加载properties文件

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

public class Main {
    private static Main main = new Main();
    private Main(){}
    public static Main getMain() {
        return main;
    }
    public static Properties prop = null;
    // 静态加载配置文件
    static {
         prop = new Properties();
        ClassLoader classLoader = Main.class.getClassLoader();
        InputStream inputStream = classLoader.getResourceAsStream("config.properties");
        try {
            prop.load(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    // 给properties中设置值
    public static void modifyConfig(String key, String value) {
        try {
            // 从输入流中读取属性列表（键和元素对）
            prop.setProperty(key, value);
            String path = Main.class.getResource("/config.properties").getPath();
            FileOutputStream outputFile = new FileOutputStream(path);
            prop.store(outputFile, "modify");
            outputFile.close();
            outputFile.flush();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    // 通过key获取值
    public static String getValueByKey(String key) {
        if(prop.get(key)!=null) {
            return (String) prop.get(key);
        }
        return null;
    }
}