springboot 属性注入（@Autowired、@Resource）

迷南。 2023-02-22 15:53 4阅读 0赞

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### springboot 属性注入（@Autowired、@Resource） ###

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**相关注解**

**@Autowired：spring提供注解，根据类型注入属性**

@Target({ElementType.CONSTRUCTOR, ElementType.METHOD, ElementType.PARAMETER, ElementType.FIELD, ElementType.ANNOTATION_TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    public @interface Autowired {
    
    	/**
    	 * Declares whether the annotated dependency is required.
    	 * <p>Defaults to {@code true}.
    	 */
    	boolean required() default true;
    
    }

**@Qualifier：@Autowired注入时，若有多个同类型的bean，可使用该注解指定加载的bean的名称**

@Target({ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER, ElementType.TYPE, ElementType.ANNOTATION_TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    @Inherited
    @Documented
    public @interface Qualifier {
    
    	String value() default "";
    
    }

**@Resource：java提供注解，可根据名称（默认）、类型注入属性**

@Target({ElementType.TYPE, ElementType.FIELD, ElementType.METHOD})
    @Retention(RetentionPolicy.RUNTIME)
    @Repeatable(Resources.class)
    public @interface Resource {
    
        String name() default "";              //根据名称注入属性，默认使用名称注入
        Class<?> type() default Object.class;  //根据类型注入属性
    
    
        String lookup() default "";
        boolean shareable() default true;
        String mappedName() default "";
        String description() default "";
    
        Resource.AuthenticationType authenticationType() default Resource.AuthenticationType.CONTAINER;
    
        public static enum AuthenticationType {
            CONTAINER,
            APPLICATION;
    
            private AuthenticationType() {
            }
        }
    }

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**示例**

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**pojo 层**

**Person**

@Data
    public class Person {
    
        private String name;
        private Integer age;
    }

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**config 层**

**WebConfig**

@Configuration
    public class WebConfig {
    
        @Bean("person")
        public Person initPerson(){
            Person person=new Person();
            person.setName("瓜田李下");
            person.setAge(20);
    
            return person;
        }
    
        @Bean("person2")
        public Person initPerson2(){
            Person person=new Person();
            person.setName("瓜田李下 2");
            person.setAge(21);
    
            return person;
        }
    }

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**controller 层**

**HelloController**

@RestController
    public class HelloController {
    
        @Autowired
        @Qualifier("person")
        private Person person;
    
        @Autowired
        @Qualifier("person2")
        private Person person2;
    
        @RequestMapping("/hello")
        public String hello(){
            System.out.println("helloController：  "+person);
            System.out.println("helloController：  "+person2);
    
            return "success";
        }
    }

**Hello2Controller**

@RestController
    public class Hello2Controller {
    
        @Resource
        private Person person;
    
        @Resource
        private Person person2;
    
        @Resource(name = "person2")
        private Person person3;
    
        @RequestMapping("/hello2")
        public String hello(){
            System.out.println("hello2Controller：  "+person);
            System.out.println("hello2Controller：  "+person2);
            System.out.println("hello2Controller：  "+person3);
    
            return "success";
        }
    }

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**控制台输出**

**localhost:8080/hello**

helloController：  Person(name=瓜田李下, age=20)
    helloController：  Person(name=瓜田李下 2, age=21)

**localhost:8080/hello2**

hello2Controller：  Person(name=瓜田李下, age=20)
    hello2Controller：  Person(name=瓜田李下 2, age=21)
    hello2Controller：  Person(name=瓜田李下 2, age=21)