filecopy.java

这是一个用java编写类似于notepad文件编辑器

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class FileCopy {

	public static void copy(String from_name, String to_name)
		throws IOException {

		File from_file = new File(from_name);
		File to_file = new File(to_name);

		if (!from_file.canRead())
			abort("源文件不是可读文件： " + from_name);

		if (to_file.exists()) {
			if (!to_file.canWrite())
				abort("目标文件不是可写文件：" + to_name);

		}

		//这时开始复制文件。
		FileInputStream from = null; 
		FileOutputStream to = null; 			 
		try {
			from = new FileInputStream(from_file);	 //创建输入流
			to = new FileOutputStream(to_file);		 //创建输出流
			byte[] buffer = new byte[4096];
			int bytes_read; 						//缓存中的字节数目
															//将一段字节流读到缓存中，然后将它们写出来
															//，循环直到文件末尾（当read()返回-1时）停止
			while ((bytes_read = from.read(buffer)) != -1) //读取流直到文件末尾
				to.write(buffer, 0, bytes_read); //写入
		}

		//关闭流
		finally {
			if (from != null)
				try {
					from.close();
				} catch (IOException e) {
					;
				}
			if (to != null)
				try {
					to.close();
				} catch (IOException e) {
					;
				}
		}
	}

	 
	private static void abort(String msg) throws IOException {
		throw new IOException("文件复制： " + msg);
	}
}