我有一些代码使用了一个包含大量硬编码常量的类。这是它的样子:
class Constants{
public static final String name1 = "value1";
public static final String name2 = "value2";
public static final Integer value3 = 3;
... and so on
}
这些常量在代码中无处不在,如 Constants.name1
。
我现在需要做的是使在配置文件中为这些常量指定值成为可能,可能是 *.properties
文件。
我的问题是:最好的方法是什么,必须尽可能少地重写代码?
我想过使用一个配置类,它在实例化时从文件中读取属性,但是我必须将所有静态值调用替换为对该类实例的调用,并且我必须更改现有方法将此配置实例传递给它们。有没有更好的办法?
最佳答案
这是我过去使用过的一段代码 - 可以根据您的示例进行调整:
public enum Configuration {
PROPERTY1("property1.name", "default_value_1"),
PROPERTY2("property2.name", "default_value_2");
private final String key;
private String defaultValue;
Configuration(String key) {
this(key, NA);
}
Configuration(String key, String defaultValue) {
this.key = key;
this.defaultValue = defaultValue;
}
private final static Logger logger = LoggerFactory.getLogger(Configuration.class);
private final static String NA = "n.a.";
private final static String CONFIG_FILE = "properties/config.properties";
private final static String NOT_A_VALID_KEY = "Not a valid property key";
private final static Map<Configuration, String> configuration = new EnumMap<>(Configuration.class);
static {
readConfigurationFrom(CONFIG_FILE);
}
private static void readConfigurationFrom(String fileName) {
logger.info("Reading resource: {}", fileName);
try (InputStream resource = Configuration.class.getClassLoader().getResourceAsStream(fileName);) {
Properties properties = new Properties();
properties.load(resource); //throws a NPE if resource not founds
for (String key : properties.stringPropertyNames()) {
configuration.put(getConfigurationKey(key), properties.getProperty(key));
}
} catch (IllegalArgumentException | IOException | NullPointerException e) {
logger.error("Error while reading the properties file {}", fileName, e);
populateDefaultValues();
}
}
private static Configuration getConfigurationKey(String key) {
for (Configuration c : values()) {
if (c.key.equals(key)) {
return c;
}
}
throw new IllegalArgumentException(NOT_A_VALID_KEY + ": " + key);
}
private static void populateDefaultValues() {
for (Configuration c : values()) {
configuration.put(c, c.defaultValue);
}
}
/**
* @return the property corresponding to the key or null if not found
*/
public String get() {
return configuration.get(this);
}
}
关于java - 如何从硬编码的静态配置文件切换到 .properties 文件?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/17809130/