safecopy.java

java编程开发技巧与实例的编译测试通过的所有例程

import java.io.*;

public class SafeCopy
{
	public static void copyFile(DataInputStream in, DataOutputStream out) throws IOException
	{
		try
		{
			while (true)
				out.writeByte(in.readByte());
		}
		catch	(EOFException eof)
		{
			return;
		}
	}
	public static void main(String args[])
	{
		if (args.length != 2)
			System.out.println("Usage: java Copy sourceFile targetFile");
		else
		{
			String inFileName	=	args[0], outFileName = args[1];
			File inFile	=	new File(inFileName);
			File outFile	=	new File(outFileName);
			if (!inFile.exists())
				System.out.println(inFileName + " does not exist.");
			else if (outFile.exists())
				System.out.println(outFileName + " already exists");
			else
			{
				try
				{
					DataInputStream in	=	new DataInputStream(
												new BufferedInputStream(
													new FileInputStream(inFileName)));
					DataOutputStream out	=	new DataOutputStream(
							new BufferedOutputStream(
								new FileOutputStream(outFileName)));
					copyFile(in, out);
					in.close();
					out.close();
				}
				catch	(IOException ioe)
				{
					System.out.println("Unknown error: " + ioe);
				}
			}
		}
	}
}