IO流学习笔记

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/athur666/article/details/78232555

什么是流
流是一组有序的，有起点和终点的字节集合，是对计算机中数据传输的总称或者抽象
即数据在两个设备间的传输称为流，流的本质是数据传输。

流序列中的数据可以是没有进行加工的原始数据（二进制字节数据），也可以是经过编码的符合某种格式规定的数据，Java中提供了不同的流类对它们进行处理。

流按照传输方向可以分为                                          按照传输方式可以分为

输入流  用于读取数据    含有Input                            字节流    含有stream

输出流  用于写入数据  含有Output                           字符流    不含stream

import java.io.*;
 
public class ExampleIo {
    public static void main(String[] args)throws Exception {
        new ExampleIo().bufferReaderWriter();
    }
 
    //字节流读取文件
    public void zifuliuReader() throws Exception{
        File ff=new File("E:\\today.txt");
        FileInputStream in =new FileInputStream(ff);
        int xx=0;
        String   value="";
        while ((xx=in.read())!=-1){
            System.out.print((char) xx);
            value+=(char)xx;
        }
        in.close();
    }
 
    //字符流读取文件
    public void zijieReader()throws Exception{
        File ff=new File("E:\\today.txt");
        int xx=0;
        FileReader rd=new FileReader(ff);
        while ((xx=rd.read())!=-1){
            System.out.print((char)xx);
        }
        rd.close();
    }
    //字节流读取
        byte[] ss= new String("goodluck").getBytes();
     ByteArrayInputStream by= new ByteArrayInputStream(ss);
        byte[] bs=new byte[1024];
        int len=0;
      while ((len=by.read(bs))!=-1){
          System.out.println(new String(bs,0,len));
      }
    //字节流写入文件
    public  void zijieWriter()throws Exception{
        File ff=new File("E:\\today.txt");
        OutputStream out=new FileOutputStream(ff);
        String zz="today is a good day";
        byte[] b=zz.getBytes();
        InputStream  io2=new ByteArrayInputStream(b);
        byte[] bs=new byte[1024];
        int len=0;
        while ((len=io2.read(bs))!=-1){
            out.write(bs,0,len);
        }
        io2.close();
        out.close();
    }
    //字符流写入文件
    public void zifuWriter()throws Exception{
        File ff=new File("E:\\today.txt");
        FileWriter writer=new FileWriter(ff);
        writer.write("今天是个好日子");
        writer.close();
    }
 
    //字符流转换字节流的桥梁  可使用指定的 charset 将要写入流中的字符编码成字节。
    public void TranferToZiJie()throws Exception{
        File ff=new File("E:\\today.txt");
        FileOutputStream out=new FileOutputStream(ff);
        OutputStreamWriter writer=new OutputStreamWriter(out,"utf-8");
        writer.write("今天是个好日子");
        writer.close();
 
    }
    //将字节流向字符流的转换
    public void TranferToZiFu()throws Exception{
 
        File ff=new File("E:\\today.txt");
        InputStreamReader in=new InputStreamReader(new FileInputStream(ff),"utf-8");
        char[] b=new char[1024];
        int s=in.read(b);
        System.out.println(new String(b,0,s));
        in.close();
 
    }
    //利用缓冲区读写文件
 
    public  void bufferReaderWriter()throws  Exception{
 
        File ff=new File("E:\\today.txt");
 
        InputStreamReader in=new InputStreamReader(new FileInputStream(ff),"utf-8");
        BufferedReader rd=new BufferedReader(in);
        String value="";
        while ((value=rd.readLine())!=null){
            System.out.println(value);
        }
        rd.close();
 
        OutputStreamWriter writer=new OutputStreamWriter(new FileOutputStream(ff),"utf-8");
 
        BufferedWriter bf=new BufferedWriter(writer);
        bf.write("今天是个好日子");
        bf.close();
    }
}