package bxd;

import java.io.IOException;
import java.util.Properties;
import java.util.Set;

/*
Properties是hashtable的子类, 也就是说它具备map集合的特点, 而且它里面存储的键值对都是字符串, 是集合中和IO技术相结合的集合容器.
该对象的特点: 可以用于键值对形式的配置文件
*/
public class PropertiesDemo_1 {

    // 以下方法没有关联文件, 都是在内存对象中进行操作
    public static void setAndGet() {
        Properties properties = new Properties();

        // 设置Properties元素
        properties.setProperty("zhangsan", "30");
        properties.setProperty("lisi", "40");
        System.out.println(properties);

        // 获取Properties值
        System.out.println("getProperty(\"zhangsan\"): " + properties.getProperty("zhangsan"));
        System.out.println("getProperty(\"lisi\"): " + properties.getProperty("lisi"));

        // 修改Properties值
        properties.setProperty("lisi", "89");
        Set<String> names = properties.stringPropertyNames();
        for (String s : names) {
            System.out.println(s + ":" + properties.getProperty(s));
        }
    }

    public static void main(String[] args) throws IOException {
        setAndGet();
    }
}

package bxd;

import java.io.*;
import java.util.Properties;

public class PropertiesDemo_2 {

    // 演示: 如何将流中的数据存储到集合中, 想要将message.properties中键值数据存到集合中继续操作
    // 1. 用一个输入流和文件进行关联
    // 2. 读取一行数据, 将该行数据以"="作为分隔符进行切分, 结果存入字符串数组
    // 3. 等号左边为键, 右边为值, 存入到Properties对象中
    public static void method_1() throws IOException {
        Properties properties = new Properties();
        BufferedReader bufr = new BufferedReader(new FileReader("messages.properties"));

        String line;
        while ((line = bufr.readLine()) != null) {
            String[] arr = line.split("=");
            properties.setProperty(arr[0], arr[1]);
        }
        System.out.println(properties);
    }

    public static void loadDemo() throws IOException {
        Properties properties = new Properties();
        FileInputStream fis = new FileInputStream("messages.properties");

        // 加载
        properties.load(fis);
        System.out.println(properties);

        // 打印, This method is useful for debugging.
        properties.list(System.out);
    }

    public static void storeDemo() throws IOException {
        Properties properties = new Properties();
        FileOutputStream fileOutputStream = new FileOutputStream("info.txt");
        properties.setProperty("key_one", "value_one");

        // 保存
        properties.store(fileOutputStream, "just for test");
    }

    public static void main(String[] args) throws IOException {
        storeDemo();
    }
}