java - 从属性中获取 int、float、boolean 和 string

Question

我有来自属性文件的 int、float、boolean 和 string。一切都已加载到属性中。目前，我正在解析值，因为我知道特定键的预期值。

Boolean.parseBoolean("false");
Integer.parseInt("3")

如果我不知道键的原始值数据类型是什么，那么设置这些常量值的更好方法是什么。

public class Messages {

    Properties appProperties = null;
    FileInputStream file = null;

    public void initialization() throws Exception {

        appProperties = new Properties();
        try {

            loadPropertiesFile();

        } catch (Exception e) {
            throw new Exception(e.getMessage(), e);
        }
    }

    public void loadPropertiesFile() throws IOException {

        String path = "./cfg/message.properties";
        file = new FileInputStream(path);
        appProperties.load(file);
        file.close();
    }
}

属性文件。message.properties

SSO_URL = https://example.com/connect/token
SSO_API_USERNAME = test
SSO_API_PASSWORD = Uo88YmMpKUp
SSO_API_SCOPE = intraday_api
SSO_IS_PROXY_ENABLED = false
SSO_MAX_RETRY_COUNT = 3
SSO_FLOAT_VALUE = 3.0

常量.java

public class Constants {
    public static String SSO_URL = null;
    public static String SSO_API_USERNAME = null;
    public static String SSO_API_PASSWORD = null;
    public static String SSO_API_SCOPE = null;
    public static boolean SSO_IS_PROXY_ENABLED = false;
    public static int SSO_MAX_RETRY_COUNT = 0;
    public static float SSO_FLOAT_VALUE = 0;
}

Answer 1

如果你有一个配置值类，比如你的 Constants 类，并且你想从配置(属性)文件中加载所有值，你可以创建一个小助手类并使用反射:

public class ConfigLoader {
    public static void load(Class<?> configClass, String file) {
        try {
            Properties props = new Properties();
            try (FileInputStream propStream = new FileInputStream(file)) {
                props.load(propStream);
            }
            for (Field field : configClass.getDeclaredFields())
                if (Modifier.isStatic(field.getModifiers()))
                    field.set(null, getValue(props, field.getName(), field.getType()));
        } catch (Exception e) {
            throw new RuntimeException("Error loading configuration: " + e, e);
        }
    }
    private static Object getValue(Properties props, String name, Class<?> type) {
        String value = props.getProperty(name);
        if (value == null)
            throw new IllegalArgumentException("Missing configuration value: " + name);
        if (type == String.class)
            return value;
        if (type == boolean.class)
            return Boolean.parseBoolean(value);
        if (type == int.class)
            return Integer.parseInt(value);
        if (type == float.class)
            return Float.parseFloat(value);
        throw new IllegalArgumentException("Unknown configuration value type: " + type.getName());
    }
}

那你这样调用它:

ConfigLoader.load(Constants.class, "/path/to/constants.properties");

您可以扩展代码以处理更多类型。您还可以将其更改为忽略缺少的属性，而不是像现在这样失败，这样字段声明中的分配将保持不变，即成为默认值。