从属性获取整数，浮点数，布尔值和字符串 [英] Get int, float, boolean and string from Properties

问题描述

我从属性文件中获取了int，float，boolean和string。一切都已加载到属性中。目前，我正在解析我所知道的特定键的期望值。

I have int, float, boolean and string from Properties file. Everything has loaded in Properties. Currently, I am parsing values as I know expected value for particular key.

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

设置这些常量值的更好方法是，如果我不知道什么是键的原始值数据类型。

What is better way of setting these constants values, If I don't know what could be primitive value datatype for a key.

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。
messassge.properties

Properties File. messassge.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

Constant.java

Constant.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;
}

推荐答案

如果您有配置值，例如 Constants 类，并且要从配置（属性）文件中加载所有值，可以创建一个小助手类并使用反射：

If you have a class of configuration values, like your Constants class, and you want to load all values from a configuration (properties) file, you can create a little helper class and use reflection:

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());
    }
}

然后您这样称呼：

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

您可以扩展代码以处理更多类型。您还可以更改它以忽略缺少的属性，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，即是默认设置。

You can extend the code to handle more types. You can also change it to ignore missing properties, instead of failing like it does now, such that assignments in the field declaration will remain unchanged, i.e. be the default.

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