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

public class PropertiesDemo {
  public static void main(String[] args)
  {
    String pFilename = System.getProperty("user.dir")
      + System.getProperty("file.separator") + "test.properties"; // 构造文件名
    Properties p = new Properties();  

    try
    {
      FileInputStream in = new FileInputStream(pFilename);  // 构造文件的输入流
      p.load(in);           // 读入属性
      in.close();
    }
    catch(Exception e)
    {
      System.out.println("Error of create input stream");
    }

    System.out.println(p.getProperty("property1"));
    p.setProperty("property1","new value"); // 给property1赋新的值

    try
    {
      FileOutputStream out = new FileOutputStream(pFilename);
      p.store(out,"This file is a test"); // 设置属性文件的文件头信息
      out.flush();
      out.close();
    }
    catch(Exception e)
    {
      System.out.println("Error of write input stream");
    }
  }
}