Java IO与NIO来Copy文件的四种方法实现以及性能对比

使用Java的IO与NIO来Copy文件的四种方法实现以及性能对比

FileCopyRunner接口，定义了Copy文件的接口，等下在测试类中使用匿名内部类来实现。

package nio.channel;

import java.io.File;

public interface FileCopyRunner {
    void copyFile(File source , File target);
}

测试类：

• benchmark()：Copy文件ROUNDS（5）次，并且返回耗费的平均时间(1.0F)*elapsed / ROUNDS。
• close()：关闭资源。

完整代码（下面说四种方法）：

package nio.channel;

import java.io.*;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

public class FileCopyDemo {

    private static final int ROUNDS = 5;

    private static void benchmark(FileCopyRunner test ,
                                  File sourse , File target){
        long elapsed = 0L;
        for (int i = 0; i < ROUNDS; i++) {
            long startTime = System.currentTimeMillis();
            test.copyFile(sourse , target);
            elapsed += System.currentTimeMillis() - startTime;
            target.delete();
        }
        System.out.println(test+"："+(1.0F)*elapsed / ROUNDS);
    }

    public static void close(Closeable closeable){
        if(closeable != null){
            try {
                closeable.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) {
        FileCopyRunner noBufferStreamCopy  = new FileCopyRunner() {
            @Override
            public void copyFile(File sourse, File target) {
                InputStream fin = null;
                OutputStream fout = null;
                try {
                    fin = new FileInputStream(sourse);
                    fout = new FileOutputStream(target);

                    int result;
                    while((result = fin.read()) != -1){
                        fout.write(result);
                    }
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                } finally{
                    close(fin);
                    close(fout);
                }
            }

            @Override
            public String toString() {
                return "noBufferStreamCopy";
            }
        };

        FileCopyRunner bufferedStreamCopy = new FileCopyRunner() {
            @Override
            public void copyFile(File sourse, File target) {
                InputStream fin = null;
                OutputStream fout = null;
                try {
                    fin = new BufferedInputStream(new FileInputStream(sourse));
                    fout = new BufferedOutputStream(new FileOutputStream(target));

                    byte[] buffer = new byte[8192];

                    int result;
                    while((result = fin.read(buffer)) != -1){
                        fout.write(buffer , 0 ,result);
                    }
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                } finally{
                    close(fin);
                    close(fout);
                }
            }

            @Override
            publ