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