SpringBoot(3) Spring Boot属性配置文件详解

曾经终败给现在 2022-06-07 04:00 231阅读 0赞

感谢作者:[翟永超][Link 1] 原文链接:[http://blog.didispace.com/springbootproperties/][http_blog.didispace.com_springbootproperties]

相信很多人选择Spring Boot主要是考虑到它既能兼顾Spring的强大功能，还能实现快速开发的便捷。我们在Spring Boot使用过程中，最直观的感受就是没有了原来自己整合Spring应用时繁多的XML配置内容，替代它的是在`pom.xml`中引入模块化的`Starter POMs`，其中各个模块都有自己的默认配置，所以如果不是特殊应用场景，就只需要在`application.properties`中完成一些属性配置就能开启各模块的应用。

在之前的各篇文章中都有提及关于`application.properties`的使用，主要用来配置数据库连接、日志相关配置等。除了这些配置内容之外，本文将具体介绍一些在`application.properties`配置中的其他特性和使用方法。

## 自定义属性与加载 ##

我们在使用Spring Boot的时候，通常也需要定义一些自己使用的属性，我们可以如下方式直接定义：

然后通过`@Value("${属性名}")`注解来加载对应的配置属性，具体如下：

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     </div></pre> </td> 
   <td style="padding:10px 20px 10px 0px; margin:0px; border:none; outline:0px; font-style:inherit; font-family:inherit; font-size:16px; vertical-align:middle"> <pre style="overflow:auto; font-family:inherit; margin-top:0px; margin-bottom:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; vertical-align:baseline">
     
      
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      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(117,113,94)">@Component</span>
     
      
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      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:bold; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(249,38,114)">public</span> 
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline"><span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:bold; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(249,38,114)">class</span> <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:bold; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(255,255,255)">BlogProperties</span> </span>{
     
      
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     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em"></div>
     
      
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      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(117,113,94)">@Value</span>(
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(166,226,46)">"${com.didispace.blog.name}"</span>)
     
      
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      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:bold; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(249,38,114)">private</span> String name;
     
      
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      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(117,113,94)">@Value</span>(
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(166,226,46)">"${com.didispace.blog.title}"</span>)
     
      
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      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:bold; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(249,38,114)">private</span> String title;
     
      
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      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(117,113,94)">// 省略getter和setter</span>
     
      
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      }
     
      
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按照惯例，通过单元测试来验证BlogProperties中的属性是否已经根据配置文件加载了。

<table style="border-collapse:collapse; border-spacing:0px; margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; font-size:16px; vertical-align:middle; line-height:1.6em; width:auto"> 
 <tbody style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline"> 
  <tr style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline"> 
   <td style="padding:10px 0px; margin:0px; border:none; outline:0px; font-style:inherit; font-family:inherit; font-size:16px; vertical-align:middle"> <pre style="overflow:auto; font-family:inherit; margin-top:0px; margin-bottom:0px; padding:0px 20px 0px 0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; vertical-align:baseline; color:rgb(102,102,102); text-align:right">
     
      
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      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(117,113,94)">@RunWith</span>(SpringJUnit4ClassRunner.class)
     
      
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      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(117,113,94)">@SpringApplicationConfiguration</span>(Application.class)
     
      
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      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:bold; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(249,38,114)">public</span> 
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline"><span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:bold; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(249,38,114)">class</span> <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:bold; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(255,255,255)">ApplicationTests</span> </span>{
     
      
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      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(117,113,94)">@Autowired</span>
     
      
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      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:bold; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(249,38,114)">private</span> BlogProperties blogProperties;
     
      
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      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(117,113,94)">@Test</span>
     
      
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      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline"><span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:bold; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(249,38,114)">public</span> <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:bold; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(249,38,114)">void</span> <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:bold; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(166,226,46)">getHello</span><span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline">()</span> <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:bold; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(249,38,114)">throws</span> Exception </span>{
     
      
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      		Assert.assertEquals(blogProperties.getName(), 
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(166,226,46)">"程序猿DD"</span>);
     
      
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      		Assert.assertEquals(blogProperties.getTitle(), 
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(166,226,46)">"Spring Boot教程"</span>);
     
      
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     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      	}
     
      
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      }
     
      
     </div></pre> </td> 
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## 参数间的引用 ##

在`application.properties`中的各个参数之间也可以直接引用来使用，就像下面的设置：

`com.didispace.blog.desc`参数引用了上文中定义的`name`和`title`属性，最后该属性的值就是`程序猿DD正在努力写《Spring Boot教程》`。

## 使用随机数 ##

在一些情况下，有些参数我们需要希望它不是一个固定的值，比如密钥、服务端口等。Spring Boot的属性配置文件中可以通过`${random}`来产生int值、long值或者string字符串，来支持属性的随机值。

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     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      4
     
