锚点和引用
YAML允许我们定义一个锚点并在其他地方引用, 方便重复配置
defaults: &defaults
timeout: 30
retries: 3
development:
<<: *defaults
server: dev.example.com
production:
<<: *defaults
server: prod.example.com
timeout: 60复杂列表
字面意思就是列表可以包含复杂对象
employees:
- name: John Doe
position: Developer
skills:
- Java
- Spring
- name: Jane Smith
position: Designer
skills:
- UI/UX
- Photoshop多文档YAML
在一个YAML文件中可以定义多个文档, 用---分隔
server:
port: 8080
---
spring:
profiles: test
server:
port: 9090
---
spring:
profiles: prod
server:
port: 80环境变量和占位符
YAML 支持使用环境变量和 Spring 的属性占位符
app:
name: MyApp
description: ${APP_DESCRIPTION:Default description}
config-location: ${user.home}/config使用 @ConfigurationProperties 绑定 YAML 配置
myapp:
security:
enabled: true
token: abc123
roles:
- USER
- ADMIN
datasource:
url: jdbc:mysql://localhost/db
username: user
password: pass对应的Java类
@ConfigurationProperties(prefix = "myapp")
public class MyAppProperties {
private Security security = new Security();
private Datasource datasource = new Datasource();
// getters and setters
public static class Security {
private boolean enabled;
private String token;
private List<String> roles = new ArrayList<>();
// getters and setters
}
public static class Datasource {
private String url;
private String username;
private String password;
// getters and setters
}
}条件配置
YAML可以与SpringBoot的条件注解配合使用
myapp:
feature:
enabled: true
---
spring:
profiles: development
myapp:
feature:
enabled: false对应的Java代码
@Configuration
@ConditionalOnProperty(name = "myapp.feature.enabled", havingValue = "true")
public class FeatureConfig {
// 配置代码
}外部YAML文件
可以使用@PropertySource注解加载外部YAML文件, 但是需要自定义一个PropertySourceFactory
@Configuration
@PropertySource(value = "classpath:custom.yml", factory = YamlPropertySourceFactory.class)
public class YamlConfig {
// 配置代码
}列表的替代语法
YAML还支持流式语法来表示列表
fruits: [apple, banana, orange]🌰
下面来看一个栗子, 假设我们有一个电子商务应用, 需要配置数据库, 缓存, 安全设置和一些自定义属性. 这里有一个综合的application.yml文件示例
# 全局配置
spring:
application:
name: ecommerce-app
# 默认配置
defaults: &defaults
app:
security:
jwt-expiration: 3600000
jwt-secret: ${JWT_SECRET:defaultSecret}
# 开发环境配置
---
spring:
config:
activate:
on-profile: dev
datasource:
url: jdbc:mysql://localhost:3306/ecommerce_dev
username: dev_user
password: ${DB_PASSWORD}
cache:
type: simple
server:
port: 8080
logging:
level:
root: INFO
com.example.ecommerce: DEBUG
<<: *defaults
app:
feature-flags:
new-user-promo: true
payment-gateway:
url: https://dev.payment-gateway.com
api-key: ${PAYMENT_API_KEY}
product-service:
cache-ttl: 3600 # 秒
notification:
email:
from: noreply@example.com
templates:
- welcome
- order-confirmation
sms:
enabled: false
# 生产环境配置
---
spring:
config:
activate:
on-profile: prod
datasource:
url: jdbc:mysql://${DB_HOST:localhost}:3306/ecommerce_prod
username: ${DB_USER}
password: ${DB_PASSWORD}
cache:
type: redis
redis:
host: ${REDIS_HOST}
port: 6379
server:
port: 80
logging:
level:
root: WARN
com.example.ecommerce: INFO
<<: *defaults
app:
feature-flags:
new-user-promo: false
payment-gateway:
url: https://payment-gateway.com
api-key: ${PAYMENT_API_KEY}
product-service:
cache-ttl: 7200 # 秒
notification:
email:
from: support@example.com
templates:
- welcome
- order-confirmation
- feedback-request
sms:
enabled: true
provider: twilio解析:
- 多环境配置(这里配置了开发环境和生产环境)
- 使用了锚点和引用(<<: *defaults)
- 环境变量和默认值(如 ${JWT_SECRET:defaultSecret})
- 复杂的嵌套结构
- 使用了列表(如 email templates) 6.使用了条件配置(如 feature flags)
- 外部化敏感信息(如数据库密码和API密钥)
对应的Java配置类可能如下
@Configuration
@ConfigurationProperties(prefix = "app")
