一、@value注解

@Value("${key}") ， key 来自 application.properties(yml)

项目结构

#配置端口号
server.port=8082
#context-path
server.servlet.context-path=/myboot

#自定义key=value
school.name=清华大学
school.website=www.tsinghua.edu.cn
school.address=北京海淀区

site=www.baidu.com

package com.it.controller;

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 HelloController {

    @Value("${server.port}")
    private Integer port;
    @Value("${server.servlet.context-path}")
    private String contextPath;
    @Value("${school.name}")
    private String name;
    @Value("${site}")
    private String site;

    @RequestMapping(value = "/data")
    @ResponseBody
    public String queryData(){
        return name+",site="+site+",项目的访问地址="+contextPath+",使用的端口="+port;
    }

}

在 com.bjpowernode.springboot.config 包下创建 SchoolInfo 类，并为该 类加上Component 和 ConfigurationProperties 注解，prefix 可以不指定，如果不指定，那么 会去配置文件中寻找与该类的属性名一致的配置，prefix 的作用可以区分同名配置

1.SchoolInfo类

package com.it.entity;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

@Component
@ConfigurationProperties(prefix = "school")
public class SchoolInfo {
    private String name;

    private String website;

    private String address;

    @Override
    public String toString() {
        return "SchoolInfo{" +
                "name='" + name + '\'' +
                ", website='" + website + '\'' +
                ", address='" + address + '\'' +
                '}';
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getWebsite() {
        return website;
    }

    public void setWebsite(String website) {
        this.website = website;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }
}

2.controller包下的SchoolController类

package com.it.controller;

import com.it.entity.SchoolInfo;
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;

import javax.annotation.Resource;

@Controller
public class HelloController {
    
    @Resource
    private SchoolInfo info;
    
    
    @RequestMapping(value = "/info")
    @ResponseBody
    public String queryInfo(){
        return "SchoolInfo对象=="+info.toString();
    }

}

运行程序

?三、警告解决

在 SchoolInfo 类中使用了 ConfigurationProperties 注解，IDEA 会出现一个警告，不影响程序的执行 。

点击 open documentnation 跳转到网页，在网页中提示需要加一个依赖，我们将这个依赖拷贝，粘贴到 pom.xml 文件中 。