第一種方法:古老的方式

public?static?long?forJava(File?f1,File?f2)?throws?Exception{

long?time=new?Date().getTime();

int?length=2097152;

FileInputStream?in=new?FileInputStream(f1);

FileOutputStream?out=new?FileOutputStream(f2);

byte[]?buffer=new?byte[length];

while(true){

int?ins=in.read(buffer);

if(ins==-1){

in.close();

out.flush();

out.close();

return?new?Date().getTime()-time;

}else

out.write(buffer,0,ins);

}

}

方法的2參數分別是原始文件,和拷貝的目的文件.這里不做過多介紹.

實現方法很簡單,分別對2個文件構建輸入輸出流,并且使用一個字節數組作為我們內存的緩存器, 然后使用流從f1 中讀出數據到緩存里,在將緩存數據寫到f2里面去.這里的緩存是2MB的字節數組

第2種方法:使用NIO中的管道到管道傳輸

public?static?long?forTransfer(File?f1,File?f2)?throws?Exception{

long?time=new?Date().getTime();

int?length=2097152;

FileInputStream?in=new?FileInputStream(f1);

FileOutputStream?out=new?FileOutputStream(f2);

FileChannel?inC=in.getChannel();

FileChannel?outC=out.getChannel();

int?i=0;

while(true){

if(inC.position()==inC.size()){

inC.close();

outC.close();

return?new?Date().getTime()-time;

}

if((inC.size()-inC.position())<20971520)

length=(int)(inC.size()-inC.position());

else

length=20971520;

inC.transferTo(inC.position(),length,outC);

inC.position(inC.position()+length);

i++;

}

}

實現方法:在第一種實現方法基礎上對輸入輸出流獲得其管道,然后分批次的從f1的管道中像f2的管道中輸入數據每次輸入的數據最大為2MB

方法3:內存文件景象寫(讀文件沒有使用文件景象,有興趣的可以回去試試,,我就不試了,估計會更快)

public?static?long?forImage(File?f1,File?f2)?throws?Exception{

long?time=new?Date().getTime();

int?length=2097152;

FileInputStream?in=new?FileInputStream(f1);

RandomAccessFile?out=new?RandomAccessFile(f2,"rw");

FileChannel?inC=in.getChannel();

MappedByteBuffer?outC=null;

MappedByteBuffer?inbuffer=null;

byte[]?b=new?byte[length];

while(true){

if(inC.position()==inC.size()){

inC.close();

outC.force();

out.close();

return?new?Date().getTime()-time;

}

if((inC.size()-inC.position())

length=(int)(inC.size()-inC.position());

}else{

length=20971520;

}

b=new?byte[length];

inbuffer=inC.map(MapMode.READ_ONLY,inC.position(),length);

inbuffer.load();

inbuffer.get(b);

outC=out.getChannel().map(MapMode.READ_WRITE,inC.position(),length);

inC.position(b.length+inC.position());

outC.put(b);

outC.force();

}

}

實現方法:跟傷2個例子不一樣,這里寫文件流沒有使用管道而是使用內存文件映射(假設文件f2在內存中).在循環中從f1的管道中讀取數據到字節數組里,然后在像內存映射的f2文件中寫數據.

第4種方法:管道對管道

public?static?long?forChannel(File?f1,File?f2)?throws?Exception{

long?time=new?Date().getTime();

int?length=2097152;

FileInputStream?in=new?FileInputStream(f1);

FileOutputStream?out=new?FileOutputStream(f2);

FileChannel?inC=in.getChannel();

FileChannel?outC=out.getChannel();

ByteBuffer?b=null;

while(true){

if(inC.position()==inC.size()){

inC.close();

outC.close();

return?new?Date().getTime()-time;

}

if((inC.size()-inC.position())

length=(int)(inC.size()-inC.position());

}else

length=2097152;

b=ByteBuffer.allocateDirect(length);

inC.read(b);

b.flip();

outC.write(b);

outC.force(false);

}

}

這里實現方式與第3種實現方式很類似,不過沒有使用內存影射.

下面是對49.3MB的文件進行拷貝的測試時間(毫秒)

Start Copy File... ?file size:50290KB

CopyFile:b1.rmvb mode:forChannel ?RunTime:3203

CopyFile:b1.rmvb mode:forImage ?RunTime:3328

CopyFile:b1.rmvb mode:forJava ?RunTime:2172

CopyFile:b1.rmvb mode:forTransfer RunTime:1406

End Copy File!