SpringBoot 官方文档示例：(12)读取配置文件中属性的3种常用方式

一、SpringBoot读取配置文件里属性的几种方式：
1.通过定义配置类，使用
@Configuration注解和@ConfigurationProperties注解，然后注入该配置类，最后通过配置类的getter方法拿配置
2.通过@value注解
3.通过注入Enviroment bean

二、示例

1. application.properties

server.port=9070
username=amadeusliu
password=myPassword
school=tju

2.定义配置类：

package cn.edu.tju.config;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;

@ConfigurationProperties
@Configuration
public class MyConfig {
    public String username;
    public String password;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

3.controller中分别用各种方式获取配置属性

package cn.edu.tju.controller;

import cn.edu.tju.config.MyConfig;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.core.env.Environment;

@RestController
public class TestController {
    @Autowired
    Environment environment;
    @Autowired
    private MyConfig myConfig;
    @Value("${school}")
    private String school;

    public String getSchool() {
        return school;
    }

    public void setSchool(String school) {
        this.school = school;
    }

    @RequestMapping("getSchool")
    public String getInfo(){
        return getSchool();
    }

    @RequestMapping("getPassword")
    public String getPassword(){
        return myConfig.getPassword();
    }
    @RequestMapping("getVmInfo")
    public String getVmInfo(){
        return environment.getProperty("java.vm.info");
    }
}

4.启动程序，访问网址：

http://localhost:9070/getPassword
http://localhost:9070/getSchool
http://localhost:9070/getVmInfo

输出结果如下：