FileInputStream inputStream = new FileInputStream("d://vv.mp4");
FileOutputStream outputStream = new FileOutputStream("v.mp4");
int len;
// 一次读取一个字节,每读取一个字节都要实现一次与硬盘的交互操作
while ((len = inputStream.read()) != -1) {
outputStream.write(len);
}
FileInputStream inputStream = new FileInputStream("d://vv.mp4");
FileOutputStream outputStream = new FileOutputStream("v.mp4"); int len;
byte[] bs = new byte[1024];
//这里添加了一个缓存数组,每次从硬盘读取1024个字节,也就是说,每读取1024个字节才与硬盘实现一次交互
while ((len = inputStream.read(bs)) != -1) {
outputStream.write(bs, 0, len);
}
FileInputStream inputStream = new FileInputStream("d://vv.mp4");
BufferedInputStream bis = new BufferedInputStream(inputStream); //默认有8M的缓存
FileOutputStream outputStream = new FileOutputStream("IP.mp4");
BufferedOutputStream bos = new BufferedOutputStream(outputStream);
int len; byte[] bs = new byte[1024]; while ((len = bis.read(bs)) != -1) {
bos.write(bs, 0, len); //先从硬盘读出8M到缓存中。然后read,这里的read并不是从硬盘中读取,而是从那8M缓存(内存)中读取,自然要比从硬盘中快得多。8M缓存用完后又会从硬盘补充(也就是说,一次从硬盘获取8M字节的数据) 。每8M与硬盘交互一次
}

以上三种方式在效率上递增,用BufferedInputStream效率最高(特别是对小文件)。

另外,对于BufferOutputStream和FileOutputStream也是一样,BufferOutputStream的write是把字节写入自带的缓存中(flush之后才向硬盘写),而FileOutputStream则是一次一个字节的向硬盘写。

05-04 01:58