java Properties属性集类介绍

Properties间接实现了Map接口，它可以从文件当中加载内容到集合当中。

简单使用案例

public class Test {
    public static void main(String[] args) {
        
        Properties properties = new Properties();
        properties.setProperty("account","12345678");
        properties.setProperty("password","123456");

        //获取所有的键
        Set keys = properties.stringPropertyNames();
        //keys.forEach(System.out::println);
        for (String key : keys) {
            //根据键找值
            System.out.println(key+":"+properties.getProperty(key));
        }
    }
}

结合字符流或者字节流来加载配置文件内容

public class Test2 {
    public static void main(String[] args) {
        
        try (
                //如果配置文件中有 中文那么使用字符流
                FileInputStream fileInputStream = new FileInputStream("Properties属性集类\config\db.properties");
                ){
            Properties properties = new Properties();
            //把文件加载到properties中
            properties.load(fileInputStream);
            System.out.println(properties.getProperty("username"));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

写入配置文件

public class Test3 {
    public static void main(String[] args) throws IOException {
        
        Properties properties = new Properties();

        properties.setProperty("username","zhanghao");
        properties.setProperty("password","123456");
        FileOutputStream fileOutputStream = new FileOutputStream("Properties属性集类\config\test.properties");
        //写入数据到文件
        properties.store(fileOutputStream,"这是一个注释");
        fileOutputStream.close();
    }
}