public class AppConfig {
private Security security = new Security();
private FeatureFlags featureFlags = new FeatureFlags();
private PaymentGateway paymentGateway = new PaymentGateway();
private ProductService productService = new ProductService();
private Notification notification = new Notification();
// getters and setters
public static class Security {
private long jwtExpiration;
private String jwtSecret;
// getters and setters
}
public static class FeatureFlags {
private boolean newUserPromo;
// getters and setters
}
public static class PaymentGateway {
private String url;
private String apiKey;
// getters and setters
}
public static class ProductService {
private int cacheTtl;
// getters and setters
}
public static class Notification {
private Email email = new Email();
private Sms sms = new Sms();
// getters and setters
public static class Email {
private String from;
private List<String> templates;
// getters and setters
}
public static class Sms {
private boolean enabled;
private String provider;
// getters and setters
}
}
}这个例子展示了如何使用 YAML 来管理复杂的应用配置，包括多环境设置、安全配置、特性开关等。它还展示了如何使用 @ConfigurationProperties 来将这些配置绑定到 Java 对象上。
在Java当中使用配置
下面我们结合下上面🌰子来演示下如何在代码当中获取这些配置值
使用@Value注解
@Value是最简单的方式, 适合获取单个配置值
@RestController
public class PaymentController {
@Value("${app.payment-gateway.url}")
private String paymentGatewayUrl;
@GetMapping("/payment-url")
public String getPaymentUrl() {
return "Payment gateway URL: " + paymentGatewayUrl;
}
}使用@ConfigurationProperties
@Configuration
@ConfigurationProperties(prefix = "app")
public class AppConfig {
private Notification notification;
// getter and setter for notification
public static class Notification {
private Email email;
private Sms sms;
// getters and setters
public static class Email {
private String from;
private List<String> templates;
// getters and setters
}
public static class Sms {
private boolean enabled;
private String provider;
// getters and setters
}
}
}@Service
public class NotificationService {
private final AppConfig.Notification notificationConfig;
public NotificationService(AppConfig appConfig) {
this.notificationConfig = appConfig.getNotification();
}
// ... 其他方法 ...
}使用Enviroment对象
对于需要动态访问配置的场景
@Service
public class FeatureFlagService {
private final Environment env;
public FeatureFlagService(Environment env) {
this.env = env;
}
public boolean isFeatureEnabled(String featureName) {
return env.getProperty("app.feature-flags." + featureName, Boolean.class, false);
}
}在配置类中使用
@Configuration
@EnableCaching
public class CacheConfig {
@Value("${app.product-service.cache-ttl}")
private int cacheTtl;
@Bean
public CacheManager cacheManager() {
return new ConcurrentMapCacheManager() {
@Override
protected Cache createConcurrentMapCache(String name) {
return new ConcurrentMapCache(
name,
CacheBuilder.newBuilder().expireAfterWrite(cacheTtl, TimeUnit.SECONDS).build().asMap(),
false);
}
};
}
}在条件注解中使用
@Configuration
@ConditionalOnProperty(name = "app.feature-flags.new-user-promo", havingValue = "true")
public class NewUserPromoConfig {
@Bean
public PromoService promoService() {
return new PromoService();
}
}在测试中使用
@SpringBootTest
@ActiveProfiles("dev")
public class PaymentServiceTest {
@Autowired
private Environment env;
@Test
public void testPaymentGatewayUrl() {
String expectedUrl = "https://dev.payment-gateway.com";
String actualUrl = env.getProperty("app.payment-gateway.url");
assertEquals(expectedUrl, actualUrl);
}
}