IO流，字节流

 /**
  * IO流,字节流
  */
 import java.io.FileInputStream;
 import java.io.FileOutputStream;

 public class ByStreamDemo {
     public static void main(String[] args) throws Exception{
 //        demo_write();
 //        demo_read_1();
         demmo_read_2();
     }
     //写入数据
     public static void demo_write() throws Exception{
         //获取文件
         FileOutputStream fos = new FileOutputStream("F:\\1.txt");
         //写入数据"abcdefg"
         fos.write("abcdefg".getBytes());
         //关闭流
         fos.close();
     }
     //读取数据1
     public static void demo_read_1() throws Exception{
         //获取文件
         FileInputStream fis = new FileInputStream("F:\\1.txt");
         //声明一个数据类型
         int ch = 0;
         //遍历输出
         while((ch = fis.read()) != -1) {
             System.out.print((char) ch);
         }
     }
     //获取数据2
     public static void demmo_read_2() throws Exception{
         //获取文件
         FileInputStream fis = new FileInputStream("F:\\1.txt");
         //声明一个数组
         byte buf[] = new byte[1024];
         //声明一个数据类型
         int len = 0;
         //遍历输出
         while((len = fis.read(buf)) != -1) {
             System.out.println(new String(buf, 0, len));
         }
     }
 }