Java中 IO中的字节输入流InputStream,字节输出流InputStream

package cn.mdln.study2;
import java.io.File;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.FileOutputStream;
import java.io.FileInputStream;
/**
 * IO中的字节输入流InputStream,字节输出流InputStream
 */
public class TestDemo6 {


public static void main(String[] args)throws Exception {
File file=new File("D:"+File.separator+"output.txt");
{
OutputStream out=new FileOutputStream(file,true);//追加形式
String str="1234abcd";
out.write(str.getBytes(),0,str.length());
String str1="\r\n1234abcd";
out.write(str1.getBytes(),0,str1.length());
out.close();
}
    int len=0;
    byte []buf=new byte[16];
    InputStream in=new FileInputStream(file);
    while((len=in.read(buf))!=-1)
    {
    System.out.print(new String(buf,0,len));
  
}
    in.close(); 
}
}