Spring Boot 2.X 装载 yaml 配置文件的键值对

谁借莪１个温暖的怀抱￠ 2024-04-20 09:25 0阅读 0赞

# 加载 yaml 配置文件 #

目前主要有3种方案

1.  @Value

*  适用于简单类型的注入（不支持复杂类型封装注解）
 *  只能一个个指定
 *  支持 SpringEl 语法

1.  @ConfigurationProperties(prefix = “A.B.C”)

*  可以根据变量名批量注入
 *  且只需要指定一个前缀，就能绑定有这个前缀的所有属性值
 *  不支持 SpringEl 语法
 *  支持JSR303进行配置文件值及校验

1.  Environment

*  仅支持 boolean、int、string 和 list 的行内写法，功能比 @Value 还弱

# 指定配置文件路径 #

PropertySource 指定路径，对于当前 Spring Boot 2.X 版本而言，默认仅能支持 \*.properties，还不支持 \*.yml 文件，因此我们需要修改默认的构造工厂，那么先来看看默认的构造工厂是怎么实现的。

## 源码解读 ##

### PropertySource ###

public @interface PropertySource {
 /** 
 	 * 加载资源的别名，如果不设置的话会从资源路径中提取文件名
 	 */
 String name() default "";
 
 /** 
 * 加载资源的路径，可使用classpath,如: "classpath:/config/test.yml"
 * 如果有多个文件路径放在{}中，使用','号隔开，如：{"classpath:/config/test1.yml","classpath:/config/test2.yml"}
 * 除使用classpath外,还可使用文件的地址,如："file:/rest/application.properties"
 	 * 当然不加前缀也是可以的
 */
 String[] value();
 /** 
 	 * 资源路径找不到文件后是否报错
 	 */
 boolean ignoreResourceNotFound() default false;
 
 /** 
 	 * 配置文件编码，一般设为 utf-8 
 	 */
 String encoding() default "";
 
 /**
 * 读取资源文件的工厂类
 */
 Class<? extends PropertySourceFactory> factory() default PropertySourceFactory.class;
 }

### DefaultPropertySourceFactory ###

public class DefaultPropertySourceFactory implements PropertySourceFactory {
 public DefaultPropertySourceFactory() {
 }
 	/*
 	* 如果显示指定了name，则用该名字创建 ResourcePropertySource，否则不用
 	* EncodedResource是对Resource的简单包装，增加了具体编码的属性
 	*/
 public PropertySource<?> createPropertySource(@Nullable String name, EncodedResource resource) throws IOException {
 return name != null ? new ResourcePropertySource(name, resource) : new ResourcePropertySource(resource);
 }
 }

### ResourcePropertySource ###

public class ResourcePropertySource extends PropertiesPropertySource {
    	/*
    	* 资源的原始名字（父类中的name，表示资源的别名）
    	*/
    	private final String resourceName;
    	……
    	/**
    	* 当有指定别名的时候，需要记录原始名 
    	*/
    	public ResourcePropertySource(String name, EncodedResource resource) throws IOException {
    		super(name, PropertiesLoaderUtils.loadProperties(resource));
    		this.resourceName = getNameForResource(resource.getResource());
    	}
    
    	/**
    	* 如果资源没有别名，则不用另外记录
    	*/
    	public ResourcePropertySource(EncodedResource resource) throws IOException {
    		super(getNameForResource(resource.getResource()), PropertiesLoaderUtils.loadProperties(resource));
    		this.resourceName = null;
    	}
    	
    	/**
    	* 获取资源时，同时查询原始名和别名
    	*/
    	public ResourcePropertySource withName(String name) {
    		if (this.name.equals(name)) {
    			return this;
    		}
    		// Store the original resource name if necessary...
    		if (this.resourceName != null) {
    			if (this.resourceName.equals(name)) {
    				return new ResourcePropertySource(this.resourceName, null, this.source);
    			}
    			else {
    				return new ResourcePropertySource(name, this.resourceName, this.source);
    			}
    		}
    		else {
    			// Current name is resource name -> preserve it in the extra field...
    			return new ResourcePropertySource(name, this.name, this.source);
    		}
    	}
    	……
    }

## Yaml 构造工厂 ##

由于默认的 DefaultPropertySourceFactory 仅支持 \*.properties 后缀的文件，因此需要对 Yaml 自定义一个构造工厂，继承于默认的属性构造工厂（DefaultPropertySourceFactory ）。

