SpringBoot–application.yml的数据类型对应

简介

本文介绍SpringBoot的配置文件与Java转换时数据类型的对应关系。

引用

spring:
  application:
    name: storage
  cloud:
    config:
      name: ${spring.application.name}

数组

法1：逗号

applicaiton.yml

单行写法

test:
  myList: Tony,Pepper

多行写法

test:
  myList: "
    Tony,
    Peter
  "

代码

@Value("${test.myList}")
private List<String> lastNames;

 或者：

@Value("#{'${test.myList}'.split(',')}")
private List<String> lastNames;

注意：以上List<String> 完全可以换成String[]、Set<String>。

取到的结果都是下边这个（自动以,分割，并去除空白字符）：

[
  "Tony",
  "Peter"
]

法2：并列的“-” 

applicaiton.yml

test:
  myList:
    - Tony
    - Pepper

代码（成功的）

package com.example.tmp;

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

import javax.annotation.PostConstruct;
import java.util.List;

@Data
@Component
@ConfigurationProperties(prefix = "test")
public class TestProperties {
    private List<String> mylist;

    @PostConstruct
    public void print() {
        System.out.println(mylist);
    }
}

运行结果

[Tony, Pepper]

代码（失败的）

package com.example.tmp;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import java.util.List;

@Component
public class TestConfig {
    @Value("${test.mylist}")
    private List<String> mylist;

    @PostConstruct
    public void print() {
        System.out.println(mylist);
    }
}

这样启动会直接报错：

Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder ‘test.mylist’ in value “${test.mylist}” 

Map

法1：对象

application.yml

test:
  myMap:
    lastName: Tony
    firstName: Stark

代码

package com.example.tmp;

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

import javax.annotation.PostConstruct;
import java.util.Map;

@Data
@Component
@ConfigurationProperties(prefix = "test")
public class TestProperties {
    private Map<String, String> myMap;

    @PostConstruct
    public void print() {
        System.out.println(myMap);
    }
}

执行结果

{lastName=Tony, firstName=Stark}

注意

 如果application.yml如下：

test:
  myMap:
    "19:00:00": 5
    "19:30:00": 6

打印结果为：

{190000=5, 193000=6}

暂时没找到原因，如果要用时间，可以用数组包含对象的方式：见下边“数组包含对象”

法2：对象放到字符串中

application.yml

test:
  myMap:
    '{
      lastName: "Tony",
      firstName: "Stark",
      code: "01"
    }'

代码 

@Value("#{${test.myMap}}")
Map<String, String> map;

注意

1. 对于01，外边必须有引号

否则识别出来之后，只有1，少了0

2. application.yml的对象必须放到引号里

下边几种方法都是不可以的：

test:
  myMap:
    lastName: "Tony",
    firstName: "Stark",
    code: 01

test:
  myMap:
    {
      lastName: "Tony",
      firstName: "Stark",
      code: 01
    }

3.key不能有横线，可以有下划线 。

比如：last-name不可以，last_name可以。

数组包含对象

application.yml

test:
  myMap:
    -
      time: "19:00:00"
      delay: 5
    -
      time: "19:30:00"
      delay: 6

或者 

test:
  myMap:
    - {time: "19:00:00", delay: 5}
    - {time: "19:30:00", delay: 6}

代码

package com.example.tmp;

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

import javax.annotation.PostConstruct;
import java.util.List;
import java.util.Map;

@Data
@Component
@ConfigurationProperties(prefix = "test")
public class MyBean {
    private List<Map<String, String>> myMap;

    @PostConstruct
    public void print() {
        System.out.println(myMap);
    }
}

执行结果

[{delay=5, time=19:00:00}, {time=19:30:00, delay=6}]

 或者这么写：

package com.example.tmp;

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

import javax.annotation.PostConstruct;
import java.util.List;

@Data
@Component
@ConfigurationProperties(prefix = "test")
public class MyBean {
    private List<Program> myMap;

    @PostConstruct
    public void print() {
        System.out.println(myMap);
    }
    @Data
    private static class Program{
        private String time;
        private Integer delay;
    }
}

结果

[MyBean.Program(time=19:00:00, delay=5), MyBean.Program(time=19:30:00, delay=6)]