采用Java语言如何实现高速文件复制？

今天review代码也看到了“大神”用老方法来实现文件拷贝。今天归结一下使用Java语言怎样实现高速文件复制：

代码1——使用文件通道的方式：

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;

public class Test {
	public static void main(String[] args){
		long start = System.currentTimeMillis();
		FileInputStream fileInputStream = null;
        FileOutputStream fileOutputStream = null;
        FileChannel inFileChannel = null;
        FileChannel outFileChannel = null;
        try {
        	fileInputStream = new FileInputStream(new File("C:\\from\\不是闹着玩的.flv"));
        	fileOutputStream = new FileOutputStream(new File("C:\\to\\不是闹着玩的.flv"));
            inFileChannel = fileInputStream.getChannel();
            outFileChannel = fileOutputStream.getChannel();
            inFileChannel.transferTo(0, inFileChannel.size(), outFileChannel);//连接两个通道。从in通道读取数据写入out通道。

} catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
            	if(fileInputStream != null){
            		fileInputStream.close();
            	}
            	if(inFileChannel != null){
	                inFileChannel.close();
            	}
                if(fileOutputStream != null){
	                fileOutputStream.close();
                }
                if(outFileChannel != null){
	                outFileChannel.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
		long end = System.currentTimeMillis();
		System.out.println("视频文件从“from”目录拷贝到“to”文件须要" + (end - start) + "毫秒。

");
	}
}

代码执行结果为：

代码2——使用缓冲输入输出流

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class Test {
	public static void main(String[] args){
		long start = System.currentTimeMillis();
		InputStream fileInputStream = null;
        OutputStream fileOutputStream = null;
        try {
        	fileInputStream = new BufferedInputStream( new FileInputStream(new File("C:\\from\\不是闹着玩的.flv")));
        	fileOutputStream = new BufferedOutputStream(new FileOutputStream(new File("C:\\to\\不是闹着玩的.flv")));
        	byte[] bufferArray = new byte[1024*1024];
            int length;
            while ((length = fileInputStream.read(bufferArray)) != -1) {
                fileOutputStream.write(bufferArray, 0, length);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
            	if(fileInputStream != null){
            		fileInputStream.close();
            	}
                if(fileOutputStream != null){
	                fileOutputStream.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
		long end = System.currentTimeMillis();
		System.out.println("视频文件从“from”目录拷贝到“to”文件须要" + (end - start) + "毫秒。");
	}
}

代码执行结果为：
  

代码3——使用文件输入输出流的方式：

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class Test {
	public static void main(String[] args){
		long start = System.currentTimeMillis();
		FileInputStream fileInputStream = null;
		FileOutputStream fileOutputStream = null;
		try{
			fileInputStream = new FileInputStream(new File("C:\\from\\不是闹着玩的.flv")); //读入原文件
			fileOutputStream = new FileOutputStream("C:\\to\\不是闹着玩的.flv");
	       	byte[] bufferArray = new byte[1024*1024];
	       	int length;
	       	while ((length = fileInputStream.read(bufferArray)) != -1) {
	       		fileOutputStream.write(bufferArray, 0, length);
	       	}
		} catch (IOException e) {
            e.printStackTrace();
        } finally {
        	try {
        		if(fileInputStream != null){
        			fileInputStream.close();
        		}
        		if(fileOutputStream != null){
        			fileOutputStream.close();
        		}
			} catch (IOException e) {
				e.printStackTrace();
			}
        }
		long end = System.currentTimeMillis();
		System.out.println("视频文件从“from”目录拷贝到“to”文件须要" + (end - start) + "毫秒。");
	}
}

代码执行结果为：

代码1、代码2和代码3复制的是同样的文件，通过对比不难得出结论：：尝试使用文件时，文件拷贝输入和输出流可能是一个更好的办法。

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