Java 属性配置文件读取方法详解

一、配置文件基础概念

1. 配置文件类型对比

类型	格式	优点	缺点	适用场景
Properties	key=value	简单易读，Java原生支持	不支持层级结构	简单配置，JDBC参数
XML	标签层级结构	结构化强，支持复杂数据类型	冗余，解析复杂	复杂配置，Spring旧版本
YAML	缩进层级结构	简洁易读，支持复杂结构	依赖缩进，易出错	Spring Boot，云原生应用
JSON	键值对结构	通用性强，语言无关	无注释支持	前后端共享配置

2. 配置文件位置策略

graph TDA[配置文件位置] --> B[类路径 resources/]A --> C[文件系统绝对路径]A --> D[相对项目路径]A --> E[网络位置 URL]A --> F[JVM启动参数指定]

二、Properties 文件读取方法

1. 原生 Java 读取方式

import java.io.InputStream;
import java.util.Properties;public class PropertiesLoader {public static void main(String[] args) {Properties prop = new Properties();try (InputStream input = PropertiesLoader.class.getClassLoader().getResourceAsStream("config.properties")) {if (input == null) {throw new RuntimeException("配置文件未找到");}// 加载配置文件prop.load(input);// 获取属性值String dbUrl = prop.getProperty("database.url");int maxConnections = Integer.parseInt(prop.getProperty("pool.max_connections", "10") // 默认值);System.out.println("DB URL: " + dbUrl);System.out.println("Max Connections: " + maxConnections);} catch (Exception e) {e.printStackTrace();}}
}

2. 增强型读取工具类

import java.util.Properties;public class ConfigUtils {private static final Properties properties = new Properties();private static boolean loaded = false;static {loadProperties("application.properties");}private static void loadProperties(String fileName) {try (InputStream is = Thread.currentThread().getContextClassLoader().getResourceAsStream(fileName)) {if (is == null) {throw new FileNotFoundException(fileName + " not found");}properties.load(is);loaded = true;} catch (IOException e) {throw new RuntimeException("加载配置文件失败", e);}}// 获取字符串值public static String getString(String key) {checkLoaded();return properties.getProperty(key);}// 获取整数值（带默认值）public static int getInt(String key, int defaultValue) {try {return Integer.parseInt(getString(key));} catch (NumberFormatException e) {return defaultValue;}}// 获取布尔值public static boolean getBoolean(String key) {return Boolean.parseBoolean(getString(key));}private static void checkLoaded() {if (!loaded) {throw new IllegalStateException("配置文件未加载");}}// 热重载配置文件public static void reload() {properties.clear();loaded = false;loadProperties("application.properties");}
}

三、YAML 文件读取方法

1. SnakeYAML 库读取

<!-- Maven 依赖 -->
<dependency><groupId>org.yaml</groupId><artifactId>snakeyaml</artifactId><version>1.33</version>
</dependency>

import org.yaml.snakeyaml.Yaml;
import java.util.Map;public class YamlLoader {public static void main(String[] args) {Yaml yaml = new Yaml();try (InputStream in = YamlLoader.class.getClassLoader().getResourceAsStream("application.yml")) {// 加载为MapMap<String, Object> config = yaml.load(in);// 获取嵌套值Map<String, Object> dbConfig = (Map<String, Object>) config.get("database");String url = (String) dbConfig.get("url");// 获取列表值List<String> servers = (List<String>) config.get("servers");System.out.println("DB URL: " + url);System.out.println("Servers: " + servers);} catch (Exception e) {e.printStackTrace();}}
}

2. 绑定到 Java 对象

public class AppConfig {private Database database;private List<String> servers;private Security security;// getters and setterspublic static class Database {private String url;private String username;private String password;private int maxConnections;// getters and setters}public static class Security {private boolean enabled;private String token;// getters and setters}
}// 读取并绑定
public class YamlToObject {public static void main(String[] args) {Yaml yaml = new Yaml(new Constructor(AppConfig.class));try (InputStream in = YamlToObject.class.getClassLoader().getResourceAsStream("application.yml")) {AppConfig config = yaml.load(in);System.out.println("DB User: " + config.getDatabase().getUsername());} catch (Exception e) {e.printStackTrace();}}
}

