properties檔案的讀取封裝

Java Properties資源配置封裝Get

Spring容器注入ConfigurationContext前提下擷取配置檔案變量：

private static final String STRING = ConfigurationContext.getValue("keyName");
           

 封裝如下：

public class ConfigurationContext {

    private volatile Properties properties;

    private volatile static ConfigurationContext context;
    //配置檔案名
    private static final String DEFAULT_CONFIG_FILE = "config.properties";
    
    private ConfigurationContext(String fileName) throws IOException {
        ClassLoader classLoader = ConfigurationContext.class.getClassLoader();
        InputStream resourceAsStream = classLoader.getResourceAsStream(fileName);
        if (resourceAsStream == null) {
            throw new FileNotFoundException("Cannot find configuration file: " + fileName);
        }
        this.properties = new Properties();
        this.properties.load(resourceAsStream);
    }

    public static ConfigurationContext init(String fileName) throws IOException {
        if (ConfigurationContext.context == null) {
            ConfigurationContext.context = new ConfigurationContext(fileName);
        }
        return ConfigurationContext.context;
    }
    //Spring容器初始化指定調用方法
    public static ConfigurationContext init() throws IOException {
        return init(DEFAULT_CONFIGURATION_FILE);
    }
    //擷取變量 return為字元串 ，可重載return 指定Type類型
    public static String getValue(String key) {
        isInitialized();
        return ConfigurationContext.context.properties.getProperty(key);
    }

    private static void isInitialized() {
        if (ConfigurationContext.context == null) {
            throw new RuntimeException("ConfigurationContext instance haven't been initialized");
        }
    }


}
           

注入Spring容器需設定：

<!-- 系統配置上下文元件 這裡name對該封裝可有可無 -->
<bean name="configurationContext" class="********.ConfigurationContext" 
      factory-method="init" >
</bean>