有两种方式可以通过 EncodedResource 资源加载 yaml

*  YamlPropertySourceLoader

private PropertySource<?> loadYaml(String name, EncodedResource resource) throws IOException {
 	Resource res = resource.getResource();
 	String sourceName = name != null ? name : res.getFilename();
 	//注意这里的name不能为空，因为其中的源码包含了，Assert.hasText(name, "Property source name must contain at least one character");
 	List<PropertySource<?>> sources = new YamlPropertySourceLoader().load(res.getFilename(), res);
 	return sources.get(0);
 }

*  YamlPropertiesFactoryBean

private PropertySource<?> loadYaml(String name, EncodedResource resource) {
 	YamlPropertiesFactoryBean factory = new YamlPropertiesFactoryBean();
 	factory.setResources(resource.getResource());
 	factory.afterPropertiesSet();
 	Properties properties = factory.getObject();
 	String sourceName = name != null ? name : resource.getResource().getFilename();
 	//注意这里的name不能为空，因为其中的源码包含了，Assert.hasText(name, "Property source name must contain at least one character");
 	return new PropertiesPropertySource(sourceName, properties);
 }

## 同时支持 properties 和 yaml 的混合工厂 ##

通过判断后缀，如果是 \*.yaml 或者 \*.yml 则通过上面方案构造，否则通过默认的工厂构造

public class MixPropertySourceFactory extends DefaultPropertySourceFactory {
 
 	@Override
 	public PropertySource<?> createPropertySource(String name, EncodedResource resource) throws IOException {
 		if(resource == null) return super.createPropertySource(name, resource);
 		Resource res = resource.getResource();
 		String sourceName = name != null ? name : res.getFilename();
 		if (!resource.getResource().exists()) {
 			return new PropertiesPropertySource(null, new Properties());
 	 } else if(sourceName.endsWith(".yml") || sourceName.endsWith(".yaml")) {
 	 	return loadYaml_1(name, resource);
 	 	//return loadYaml_2(name, resource);
 		} else {
 			return super.createPropertySource(name, resource);
 		}
 	}
 	
 	private PropertySource<?> loadYaml_1(String name, EncodedResource resource) throws IOException {
 		Resource res = resource.getResource();
 		String sourceName = name != null ? name : res.getFilename();
 		//注意这里的name不能为空，因为其中的源码包含了，Assert.hasText(name, "Property source name must contain at least one character");
 		List<PropertySource<?>> sources = new YamlPropertySourceLoader().load(res.getFilename(), res);
 		return sources.get(0);
 	}
 	
 	private PropertySource<?> loadYaml_2(String name, EncodedResource resource) {
 		YamlPropertiesFactoryBean factory = new YamlPropertiesFactoryBean();
 		factory.setResources(resource.getResource());
 		factory.afterPropertiesSet();
 		Properties properties = factory.getObject();
 		String sourceName = name != null ? name : resource.getResource().getFilename();
 		//注意这里的name不能为空，因为其中的源码包含了，Assert.hasText(name, "Property source name must contain at least one character");
 		return new PropertiesPropertySource(sourceName, properties);
 	}
 }

# 创建测试用的 yaml 文件 #

在 resources 目录下，创建 config 文件夹，然后新建一个 bob.yml 文件，添加上如下测试文本。

井号（ \# ）表示单行注释

接下来，我们要对如下类型分别进行测试

* `int`
 * `boolean`
 * `String`
 * `String[]`
 * `List<String>`
 * `Set<String>`
 * `Map<String, String>`
 * `List<Map<String, String>>`

引号的区别

*  不加引号，**等同于单引号**。
 *  单引号，会对转义字符进行转义，从而使得转义字符失去转义效果，字符串**原样输出**。
 *  双引号，转义字符会被解释为其应有的含义。

