Properties类继承HashTable类，一般用来给程序配置属性文件。

package com.itcast.demo04.Prop;

import jdk.internal.util.xml.impl.ReaderUTF8;
import sun.nio.cs.UTF_32;
import sun.nio.cs.ext.GBK;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Properties;
import java.util.Set;

/**
 * @author newcityman
 * @date 2019/7/28 - 12:50
 */
public class Demo01Properties {
    public static void main(String[] args) throws IOException {
//        show01();
//        show02();
        show03();

    }

    private static void show03() throws IOException {
        Properties prop = new Properties();
        prop.load(new FileReader("day18_IOAndProperties\prop.txt"));
        Set<String> key = prop.stringPropertyNames();
        for (String s : key) {
            String value = prop.getProperty(s);
            System.out.println(s+"==>"+value);
        }
    }

    private static void show02() throws IOException {
        Properties prop = new Properties();
        prop.setProperty("张曼玉","16");
        prop.setProperty("张学友","20");
        prop.setProperty("刘德华","18");

        FileWriter fw = new FileWriter("day18_IOAndProperties\prop.txt");

        prop.store(fw, "data");
    }


    private static void show01() {
        Properties prop = new Properties();
        prop.setProperty("zmy","12");
        prop.setProperty("zyy","20");
        prop.setProperty("lm","15");
        prop.setProperty("zgh","16");
        Set<String> strings = prop.stringPropertyNames();
        for (String key : strings) {
            String value = prop.getProperty(key);
            System.out.println(key+"====>"+value);
        }

    }
}