java文件读入输出问题~~~高手进啊！！！

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.Date;

public class Test11 {

public static void main(String[] args) throws Exception{
long time = copyFile(new File("d:\\test.txt"),new File("e:\\test.txt"));
System.out.println("copy file used "+ time +" milliseconds");
}

public static long copyFile(File f1, File f2) throws Exception {
long time = new Date().getTime();
int length = 2097152;
FileInputStream in = new FileInputStream(f1);
FileOutputStream out = new FileOutputStream(f2);
byte[] buffer = new byte[length];
while (true) {
int ins = in.read(buffer);
if (ins == -1) {
in.close();
out.flush();
out.close();
return new Date().getTime() - time;
} else
out.write(buffer, 0, ins);
}
}
}

public static void main(String[] args) {
File file = new File("D:\\test.txt");
FileWriter fileWriter = null;
try {
fileWriter = new FileWriter("C:\\test.txt");
FileInputStream fileInputStream = new FileInputStream(file);
InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream,"gbk");
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
String line = bufferedReader.readLine();
while(line != null){
fileWriter.write(line);
fileWriter.write("\n");
line = bufferedReader.readLine();
}
} catch (Exception e) {
e.printStackTrace();
}finally{
try {
fileWriter.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}

java.io.*; public class Demo { File file=new File(