Properties属性类

属性类 Properties

Properties 类本身是 HashTable 类的子类，数据存放也是按照key和value的形式存放数据的。

public class Properties extends HashTable<Object, Object>

Properties 类的主要方法：

• public Properties() //构造一个空的属性类
• public Properties(Properties defaults) //构造一个指定属性内容的类
• public String getProperty(String key) //根据属性的key取得属性的value，如果没有key则返回null
• public String getProperty(String key, String defaultValue) //根据属性的key取得属性的value，如果没有key，则返回defaultValue
• public Object setProperty(String key, String value) //设置属性
• public void list(PrintStream ouot) //属性打印
• public void load(InputStream inStream) throws IOException //从输入流中取出全部的属性内容
• public void loadFormXML(InputStream in) throws IOException, InvalidPropertiesFormatException //从XML文件格式中读取内容
• public void store(OutputStream os, String comment) throws IOException //将属性内容通过输出流输出，同时声明属性的注释
• public void storeToXML(OutputStream os, String comment) throws IOException //以XML文件格式输出属性，默认编码
• public void storeToXML(OutputStream os, String comment, String encoding) throws IOException //以XML文件格式输出，用户指定默认编码

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

/**
 * Created by Javen on 2018/8/24.
 */
public class PropertiesDemo {
    public static void main(String args[]) {
        writePropertiesFile(); //写 Properties 文件
        readPropertiesFile();  //读 Properties 文件
    }

    public static void writePropertiesFile() {
        File file = new File("D:" + File.separator + "PropertiesDemoWrite.txt");
        File file2 = new File("D:" + File.separator + "PropertiesDemoWriteXml.txt");
        Properties properties = new Properties();
        properties.setProperty("javen", "19950601");
        properties.setProperty("nanshen", "19960101");
        properties.setProperty("kunshen", "19940101");
        properties.setProperty("zuqiang", "19940201");
        try {
            properties.store(new FileOutputStream(file), "PropertiesDemo");//写文件
            properties.storeToXML(new FileOutputStream(file2), "PropertiesDemoXml", "utf-8");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void readPropertiesFile() {
        File file = new File("D:" + File.separator + "PropertiesDemoWrite.txt");
        File file2 = new File("D:" + File.separator + "PropertiesDemoWriteXml.txt");
        Properties properties = new Properties();
        Properties properties2 = new Properties();
        try {
            properties.load(new FileInputStream(file));
            properties2.loadFromXML(new FileInputStream(file2));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        String jw = properties.getProperty("javen");
        String ns = properties.getProperty("nanshen");
        String zq = properties.getProperty("gangge");//不存在的key
        String ks = properties.getProperty("kunshen");
        System.out.println( jw + "\n" + ns + "\n" + zq + "\n" + ks);
    }
}