@Target({ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER, ElementType.ANNOTATION_TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Value {
  
    String value();
}

@Value("liqb")
private String name; // 注入普通字符串

@Value("#{systemProperties['os.name']}")
private String systemPropertiesName; // 注入操作系統(tǒng)屬性

@Value("#{ T(java.lang.Math).random() * 100.0 }")
private double randomNumber; //注入SpEL表達(dá)式結(jié)果

@Value("#{person.name}")
private String username; // 注入其他bean中屬性的值，即注入person對(duì)象的name屬性中的值

@Value("classpath:/config.properties")
private Resource resourceFile; // 注入文件資源

@Value("http://www.baidu.com")
private Resource url; // 注入U(xiǎn)RL資源

person.nickName=liqb

package com.tianxia.springannotation.config;

import com.tianxia.springannotation.entity.Person;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

/**
 * 配置類
 * @author liqb
 * @date 2023-05-04 11:28
 **/
@Configuration
@PropertySource(value={"classpath:/person.properties"})
public class MainConfigOfPropertyValues {

    @Bean
    public Person person() {
        return new Person();
    }
}

package com.tianxia.springannotation.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.springframework.beans.factory.annotation.Value;

import java.io.Serializable;

/**
 * Person類
 * @author liqb
 * @date 2023-04-21 16:00
 **/
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Person implements Serializable {

    /**
     * 姓名
     */
    private String name;

    /**
     * 年齡
     */
    private Integer age;

    /**
     * 昵稱
     */
    @Value("${person.nickName}")
    private String nickName;

    public Person(String name, Integer age) {
        this.name = name;
        this.age = age;
    }
}

server.name=server1,server2,server3
author.name=liqb

package com.tianxia.springannotation.config;

import com.tianxia.springannotation.entity.Person;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

/**
 * 配置類
 * @author liqb
 * @date 2023-05-04 11:28
 **/
@Configuration
@PropertySource(value={"classpath:/person.properties"})
public class MainConfigOfPropertyValues {

    @Bean
    public Person person() {
        return new Person();
    }
}

@Value("${author.name:liqb}")
private String name;

// SpEL：調(diào)用字符串Hello World的concat方法
@Value("#{'Hello World'.concat('!')}")
private String helloWorld;

// SpEL：調(diào)用字符串的getBytes方法，然后再調(diào)用其length屬性
@Value("#{'Hello World'.bytes.length}")
private String helloWorldBytes;

// SpEL：傳入一個(gè)字符串，根據(jù)","切分后插入列表中， #{}和${}配合使用時(shí)，注意不能反過來${}在外面，而#{}在里面
@Value("#{'${server.name}'.split(',')}")
private List<String> severs;