字节流

package fileStreamDemo;import java.io.*;class FileStreamDemo {public static void main(String[] args)  throws IOException {readFile1();readFile2();readFile3();}    //从文件读出数据的方法二：如果文件过大不能使用，很容易发生内存溢出public static void readFile3() throws IOException{FileInputStream fis=new FileInputStream("fos.txt");int len=fis.available();byte[] by=new byte[len];fis.read(by);System.out.print(new String(by));}//从文件读出数据的方法一public static void readFile2() throws IOException{FileInputStream fis=new FileInputStream("fos.txt");int len=0;byte[] by=new byte[1024];while((len=fis.read(by))!=-1){System.out.print(new String(by,0,len));}}//将数据写入文件public static void readFile1() throws IOException {FileOutputStream fos=new FileOutputStream("fos.txt");fos.write("abkasdfj".getBytes());fos.close();}}