字节流File读写操作

/*
字节流
InputStream OutputStream
不需要进行flush
操作图片数据需要用到字节流*/import java.io.*;class FileStream{public static void main(String[] args)throws IOException{// writeFile();readFile_3();}public static void readFile_1()throws IOException{FileInputStream fis=new FileInputStream("fos.txt");int ch=0;while((ch=fis.read())!=-1){System.out.println((char)ch);}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_3()throws IOException{   //字节流特有方法FileInputStream fis=new FileInputStream("fos.txt");int num=fis.available();byte[]buf=new byte[num];//定义一个刚刚好的缓冲区，不用再循环fis.read(buf);System.out.println(new String(buf));fis.close();}public static void writeFile()throws IOException{FileOutputStream fos=new FileOutputStream("fos.txt");fos.write("abcde".getBytes());fos.close();}}

读写图片

/*
拷贝图片
1.用字节读取流对象和图片关联
2.用字节写入流对象创建一个图片文件，用于储存
3.循环读写
4.关闭资源*/import java.io.*;class CopyPic{public static void main(String[] args){FileOutputStream fos=null;FileInputStream fis=null;try{fos=new FileOutputStream("xx.bmp");fis=new FileInputStream("oo.bmp");byte[]buf=new byte[1024];int len=0;while((len=fis.read(buf))!=-1){fos.write(buf,0,len);}}catch(IOException e){throw new RuntimeException("Wrong!");}finally{try{if(fis!=null){fis.close();}}catch(IOException e){throw new RuntimeException("ooWrong!");}try{if(fos!=null){fos.close();}}catch(IOException e){throw new RuntimeException("xxWrong!");}}}}

字节流缓冲区

/*
BufferedOutputStream
BufferedInputStream*/
import java.io.*;
class CopyMp3{public static void main(String[] args)throws IOException{long start=System.currentTimeMillis();copy_1();long end=System.currentTimeMillis();System.out.pringln((end-start));}public static void copy_1()throws IOException{BufferedInputStream bufis=new BufferedInputStream(new FileInputStream("xx.mp3"));BufferedOutputStream bufos=new BufferedOutputStream(new FileOutputStream("oo.mp3"));int by=0;while((by=bufis.read())!=-1){bufos.write(by);}bufos.close();bufis.close();}
}

自定义字节流缓冲区

import java.io.*;
class MyBufferedInputStream{private InputStream in;private byte[]buf=new byte[1024];private int pos=0,count=0;MyBufferedInputStream(InputStream in){this.in=in;}// 一次读一个字节，从缓冲区获取public int myRead()throws IOException{// 通多in对象读取硬盘上数据并存储至bufif(count==0){count-in.read(buf);pos=0;//每一次pos需要归0byte b=buf[pos];count--;pos++;return b;}else if(count>0){byte b=buf[pos];count--;pos++;return b&0xff;//防止初始count为-1}return -1;}public void myColse()throws IOException{in.close();}
}