定义：Properties 继承于 Hashtable.表示一个持久的属性集.属性列表中每个键及其对应值都是一个字符串。

• 注意这里的持久，也就是说他可以以文件的形式存在

package com.fs.myProperties;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Properties;

public class PropertiesTest {
	public static void main(String[] args) throws IOException {
		Properties properties = new Properties();
		
		// 读
		BufferedInputStream in = new BufferedInputStream(new FileInputStream(\"test.properties\"));
		properties.load(in);
		Enumeration<?> keys = properties.propertyNames();
		while (keys.hasMoreElements()) {
			  key = ( ) keys.nextElement();
			System.out.println(key + \":\" + properties.get(key));
		}
		in.close();
		
		// 写
		BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(\"test.properties\"));
		properties.setProperty(\"sex\", \"man\");
		properties.store(out, \"sex\");
		out.close();
		
	}
}

• 项目下的test.properties文件

#sex
#Tue Oct 16 17:19:39 CST 2018
age=18
name=lzl
sex=man