Java 屬性配置文件讀取方法詳解

一、配置文件基礎概念

1. 配置文件類型對比

類型	格式	優點	缺點	適用場景
Properties	key=value	簡單易讀，Java原生支持	不支持層級結構	簡單配置，JDBC參數
XML	標簽層級結構	結構化強，支持復雜數據類型	冗余，解析復雜	復雜配置，Spring舊版本
YAML	縮進層級結構	簡潔易讀，支持復雜結構	依賴縮進，易出錯	Spring Boot，云原生應用
JSON	鍵值對結構	通用性強，語言無關	無注釋支持	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[類路徑 resources/]A --> C[文件系統絕對路徑]A --> D[相對項目路徑]A --> E[網絡位置 URL]A --> F[JVM啟動參數指定]

二、Properties 文件讀取方法

1. 原生 Java 讀取方式

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");}// 加載配置文件prop.load(input);// 獲取屬性值String dbUrl = prop.getProperty("database.url");int maxConnections = Integer.parseInt(prop.getProperty("pool.max_connections", "10") // 默認值);System.out.println("DB URL: " + dbUrl);System.out.println("Max Connections: " + maxConnections);} catch (Exception e) {e.printStackTrace();}}
}

2. 增強型讀取工具類

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("加載配置文件失敗", e);}}// 獲取字符串值public static String getString(String key) {checkLoaded();return properties.getProperty(key);}// 獲取整數值（帶默認值）public static int getInt(String key, int defaultValue) {try {return Integer.parseInt(getString(key));} catch (NumberFormatException e) {return defaultValue;}}// 獲取布爾值public static boolean getBoolean(String key) {return Boolean.parseBoolean(getString(key));}private static void checkLoaded() {if (!loaded) {throw new IllegalStateException("配置文件未加載");}}// 熱重載配置文件public static void reload() {properties.clear();loaded = false;loadProperties("application.properties");}
}

三、YAML 文件讀取方法

1. SnakeYAML 庫讀取

<!-- Maven 依賴 -->
<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")) {// 加載為MapMap<String, Object> config = yaml.load(in);// 獲取嵌套值Map<String, Object> dbConfig = (Map<String, Object>) config.get("database");String url = (String) dbConfig.get("url");// 獲取列表值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. 綁定到 Java 對象

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}
}// 讀取并綁定
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 配置讀取最佳實踐

1. 基礎配置綁定

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}") // 帶默認值private int maxConnections;// 使用配置public void initDataSource() {System.out.println("Connecting to: " + url);}
}

2. 類型安全配置綁定

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;// 嵌套靜態類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. 多環境配置管理

src/main/resources/
├── application.yml          # 公共配置
├── application-dev.yml      # 開發環境
├── application-test.yml     # 測試環境
└── application-prod.yml     # 生產環境

啟動參數指定環境：

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

五、高級配置技巧

1. 動態刷新配置

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

通過 /actuator/refresh 端點刷新配置（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. 自定義配置源

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、配置讀取安全最佳實踐

1. 敏感信息處理

風險	解決方案	實現方式
密碼明文存儲	使用加密配置	Jasypt, Spring Cloud Config 加密
配置文件泄露	配置文件與代碼分離	外部化配置（K8s ConfigMap, Vault）
生產配置誤用	環境隔離	Spring Profiles, 獨立配置文件

2. 配置審計策略

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("=== 配置審計報告 ===");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"));// 記錄到審計日志...}
}

七、性能優化方案

1. 配置讀取優化策略

場景	優化方案	效果
高頻訪問配置	緩存配置值	減少重復解析
大型配置文件	按需加載	減少啟動內存占用
分布式配置	客戶端緩存+版本校驗	減少網絡請求
敏感配置	延遲解密	啟動時不暴露敏感信息

2. 高效配置緩存實現

public class ConfigCache {private static final Map<String, Object> cache = new ConcurrentHashMap<>();private static final Properties properties = new Properties();static {// 初始化加載配置try (InputStream is = ConfigCache.class.getResourceAsStream("/application.properties")) {properties.load(is);} catch (IOException e) {throw new RuntimeException("配置加載失敗", e);}}// 獲取緩存配置public static Object getProperty(String key) {return cache.computeIfAbsent(key, k -> {Object value = properties.get(k);if (value instanceof String) {// 處理加密值等}return value;});}// 刷新緩存public static void refresh() {cache.clear();}
}

八、配置讀取完整流程示例

九、總結：配置讀取最佳實踐

1. 技術選型指南

場景	推薦方案
簡單Java應用	Properties + 工具類
Spring Boot應用	@ConfigurationProperties
復雜配置結構	YAML + 配置類
微服務/云原生	Spring Cloud Config
高安全要求	HashiCorp Vault