使用BufferedInputStream读取文件通常比FileInputStream快，因为它维护内部缓冲区以存储从基础输入流读取的字节。

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.IOException;
public class FileReadingDemo {
      public static void main(String[] args) {
          String source = "hello.txt";
          try (BufferedInputStream bis = new    BufferedInputStream(new FileInputStream(source))) {
              byte data;
              while ((data = (byte) bis.read()) != -1) {
                     System.out.println((char) data);
              }
           } catch (IOException e) {
                   e.printStackTrace();
           }
     }
}