InputStream读取数据

import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;public class Test {public static void main(String[] args) throws IOException  {File f = new File("D:/file.txt");InputStream in = new FileInputStream(f);byte[] b = new byte[in.available()];in.read(b);System.out.println(new String(b));}}