Java最佳实践建议将属性作为常量读取.那么,您认为达到目标的最佳方法是什么？我的方法是：一个Configuration类只读取一次属性文件(单例模式),并使用此类在需要时读取属性作为常量.并存储一个Constants类：
>属性名称可在属性文件中找到它们(例如app.database.url).
>静态常量(我不希望用户配置的静态常量,例如
CONSTANT_URL = “myurl.com”).
public final class Configurations {
private Properties properties = null;
private static Configurations instance = null;
/** Private constructor */
private Configurations (){
this.properties = new Properties();
try{
properties.load(Thread.currentThread().getContextClassLoader().getResourceAsStream(Constants.PATH_CONFFILE));
}catch(Exception ex){
ex.printStackTrace();
}
}
/** Creates the instance is synchronized to avoid multithreads problems */
private synchronized static void createInstance () {
if (instance == null) {
instance = new Configurations ();
}
}
/** Get the properties instance. Uses singleton pattern */
public static Configurations getInstance(){
// Uses singleton pattern to guarantee the creation of only one instance
if(instance == null) {
createInstance();
}
return instance;
}
/** Get a property of the property file */
public String getProperty(String key){
String result = null;
if(key !=null && !key.trim().isEmpty()){
result = this.properties.getProperty(key);
}
return result;
}
/** Override the clone method to ensure the "unique instance" requeriment of this class */
public Object clone() throws CloneNotSupportedException {
throw new CloneNotSupportedException();
}}
Constant类包含对属性和常量的引用.
public class Constants {
// Properties (user configurable)
public static final String DB_URL = "db.url";
public static final String DB_DRIVER = "db.driver";
// Constants (not user configurable)
public static final String PATH_CONFFILE = "config/config.properties";
public static final int MYCONSTANT_ONE = 1;
}
db.url=www.myurl.com db.driver=MysqL
要读取属性和常量将是：
// Constants int i = Constants.MYCONSTANT_ONE; // Properties String url = Configurations.getInstance().getProperty(Constants.DB_URL);
你认为这是一个好方法吗？在Java中读取属性和常量的方法是什么？
提前致谢.
解决方法
我找到了一个更好的解决方案来均化代码并将所有内容都作为常量.使用相同的Configurations类和.properties文件：由于getInstance()方法是静态的,因此可以在类Constants中初始化常量.
public class Properties {
// Properties (user configurable)
public static final String DB_URL = "db.url";
public static final String DB_DRIVER = "db.driver";
}
然后Constant类将是：
public class Constants {
// Properties (user configurable)
public static final String DB_URL = Configurations.getInstance().getProperty(Properties.DB_URL);
public static final String DB_DRIVER = Configurations.getInstance().getProperty(Properties.DB_DRIVER );
// Constants (not user configurable)
public static final String PATH_CONFFILE = "config/config.properties";
public static final int MYCONSTANT_ONE = 1;
}
最后使用它们：
// Constants int i = Constants.MYCONSTANT_ONE; // Properties String url = Constants.DB_URL;