大小写、横杠、下划线  
yaml 文件对大小写不敏感，在 java 注解中横杠和下划线写不写都可以读出数据  
![在这里插入图片描述][2019092310555946.png]

person:
 bob:
 age: 26
 male: true
 company: tencentQQ
 
 pet1: #array
 - rabbit
 - tortoise
 - carp
 - tortoise
 pet2: #list
 - rabbit
 - tortoise
 - carp
 - tortoise
 pet3: #set
 - rabbit
 - tortoise
 - carp
 - tortoise
 plant: rose,lily,sunflower,pear,lily #list 行内写法
 languageEL: #使用StringEL表达式将字符串切分成数组
 "java,C#,python" 
 
 friend: {teacher: 'Jane', musician: 'F.I.R', scientist: 'Einstein'}
 friendEL: #使用StringEL表达式获取map
 "{teacher: 'Jane', musician: 'F.I.R', scientist: 'Einstein'}"
 family: #map
 father: Trump
 mother: Tina 
 brother: Tom
 
 play-game: #list<map>
 - name: GBA
 years: 5
 - name: Srike of Kings
 years: 3
 - name: Dragon Nest
 years: 2
 
 quote-1: 'a man\tof\nmany\ntalents, his age is ${age} and his company is ${person.bob.company}'
 quote-2: "a tman\tof\nmany\ntalents, his age is ${age} and his company is ${person.bob.company}"

# 使用 @Value 逐个注入属性 #

创建一个控制类，当访问指定网页时，将变量打印出来。

访问时注意大小写，且不能加后缀。比如，这里配置的 @GetMapping("/testValue")，那么就只能通过 `localhost:8080/testValue` 来访问

@Value 注解不用指定配置文件位置，就可以自动装配。

## 代码 ##

@RestController
 public class TestController {
 	
 	@Value("${person.bob.age}")
 	private int age;
 	@Value("${person.bob.male}")
 	private boolean male;
 	@Value("${person.bob.company}")
 	private String company;
 	
 //	@Value("${person.bob.pet1}")
 	private String[] pet1;
 //	@Value("${person.bob.pet2}")
 	private List<String> pet2;
 //	@Value("${person.bob.pet3}")
 	private Set<String> pet3;
 	@Value("${person.bob.plant}")
 	private List<String> plant;
 	@Value("#{'${person.bob.languageEL}'.split(',')}")
 	private List<String> languageEL;
 	
 //	@Value("${person.bob.friend}")
 	private Map<String, String> friend;
 	@Value("#{${person.bob.friendEL}}")
 	private Map<String, String> friendEL;
 //	@Value("#{${person.bob.family}}")
 	private Map<String, String> family;
 //	@Value("#{${person.bob.play-game}}")
 	public List<Map<String, String>> playgame;
 	
 	@Value("${person.bob.quote-0}")
 	private String quote0;
 	@Value("${person.bob.quote-1}")
 	private String quote1;
 	@Value("${person.bob.quote-2}")
 	private String quote2;
 	
 	@GetMapping("/testValue")
 	public YamlConfig testValue() {
 		YamlConfig config = new YamlConfig(age, male, company, pet1, pet2, pet3, plant, languageEL, friend, friendEL, family, playgame, quote0, quote1, quote2); 
 		System.out.println(config);
 		return config;
 	}
 }

## 输出结果 ##

YamlConfig(age=26, male=true, company=tencentQQ, pet1=null, pet2=null, pet3=null, plant=[rose, lily, sunflower, pear, lily], languageEL=[java, C#, python], friend=null, friendEL={teacher=Jane, musician=F.I.R, scientist=Einstein}, family=null, playgame=null, quote0=a tman\tof\nmany\ntalents, his age is 18 and his company is tencentQQ, quote1=a man\tof\nmany\ntalents, his age is 18 and his company is tencentQQ, quote2=a tman	of
 many
 talents, his age is 18 and his company is tencentQQ)

## 总结 ##

@Value 只适用于简单类型，如 String、int、Boolean。对于 List 和 Map 这种复杂类型，则需要借助 SpringEL 表达式来实现。因此它仅适合于获取少量且简单的属性。

# 使用 @ConfigurationProperties 批量自动装配 #

这里用到了 lombok，需要使用安装 lombok 插件，并在pom.xml 中添加 lombok 依赖

<dependency>
 <groupId>org.projectlombok</groupId>
 <artifactId>lombok</artifactId>
 <version>1.18.8</version>
 <scope>provided</scope>
 </dependency>
 <dependency>
 	<groupId>org.springframework.boot</groupId>
 	<artifactId>spring-boot-configuration-processor</artifactId>
 	<optional>true</optional>
 </dependency>

