Java 单例模式获取Properties文件内容_java通过单例实现读取数据库配置文件详解

配置文件的获取，简单的小工具

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
 
public class PropertiesUtil {
	
	private static Properties properties;
	// 采用静态内部类构建单例模式
	private static class LazyHolder {    
	       private static final PropertiesUtil INSTANCE = new PropertiesUtil();    
	}    
    private PropertiesUtil (){}   
    // 当调用该方法实例化的时候，才会创建该类，懒加载
    public static final PropertiesUtil getInstance() {    
       return LazyHolder.INSTANCE;    
    }
	
	static{
		properties = new Properties();
		InputStream is = null;
		// 配置文件为当前类的class文件下
		is = PropertiesUtil.class.getResourceAsStream("config.properties");
		try {
			properties.load(is);
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				is.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
 
	public static void main(String[] args) {
		System.out.println(properties.getProperty("username"));
	}
 
}