四、Spring Boot 配置读取最佳实践

1. 基础配置绑定

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;@Component
public class DatabaseConfig {@Value("${database.url}")private String url;@Value("${database.username}")private String username;@Value("${database.password}")private String password;@Value("${pool.max_connections:20}") // 带默认值private int maxConnections;// 使用配置public void initDataSource() {System.out.println("Connecting to: " + url);}
}

2. 类型安全配置绑定

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;@Component
@ConfigurationProperties(prefix = "app")
public class AppProperties {private Database database;private List<String> servers;private Security security;// 嵌套静态类public static class Database {private String url;private String username;private String password;private int maxConnections;// getters and setters}public static class Security {private boolean enabled;private String token;// getters and setters}// getters and setters
}// application.yml
app:database:url: jdbc:mysql://localhost/dbusername: rootpassword: secretmax_connections: 50servers:- server1.example.com- server2.example.comsecurity:enabled: truetoken: abc123xyz

3. 多环境配置管理

src/main/resources/
├── application.yml          # 公共配置
├── application-dev.yml      # 开发环境
├── application-test.yml     # 测试环境
└── application-prod.yml     # 生产环境

启动参数指定环境：

java -jar myapp.jar --spring.profiles.active=prod

五、高级配置技巧

1. 动态刷新配置

import org.springframework.cloud.context.config.annotation.RefreshScope;@RefreshScope
@Component
public class DynamicConfig {@Value("${dynamic.property}")private String dynamicValue;public String getConfig() {return dynamicValue;}
}

通过 /actuator/refresh 端点刷新配置（需要 Spring Cloud）

2. 加密敏感配置

import org.jasypt.encryption.StringEncryptor;
import org.springframework.beans.factory.annotation.Autowired;public class SecureConfig {@Autowiredprivate StringEncryptor encryptor;@Value("${encrypted.property}")private String encryptedProperty;public String getDecryptedValue() {return encryptor.decrypt(encryptedProperty);}
}

3. 自定义配置源

import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.PropertySource;@Configuration
public class CustomPropertySourceConfig {@Beanpublic PropertySource<?> customPropertySource() {Map<String, Object> properties = new HashMap<>();properties.put("custom.property", "value-from-db");return new MapPropertySource("customSource", properties);}
}

六、配置读取安全最佳实践

1. 敏感信息处理

风险	解决方案	实现方式
密码明文存储	使用加密配置	Jasypt, Spring Cloud Config 加密
配置文件泄露	配置文件与代码分离	外部化配置（K8s ConfigMap, Vault）
生产配置误用	环境隔离	Spring Profiles, 独立配置文件

2. 配置审计策略

import org.springframework.boot.context.event.ApplicationReadyEvent;
import org.springframework.context.event.EventListener;@Component
public class ConfigAuditor {private final Environment env;public ConfigAuditor(Environment env) {this.env = env;}@EventListener(ApplicationReadyEvent.class)public void auditConfiguration() {System.out.println("=== 配置审计报告 ===");System.out.println("Active Profiles: " + Arrays.toString(env.getActiveProfiles()));System.out.println("DB URL: " + env.getProperty("spring.datasource.url"));System.out.println("Security Enabled: " + env.getProperty("app.security.enabled"));// 记录到审计日志...}
}

七、性能优化方案

1. 配置读取优化策略

场景	优化方案	效果
高频访问配置	缓存配置值	减少重复解析
大型配置文件	按需加载	减少启动内存占用
分布式配置	客户端缓存+版本校验	减少网络请求
敏感配置	延迟解密	启动时不暴露敏感信息

2. 高效配置缓存实现

public class ConfigCache {private static final Map<String, Object> cache = new ConcurrentHashMap<>();private static final Properties properties = new Properties();static {// 初始化加载配置try (InputStream is = ConfigCache.class.getResourceAsStream("/application.properties")) {properties.load(is);} catch (IOException e) {throw new RuntimeException("配置加载失败", e);}}// 获取缓存配置public static Object getProperty(String key) {return cache.computeIfAbsent(key, k -> {Object value = properties.get(k);if (value instanceof String) {// 处理加密值等}return value;});}// 刷新缓存public static void refresh() {cache.clear();}
}

八、配置读取完整流程示例

九、总结：配置读取最佳实践

1. 技术选型指南

场景	推荐方案
简单Java应用	Properties + 工具类
Spring Boot应用	@ConfigurationProperties
复杂配置结构	YAML + 配置类
微服务/云原生	Spring Cloud Config
高安全要求	HashiCorp Vault