IO流(字节流File读写操作)

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字符流：

FileReader

FileWriter

BufferedReader

BufferedWriter

字节流：

InputStream OutputStream

需求，想要操作图片数据。这时就要用到字节流。

import java.io.*; class FileStream{    public static void main(String[] args)throws IOException    {        readFile_3();    }         public static void readFile_3()throws IOException    {        FileInputStream fis = new FileInputStream("fos.txt");                 // int num = fis.available();        byte[] buf = new byte[fis.available()];//定义一个刚刚好的缓冲区。不用再循环了                 fis.read(buf);                 // System.out.println("num="+num);        System.out.println(new String(buf));                 fis.close();    }         public static void readFile_2()throws IOException    {        FileInputStream fis = new FileInputStream("fos.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("fos.txt");    }    public static void writeFile()throws IOException    {        FileOutputStream fos = new FileOutputStream("fos.txt");                 fos.write("abcde".getBytes());    }}

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