_70][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ppYWhhbzExODY_size_16_color_FFFFFF_t_70]: /images/20230810/75c46c20a07541cb943e58e0f87f6a49.png