读取文件以确定其包含的字节数，然后用0覆盖所有这些字节

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;/*n o w j a v a . c o m - 时代Java 提供*/


public class Main {

  public static void main(String[] arguments) {

    try {

      FileInputStream file = new FileInputStream("junkfile.dat");

      boolean eof = false;

      int size = 0;

      while (!eof) {

        int input = file.read();

        if (input == -1) {

          eof = true;
          /*
          时   代    Java - nowjava.com 提供
          */

        } else {

          size++;

        }

      }

      file.close();

      FileOutputStream outFile = new FileOutputStream("junkfile.dat");

      for (int i = 0; i < size; i++) {

        outFile.wr