Spring注解之@Value详解

package org.springframework.beans.factory.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Target({ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER, ElementType.ANNOTATION_TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Value {
    String value();
}

ymlname: only-yml
student:
  name: yml里的name
  age: 20
  tel : 666

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
@Controller
public class TestValueController {
    // 只在application.yml中配置
    @Value("${ymlname}")
    private String ymlname;
    // 只在application.properties中配置
    @Value("${propname}")
    private String propname;
    // application.yml和application.properties均有该配置
    @Value("${student.name}")
    private String name;
    // 配置文件中的字段名和属性名不一致
    @Value("${student.age}")
    private int nianling;
    // application.yml和application.properties均没有该配置，设置默认值
    @Value("${student.score:100}")
    private int score;
    // application.yml有该配置，同时设置默认值
    @Value("${student.tel:888}")
    public int tel;
    @ResponseBody
    @RequestMapping(value = "/test")
    public String testValue() {
        return "ymlname —— " + ymlname + "<br/>" +
                "propname —— " + propname + "<br/>" +
                "name —— " + name + "<br/>" +
                "nianling —— " + nianling + "<br/>" +
                "score —— " + score + "<br/>" +
                "tel —— " + tel;
    }
}

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class SpringbootTestApplication {
    @Value("${student.name}")
    public static String name;
    public static void main(String[] args) {
        SpringApplication.run(SpringbootTestApplication.class, args);
        System.out.println("name: " + name);
    }
}

    public static String name;
    @Value("${student.name}")
    public void setName(String param) {
    	name = param;
    }

import lombok.AllArgsConstructor;
import lombok.Data;
@Data
@AllArgsConstructor
public class User {
    private String name;
    private String password;
}

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class TestConfig {
    @Bean(name = "user")
    public User getUser() {
        return new User("zhangsan","66666");
    }
}

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import javax.annotation.PostConstruct;
@Slf4j
@Component
public class TestBeanPro {
    @Value("#{user.name}")
    private String userName;
    @PostConstruct
    public void init() {
        log.info("***************************** userName:{}.", userName);
    }
}