Java字节流 从文件输入输出到文件过程解析

ch = (char)System.in.read(); //读入一个字符，返回读到的字节的int表示方式,读到末尾返回-1

import java.io.*;
public class 字节流的缓冲区 {
  public static void main(String[] args) throws Exception {
    FileInputStream in=new FileInputStream("E:\\photo\\IMG.jpg");
    //FileOutputStream中的文件不存在，将自动新建文件
    OutputStream out=new FileOutputStream("E:\\test.jpg");
    byte[] buff=new byte[1024];
    int b;
    long beginTime=System.currentTimeMillis();
    while ((b=in.read(buff))!=-1) {
      out.write(buff,0,b);
    }
    long endTime=System.currentTimeMillis();
    System.out.println("运行时长为: "+(endTime-beginTime)+"毫秒");
    in.close();
    out.close();
    System.out.println("正常运行！");
  }
}

//封装了FileOutputStream管道之后，三种函数参数
//write(b) 写入一个b
//write(byte[] b) 将字节数组全部写入
//write(byte[] b,int off,int len) 例如write(byteTest,0,len)表示数组byteTest中从0开始长度为len的字节
//一般都用第3个

import java.io.*;
public class 字节缓冲流 {
  public static void main(String[] args) throws Exception {
    BufferedInputStream bis=new BufferedInputStream(new FileInputStream("E:\\photo\\IMG.jpg"));
    BufferedOutputStream bos=new BufferedOutputStream(new FileOutputStream("E:\\test.jpg"));
    int len;
    long begintime=System.currentTimeMillis();
    while((len=bis.read())!=-1) {
      bos.write(len);
    }
    long endtime=System.currentTimeMillis();
    System.out.println("运行时间为："+(endtime-begintime)+"毫秒");
    bis.close();
    bos.close();
    System.out.println("正常运行");
  }
}

import java.io.*;
public class outFile {
  public static void main(String[] args) throws Exception {
    FileOutputStream out=new FileOutputStream("example.txt");
    String str="测试";
    byte[] b=str.getBytes();
    for(int i=0;i<b.length;i++) {
      out.write(b[i]);
    }
    out.close();
    System.out.println("输出成功");
  }
}

FileOutputStream out=new FileOutputStream("example.txt",true);