## 源代码 ##

YamlConfig.java

@NoArgsConstructor
 @AllArgsConstructor
 @Data
 @Validated //JSR303校验，例如@NotNull
 
 @Component
 //可以引用多个配置文件，中间用逗号隔开，配置文件可以以"classpath:"、或"file:"打头
 @PropertySource(value= "config/bob.yml", encoding = "utf-8", factory = MixPropertySourceFactory.class)
 @ConfigurationProperties(prefix = "person.bob", ignoreInvalidFields = true, ignoreUnknownFields = true)
 public class YamlConfig {
 	@NotNull
 	private int age;
 	private boolean male;
 	private String company;
 	private String[] pet1;
 	private List<String> pet2;
 	private Set<String> pet3;
 	
 	private List<String> plant;
 	private List<String> languageEL;
 	
 	private Map<String, String> friend;
 	@Value("#{${person.bob.friendEL}}")
 	private Map<String, String> friendEL;
 	private Map<String, String> family;
 	
 	private List<Map<String, String>> playgame;
 	
 	private String quote0;
 	private String quote1;
 	private String quote2;
 	
 }

TestController.java

@RestController
    public class TestController {
        @Autowired
        private YamlConfig config;
    
    	@GetMapping("/testConf")
    	public YamlConfig testConf() {
    		System.out.println(config);
    		return config;
    	}
    }

## 输出结果 ##

YamlConfig(age=26, male=true, company=tencentQQ, pet1=[rabbit, tortoise, carp, tortoise], pet2=[rabbit, tortoise, carp, tortoise], pet3=[rabbit, tortoise, carp], plant=[rose, lily, sunflower, pear, lily], languageEL=[java, C#, python], friend={teacher=Jane, musician=F.I.R, scientist=Einstein}, friendEL={teacher=Jane, musician=F.I.R, scientist=Einstein}, family={father=Trump, mother=Tina, brother=Tom}, playgame=[{name=GBA, years=5}, {name=Srike of Kings, years=3}, {name=Dragon Nest, years=2}], quote0=a tman\tof\nmany\ntalents, his age is 18 and his company is tencentQQ, quote1=a man\tof\nmany\ntalents, his age is 18 and his company is tencentQQ, quote2=a tman	of
 many
 talents, his age is 18 and his company is tencentQQ)

## 总结 ##

该方案可以自动装配上面列举的所有类型。如果yaml里面的是StringEL的字符串，可以配合上@Value 注解进行解析。

# 使用环境变量 Environment 装配 #

## 源代码 ##

@RestController
 //首先要声明配置文件的位置
 @PropertySource(value= "config/bob.yml", encoding = "utf-8", factory = MixPropertySourceFactory.class)
 public class TestController {
 	@Autowired
 	private Environment env;
 
 	@GetMapping("/testEnv")
 	public YamlConfig testEnv() {
 		int age = env.getProperty("person.bob.age", Integer.class);
 		boolean male = env.getProperty("person.bob.male", Boolean.class);
 		String company = env.getProperty("person.bob.company");
 
 		String[] pet1 = env.getProperty("person.bob.pet1", String[].class);
 		List<String> pet2 = env.getProperty("person.bob.pet2", List.class);
 		Set<String> pet3 = env.getProperty("person.bob.pet3", Set.class);
 		List<String> plant = env.getProperty("person.bob.plant", List.class);
 		List<String> languageEL = env.getProperty("#{'${person.bob.languageEL}'.split(',')}", List.class);
 
 		Map<String, String> friend = env.getProperty("person.bob.friend", Map.class);
 		Map<String, String> friendEL = env.getProperty("#{${person.bob.friendEL}}", Map.class);
 		Map<String, String> family = env.getProperty("person.bob.family", Map.class);
 		List<Map<String, String>> playgame = env.getProperty("person.bob.play-game", List.class);
 
 		String quote0 = env.getProperty("person.bob.quote-0");
 		String quote1 = env.getProperty("person.bob.quote-1");
 		String quote2 = env.getProperty("person.bob.quote-2");
 
 		YamlConfig config = new YamlConfig(age, male, company, pet1, pet2, pet3, plant, languageEL, friend, friendEL,
 				family, playgame, quote0, quote1, quote2);
 		System.out.println(config);
 		return config;
 	}
 }

## 输出结果 ##

![在这里插入图片描述][20190924115132978.png]

## 总结 ##

Environment 仅支持 boolean、int、string 和 list 的行内写法，功能比 @Value 还弱

[2019092310555946.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/62ba6aae35ae4d409586f50453ee1ccd.png
[20190924115132978.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/a738075c196847af830c699c67120448.png