Java字节缓冲流原理与用法详解

/**
 * 进行文件的拷贝，利用带缓冲的字节流
 * @param srcFile
 * @param destFile
 * @throws IOException
 */
public static void copyFileByBuffer(File srcFile,File destFile)throws IOException{
    if(!srcFile.exists()){
        throw new IllegalArgumentException("文件:"+srcFile+"不存在");
    }
    if(!srcFile.isFile()){
        throw new IllegalArgumentException(srcFile+"不是文件");
    }
    BufferedInputStream bis = new BufferedInputStream(
            new FileInputStream(srcFile));
    BufferedOutputStream bos = new BufferedOutputStream(
            new FileOutputStream(destFile));
    int c ;
    while((c = bis.read())!=-1){
        bos.write(c);
        bos.flush();//刷新缓冲区
    }
    bis.close();
    bos.close();
}

/**
 * 单字节，不带缓冲进行文件拷贝
 * @param srcFile
 * @param destFile
 * @throws IOException
 */
public static void copyFileByByte(File srcFile,File destFile)throws IOException{
    if(!srcFile.exists()){
        throw new IllegalArgumentException("文件:"+srcFile+"不存在");
    }
    if(!srcFile.isFile()){
        throw new IllegalArgumentException(srcFile+"不是文件");
    }
    FileInputStream in = new FileInputStream(srcFile);
    FileOutputStream out = new FileOutputStream(destFile);
    int c ;
    while((c = in.read())!=-1){
        out.write(c);
        out.flush();
    }
    in.close();
    out.close();
}

package com.imooc.io;
import java.io.File;
import java.io.IOException;
public class IOUtilTest4 {
    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        try {
            long start = System.currentTimeMillis();
            IOUtil.copyFileByByte(new File("e:\\javaio\\demo.mp3"), new File(
                    "e:\\javaio\\demo2.mp3")); //两万多毫秒
            long end = System.currentTimeMillis();
            System.out.println(end - start );
            start = System.currentTimeMillis();
            IOUtil.copyFileByBuffer(new File("e:\\javaio\\demo.mp3"), new File(
                    "e:\\javaio\\demo3.mp3"));//一万多毫秒
            end = System.currentTimeMillis();
            System.out.println(end - start );
            start = System.currentTimeMillis();
            IOUtil.copyFile(new File("e:\\javaio\\demo.mp3"), new File(
                    "e:\\javaio\\demo4.mp3"));//7毫秒
            end = System.currentTimeMillis();
            System.out.println(end - start );
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}