cmd指令（三个文件放在同一路径下）

javac CopyFile.java
java CopyFile.java source.txt copy.txt

代码

package com.itranswarp.learnjava;



import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;



/**

 * Learn Java from https://www.liaoxuefeng.com/

 * 

 * @author liaoxuefeng

 */

public class CopyFile {



	public static void main(String[] args) throws IOException {

		if (args.length != 2) {

			System.err.println("Usage:\n  java CopyFile.java <source> <target>");

			System.exit(1);

		}

		copy(args[0], args[1]);

		System.out.println("Done !");

	}



	static void copy(String source, String target) throws IOException {

		// 友情提示：测试时请使用无关紧要的文件

		// TODO:

		try (InputStream input = new FileInputStream(source);

			 OutputStream output = new FileOutputStream(target))

		{

			byte[] buffer = new byte[1024];

			int n;

			String s;

			StringBuilder sb = new StringBuilder();

			while ((n = input.read(buffer)) != -1) {

				sb.append(new String(buffer, "UTF-8" ));

			}

			s = sb.toString();

			output.write(s.getBytes("UTF-8"));

		} 

	}

}