流

 餐厅点菜

package review;

import java.util.*;
import java.io.*;
public class Main {
	public static void main(String[]args) throws IOException
	{
		BufferedReader ino = null;
		BufferedReader inp = null;
		Map<String,Integer> price = new HashMap<>();
		long sum = 0;
		ino = new BufferedReader(new InputStreamReader(new FileInputStream("orders.txt")));
		inp = new BufferedReader(new InputStreamReader(new FileInputStream("price.txt")));
		while(inp.ready())
		{
					String s = inp.readLine();
					String ss[] = s.split(":");
					int pri = Integer.parseInt(ss[ss.length-1]);
					price.put(ss[0], pri);

		}
		inp.close();
	
		while(ino.ready())
		{
			String s = ino.readLine();
			String ord[] = s.split(",");
 			for(int i = 0; i < ord.length; i++)
 			{
 				String or[] = ord[i].split(":");
 				String s1 = or[0];
 				String s2 = or[1];
 				int pri = Integer.parseInt(s2);
 				sum+=pri*price.get(s1);
 			}
		}
		ino.close();
		System.out.println(sum);
	}
}

定向输入到文件 

import java.io.*;
public class Test
{
	public static void main(String []args) 
	{
		BufferedReader in;
		BufferedWriter out;
		try
		{
			in = new BufferedReader(new InputStreamReader(System.in));
			out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("log.txt")));
			String s;
			while((s = in.readLine())!=null)
			{
				System.out.println(s);
				if(s.equals("exit")||s.equals("EXIT")) break;
				out.write(s);
				out.newLine();
			}
			out.flush();
			out.close();
		}catch(IOException e)
		{
			e.printStackTrace();
		}		
	}
}