IO、字节流File读取操作

package CoreJavaPractice;
import java.io.*;
public class Practice_1 {
        public static void main(String[] args) throws IOException  {
        
            readFile_3();
            
            
        }
        public static void readFile_3() throws IOException
        {
            FileInputStream fis = new FileInputStream("FileStreamDemo.txt");
            
            byte[] buf = new byte[fis.available()];
            fis.read(buf);
            System.out.println(new String(buf));
            fis.close();
        }
        
        
        public static void readFile_2() throws IOException
        {
            FileInputStream fis = new FileInputStream("FileStreamDemo.txt");
            byte[] buf = new byte[1024];
            int len = 0;
            while((len=fis.read(buf))!=-1)
            {
                System.out.println(new String(buf,0,len));
            }
            fis.close();
        }
        
        public static void readFile_1() throws IOException
        {
            FileInputStream fis = new FileInputStream("FileStreamDemo.txt");
            int ch = 0;
            while((ch=fis.read())!=-1)
            {
                System.out.println((char)ch);
            }
            fis.close();
        }
        public static void writeFile() throws IOException
        {
            FileOutputStream fos = new FileOutputStream("FileStreamDemo.txt");
            
            fos.write("abcde".getBytes());
            
            fos.close();
        }

}