常用文件复制方法

1、文件字节流

package com.java.copyFile;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;public class CopyByInputStreamAndOutputStream {public static void main(String[] args) {long time1=System.currentTimeMillis();//File source=new File("E:\\Java编程思想 第四版习题答案.pdf");//File target=new File("F:\\Java编程思想 第四版习题答案.a");File source=new File("F:\\迅雷下载\\[电影天堂-www.dy2018.net]霸王别姬BD国语中字.rmvb");File target=new File("E:\\Java编程思想 第四版习题答案.a");try {Copy( source, target);} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}long time2=System.currentTimeMillis();System.out.println(time2-time1);}public static void Copy(File source,File target) throws IOException{if(target.exists())target.delete();FileInputStream  fis=new FileInputStream(source);FileOutputStream fos=new FileOutputStream(target);byte bys[]=new byte[1024];int len=0;while((len=fis.read(bys))!=-1)fos.write(bys);fis.close();fos.close();}}

2、字节缓冲流

package com.java.copyFile;import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;public class CopyByBufferInputStreamAndBufferOutPutStream {public static void main(String[] args) {long time1=System.currentTimeMillis();File source=new File("F:\\迅雷下载\\[电影天堂-www.dy2018.net]霸王别姬BD国语中字.rmvb");File target=new File("E:\\Java编程思想 第四版习题答案.a");try {Copy( source, target);} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}long time2=System.currentTimeMillis();System.out.println(time2-time1);}private static void Copy(File source, File target) throws IOException {if(target.exists())target.delete();FileInputStream fis=new FileInputStream(source);BufferedInputStream bis=new BufferedInputStream(fis);FileOutputStream fos=new FileOutputStream(target);BufferedOutputStream bos=new BufferedOutputStream(fos);int len=0;StringBuffer buufar=new StringBuffer();byte by[]=new byte[1024];while((len=bis.read(by))!=-1)bos.write(by);bos.flush();bis.close();bos.close();}}

3、字符流

package com.java.copyFile;import java.io.File;import java.io.FileNotFoundException;import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;public class CopyByFileReaderAndFileWriter {public static void main(String[] args) {long time1=System.currentTimeMillis();File source=new File("E:\\Java编程思想 第四版习题答案.pdf");File target=new File("F:\\Java编程思想 第四版习题答案.a");try {Copy( source, target);} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}long time2=System.currentTimeMillis();System.out.println(time2-time1);}private static void Copy(File source, File target) throws IOException {if(target.exists())target.delete();FileReader fr=new FileReader(source);FileWriter fw=new FileWriter(target);char c[]=new char[1024];int len=0;while((len=fr.read(c))!=-1)fw.write(c);fr.close();fw.close();}}

4、字符缓冲流

package com.java.copyFile;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.File;import java.io.FileNotFoundException;import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;public class CopyByBufferReaderAndBufferWriter {public static void main(String[] args) {long time1=System.currentTimeMillis();File source=new File("E:\\Java编程思想 第四版习题答案.pdf");File target=new File("F:\\Java编程思想 第四版习题答案.a");try {Copy( source, target);} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}long time2=System.currentTimeMillis();System.out.println(time2-time1);}private static void Copy(File source, File target) throws IOException {if(target.exists())target.delete();FileReader fr=new FileReader(source);BufferedReader br=new BufferedReader(fr);FileWriter fw=new FileWriter(target);BufferedWriter bw=new BufferedWriter(fw);String s=null; StringBuffer buffer=new StringBuffer();while((s=br.readLine())!=null){buffer.append(s);}bw.write(new String(buffer));bw.flush();br.close();bw.close();}}

5、单线程Channel

package com.java.copyFile;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.nio.channels.FileChannel;import java.nio.channels.WritableByteChannel;public class CopyByFileChannel {public static void main(String[] args) {long time1=System.currentTimeMillis();//File source=new File("E:\\Java编程思想 第四版习题答案.pdf");//File target=new File("F:\\Java编程思想 第四版习题答案.a");File source=new File("F:\\迅雷下载\\[电影天堂-www.dy2018.net]霸王别姬BD国语中字.rmvb");File target=new File("E:\\Java编程思想 第四版习题答案.a");try {Copy( source, target);} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}long time2=System.currentTimeMillis();System.out.println(time2-time1);}private static void Copy(File source, File target) throws IOException {if(target.exists())target.delete();FileInputStream fis=new FileInputStream(source);FileOutputStream fos=new FileOutputStream(target);//input流调用方法getChannel()获得一个连接到底层文件的FileChannei对象(信道)FileChannel fileChannel=fis.getChannel();//WritableByetChannel(接口)可写入的字节通道WritableByteChannel writableByteChannel=fos.getChannel();//将字节从此通道的文件传输到给定的可写入字节通道。fileChannel.transferTo(0, fileChannel.size(), writableByteChannel);writableByteChannel.close();fileChannel.close();fos.close();fis.close();}}

6、多线程channel

package com.java.copyFile;import java.io.File;import java.io.FileNotFoundException;import java.io.IOException;import java.io.RandomAccessFile;import java.nio.channels.FileChannel;import java.nio.channels.FileLock;public class CopyFileThread extends Thread {private File source;private File target;private long start,end;public CopyFileThread(File source, File target, long start, long end) {this.source = source;this.target = target;this.start = start;this.end = end;}@Overridepublic void run() {long starttime=System.currentTimeMillis();try {RandomAccessFile in=new RandomAccessFile(source, "r");RandomAccessFile out=new RandomAccessFile(target, "rw");in.seek(start);out.seek(start);FileChannel inChannel=in.getChannel();FileChannel outChanel=out.getChannel();//在可以锁定该区域、已关闭此通道或者已中断调用线程（以先到者为准）之前，将阻塞此方法的调用FileLock lock=outChanel.lock(start, (end-start), false);//试图读取从此通道的文件中给定 position 处开始的 count 个字节，并将其写入目标通道inChannel.transferTo(start, end-start, outChanel);lock.release();in.close();out.close();} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}long endtime=System.currentTimeMillis();System.out.println(Thread.currentThread().getName()+"  用时 "+(endtime-starttime));}}

package com.java.copyFile;import java.io.File;public class Test {private  static int blockcount=1;public static void main(String[] args) {File source=new File("F:\\迅雷下载\\[电影天堂-www.dy2018.net]霸王别姬BD国语中字.rmvb");File target=new File("E:\\Java编程思想 第四版习题答案.a");if(target.exists())target.delete();long len=source.length();long oneNum=len/blockcount;for(int i=0;i<blockcount-1;i++)new CopyFileThread(source, target, oneNum*i, oneNum*(i+1)).start();new CopyFileThread(source, target, oneNum*(blockcount-1), len).start();}}