这样读写文件为什么文件总是会比原来的小?头疼。解决方法

这样读写文件为什么文件总是会比原来的小?头疼。。。

Java code

public class Stream {    public static void main(String[] args) throws IOException {        FileInputStream in = new FileInputStream(new File("F:\\a.exe"));        FileOutputStream out = new FileOutputStream(new File("C:\\b.exe"));        System.out.println(in.available());        byte buf[] = new byte[1024];        int size = -1;        int sum = in.available();        while ((size=in.read(buf,0,buf.length)) != -1) {            if(size < 1024){//                System.out.println("再写入-->"+size);                out.write(size);            }else{//                System.out.println("写入-->" + size);                out.write(buf);            }        }        out.flush();        out.close();        in.close();    }}

Java code

public class Stream {    public static void main(String[] args) throws IOException {        FileInputStream in = new FileInputStream(new File("F:\\a.exe"));        FileOutputStream out = new FileOutputStream(new File("C:\\b.exe"));        System.out.println(in.available());        byte buf[] = new byte[1024];        int size = -1;        int sum = in.available();        while ((size=in.read(buf,0,buf.length)) != -1) {            out.write(buf,0,size);                    }        out.flush();        out.close();        in.close();    }}