      
     </div>
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      5
     
      
     </div>
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      6
     
      
     </div>
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      7
     
      
     </div>
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      8
     
      
     </div>
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      9
     
      
     </div>
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      10
     
      
     </div></pre> </td> 
   <td style="padding:10px 20px 10px 0px; margin:0px; border:none; outline:0px; font-style:inherit; font-family:inherit; font-size:16px; vertical-align:middle"> <pre style="overflow:auto; font-family:inherit; margin-top:0px; margin-bottom:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; vertical-align:baseline">
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(117,113,94)"># 随机字符串</span>
     
      
     </div>
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      com.didispace.blog.value=
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(166,226,46)">${random.value}</span>
     
      
     </div>
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(117,113,94)"># 随机int</span>
     
      
     </div>
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      com.didispace.blog.number=
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(166,226,46)">${random.int}</span>
     
      
     </div>
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(117,113,94)"># 随机long</span>
     
      
     </div>
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      com.didispace.blog.bignumber=
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(166,226,46)">${random.long}</span>
     
      
     </div>
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(117,113,94)"># 10以内的随机数</span>
     
      
     </div>
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      com.didispace.blog.test1=
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(166,226,46)">${random.int(10)}</span>
     
      
     </div>
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(117,113,94)"># 10-20的随机数</span>
     
      
     </div>
     
      
     <div style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; height:1.6em">
      
       
      com.didispace.blog.test2=
      
       
      <span style="margin:0px; padding:0px; border:0px; outline:0px; font-weight:inherit; font-style:inherit; font-family:inherit; vertical-align:baseline; color:rgb(166,226,46)">${random.int[10,20]}</span>
     
      
     </div></pre> </td> 
  </tr> 
 </tbody> 
</table>

## 通过命令行设置属性值 ##

相信使用过一段时间Spring Boot的用户，一定知道这条命令：`java -jar xxx.jar --server.port=8888`，通过使用–server.port属性来设置xxx.jar应用的端口为8888。

在命令行运行时，连续的两个减号`--`就是对`application.properties`中的属性值进行赋值的标识。所以，`java -jar xxx.jar --server.port=8888`命令，等价于我们在`application.properties`中添加属性`server.port=8888`，该设置在样例工程中可见，读者可通过删除该值或使用命令行来设置该值来验证。

通过命令行来修改属性值固然提供了不错的便利性，但是通过命令行就能更改应用运行的参数，那岂不是很不安全？是的，所以Spring Boot也贴心的提供了屏蔽命令行访问属性的设置，只需要这句设置就能屏蔽：`SpringApplication.setAddCommandLineProperties(false)`。

## 多环境配置 ##

我们在开发Spring Boot应用时，通常同一套程序会被应用和安装到几个不同的环境，比如：开发、测试、生产等。其中每个环境的数据库地址、服务器端口等等配置都会不同，如果在为不同环境打包时都要频繁修改配置文件的话，那必将是个非常繁琐且容易发生错误的事。

对于多环境的配置，各种项目构建工具或是框架的基本思路是一致的，通过配置多份不同环境的配置文件，再通过打包命令指定需要打包的内容之后进行区分打包，Spring Boot也不例外，或者说更加简单。

在Spring Boot中多环境配置文件名需要满足`application-{profile}.properties`的格式，其中`{profile}`对应你的环境标识，比如：

*  `application-dev.properties`：开发环境
 *  `application-test.properties`：测试环境
 *  `application-prod.properties`：生产环境

至于哪个具体的配置文件会被加载，需要在`application.properties`文件中通过`spring.profiles.active`属性来设置，其值对应`{profile}`值。

如：`spring.profiles.active=test`就会加载`application-test.properties`配置文件内容

下面，以不同环境配置不同的服务端口为例，进行样例实验。

*  针对各环境新建不同的配置文件`application-dev.properties`、`application-test.properties`、`application-prod.properties`
 *  在这三个文件均都设置不同的`server.port`属性，如：dev环境设置为1111，test环境设置为2222，prod环境设置为3333
 *  application.properties中设置`spring.profiles.active=dev`，就是说默认以dev环境设置
 *  测试不同配置的加载
    
     *  执行`java -jar xxx.jar`，可以观察到服务端口被设置为`1111`，也就是默认的开发环境（dev）
     *  执行`java -jar xxx.jar --spring.profiles.active=test`，可以观察到服务端口被设置为`2222`，也就是测试环境的配置（test）
     *  执行`java -jar xxx.jar --spring.profiles.active=prod`，可以观察到服务端口被设置为`3333`，也就是生产环境的配置（prod）

按照上面的实验，可以如下总结多环境的配置思路：

*  `application.properties`中配置通用内容，并设置`spring.profiles.active=dev`，以开发环境为默认配置
 *  `application-{profile}.properties`中配置各个环境不同的内容
 *  通过命令行方式去激活不同环境的配置

注意:

1.注意编码问题，否则从配置文件中获取不到中文

2.java -jar命令的执行直接在jar所在的目录下即可

[Link 1]: http://blog.didispace.com/
[http_blog.didispace.com_springbootproperties]: http://blog.didispace.com/springbootproperties/