Java IO系列之字节流拷贝文件性能比较

Java IO 字节流基类

InputStream--输入流，

OutPutStream--输出流，

输入流用于读，输出流用于写.

字节流默认一次只读取或输出一个字节。

package jonavin.io;import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;public class IOUtil {/*** 文件拷贝-- 一个字节一个字节拷贝* @param srcFile* @param destFile*/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);//源文件FileOutputStream out = new FileOutputStream(destFile);//目标文件int b;while ((b = in.read()) != -1) {out.write(b);//写入一个字节的低八位
        }in.close();out.close();}/*** 拷贝文件一次读取多个字节*/public static void copyFileByByteBuf(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);//源文件FileOutputStream out = new FileOutputStream(destFile);//目标文件int b;byte[] buf = new byte[8*1024];//开辟8K的缓存while ((b = in.read(buf,0,buf.length))!=-1) {out.write(buf, 0, b);}in.close();out.close();}/*** 通过缓冲流copy文件* @throws IOException*/public static void copyFileByBuffed(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);//源文件FileOutputStream out = new FileOutputStream(destFile);//目标文件BufferedInputStream inbuf = new BufferedInputStream(in);BufferedOutputStream outbuf = new BufferedOutputStream(out);int b;while ((b = inbuf.read())!=-1) {outbuf.write(b);}in.close();out.close();inbuf.close();outbuf.close();}/*** 通过缓冲流copy文件 缓冲流一次读取多个字节* @throws IOException*/public static void copyFileByBuffedBuf(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);//源文件FileOutputStream out = new FileOutputStream(destFile);//目标文件BufferedInputStream inbuf = new BufferedInputStream(in);BufferedOutputStream outbuf = new BufferedOutputStream(out);int b;byte[] buf = new byte[8*1024];while ((b = inbuf.read(buf,0,buf.length))!=-1) {outbuf.write(buf,0,b);}in.close();out.close();inbuf.close();outbuf.close();}/*** 文件拷贝* @param srcpath* @param destpath* @throws IOException*/public static void copyFile(String srcpath,String destpath)throws IOException{copyFileByBuffedBuf(new File(srcpath), new File(destpath));}
}

调用 ： IOUtil.copyFile("C:\\apache-tomcat-7.0.57.zip", "c:\\ret.dat");//源文件大小9M

copyFileByByte  ----》 62229 毫秒

copyFileByByteBuf -----》 97 毫秒

copyFileByBuffed -----》 457 毫秒

copyFileByBuffedBuf ----》 28 毫秒  效率最好