import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;import java.io.LineNumberReader;import java.nio.Buffer;public class io {	public static void main(String[] args) throws IOException	{		writeFile();		readFile1();		readFile2();	}	//写入	public static void writeFile() throws IOException	{		FileOutputStream fos = new FileOutputStream("fos.txt");		fos.write("abcd".getBytes());		fos.close();	}		//读出	public static void readFile1() throws IOException	{		FileInputStream fis1 = new FileInputStream("fos.txt");		int ch=0;		while((ch=fis1.read())!=-1) //一个一个读		{			System.out.println((char)ch);		}		fis1.close();	}		public static void readFile2() throws IOException	{		FileInputStream fis2 = new FileInputStream("fos.txt");		byte[] buf = new byte[1024]; //缓冲区		int len = 0;		while((len=fis2.read(buf))!=-1) //以数组大小读入  返回值是读入的个数		{			System.out.println(new String (buf,0,len));		}		fis2.close();				FileInputStream fis3 = new FileInputStream("fos.txt");		//fis2.available 文件中字节的个数 		int num = fis3.available();		//定义一个刚刚好的缓冲区，不能用与文件很大的 和爆内存		byte[] buf2 = new byte[fis3.available()];		fis3.read(buf2);		System.out.println(num+":"+new String(buf2));		fis3.close();	}}