一、新建properties文件
在resources目录下，新建一个 fy.properties 文件。

test.fy.name=best
test.fy.pwd=pwd123@

二、定义配置类
@Configuration
@PropertySource("classpath:fy.properties")
注意这里的配置路径

package com.springboot.springboot_web.config;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

@Configuration
@PropertySource("classpath:fy.properties")
public class FySettings {

    @Value("${test.fy.name}")
    private String name;
    @Value("${test.fy.pwd}")
    private String pwd;

    public String getName() {
        return name;
    }

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

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }
}

三、应用
注入一下
@Resource
FySettings fySettings;

package com.springboot.springboot_web.control;

import com.springboot.springboot_web.config.FySettings;
import com.springboot.springboot_web.model.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.annotation.Resource;
import java.util.Date;

@Controller
@RequestMapping("/fastjson")
public class FastjsonController {

    @Resource
    FySettings fySettings;

    @RequestMapping("/test")
    @ResponseBody
    public User testJson() {
        User user = new User();
        user.setId(1);
        user.setUsername(fySettings.getName());
        user.setPassword(fySettings.getPwd());
        user.setBirthday(new Date());
        return user;
    }
}

测试一下，访问路径 http://127.0.0.1:8081/fastjson/test

{
    "birthday": "2018-08-20 05:05:09",
    "id": 1,
    "password": "pwd123@",
    "username": "best"
}