Java--stream,nio Bytebuffer,nio Mappedbytebuffer Performance Comparison

At present, the most IO in Java has a variety of file reading methods, this article compares the performance of Stream,nio Bytebuffer,nio Mappedbytebuffer, let us know how to write high performance file read code.

 PackageCom.seeyon.nio;Importorg.junit.Test;ImportJava.io.*;ImportJava.nio.ByteBuffer;ImportJava.nio.MappedByteBuffer;ImportJava.nio.channels.FileChannel;/*** Created by Yangyu on 16/12/28.*//*** Compare Stream stream, NiO Bytebuffer,nio mappedbytebuffer performance comparison * with stream slowest, NiO mappedbytebuffer fastest * stream:1000ms * NiO bytebuf fer:220ms * NIO mappedbytebuffer:112ms*/ Public classCompare {/*** Read and write files using stream as IO stream * Speed: Around 1000ms * *@throwsIOException*/@Test Public voidUsestream ()throwsIOException {LongStartTime =System.currenttimemillis (); /*** 4 million integer-length files*/        intnum = 2000 * 2000; /*** Buffered output stream, write file*/DataOutputStream DataOutputStream=NewDataOutputStream (NewBufferedoutputstream (NewFileOutputStream ("/users/yangyu/downloads/compare.tmp")));  for(inti = 0; i < num; i++) {dataoutputstream.writeint (i);        } dataoutputstream.close (); intdata = 0; /*** Buffered input stream, read file*/DataInputStream in=NewDataInputStream (NewBufferedinputstream (NewFileInputStream ("/users/yangyu/downloads/compare.tmp"))); Try {             while(true) {Data=In.readint (); }        } Catch(eofexception e) {System.out.println ("Read Complete" +data);        } in.close (); LongEndTime =System.currenttimemillis (); System.out.println ("MS:" + (EndTime-startTime)); }    /*** Using NiO Bytebuffer * Time: 220ms *@throwsIOException*/@Test Public voidUseniobytebuffer ()throwsIOException {LongStartTime =System.currenttimemillis (); intnum = 2000*2000; /*** File output stream*/FileOutputStream FileOutputStream=NewFileOutputStream ("/users/yangyu/downloads/compare.tmp"); /*** NIO Channel channels*/FileChannel FileChannel=Fileoutputstream.getchannel (); /*** Bytebuffer Buffer*/Bytebuffer Buffer= Bytebuffer.allocate (num*5);  for(inti = 0; i < num; i++) {buffer.putint (i); }        /*** Prepare for writing*/Buffer.flip (); /*** Write Operation*/filechannel.write (buffer);        Filechannel.close (); /*** Buffer*/Bytebuffer Buffer1= Bytebuffer.allocate (num*5); /*** File input stream*/FileInputStream in=NewFileInputStream ("/users/yangyu/downloads/compare.tmp"); /*** Input Channel*/filechannel Fin=In.getchannel (); /*** Prepare for reading*/buffer1.clear ();        System.out.println (Buffer1.limit ()); /*** Read*/Fin.read (Buffer1);        Fin.close (); LongEndTime =System.currenttimemillis (); System.out.println ("MS:" + (EndTime-startTime));        Buffer1.flip ();    System.out.println (Buffer1.limit ()); }    /*** Use Mappedbytebuffer to map files to memory by FileChannel * Time: 112ms *@throwsIOException*/@Test Public voidUserandomaccess ()throwsIOException {LongStartTime =System.currenttimemillis (); intnum = 2000*2000; /*** Use Randomaccessfile with a random access location*/randomaccessfile File=NewRandomaccessfile ("/users/yangyu/downloads/compare.tmp", "RW"); /*** Get channel channels*/FileChannel FileChannel=File.getchannel (); /*** Map files to buffers Mappedbytebuffer*/Mappedbytebuffer Mappedbytebuffer= Filechannel.map (filechannel.mapmode.read_write,0,num*4); /*** Write Files*/         for(inti = 0; i < num; i++) {mappedbytebuffer.putint (i);        } filechannel.close (); intData=0; Randomaccessfile file1=NewRandomaccessfile ("/users/yangyu/downloads/compare.tmp", "RW"); FileChannel FC=File1.getchannel (); Mappedbytebuffer MappedByteBuffer1= Fc.map (filechannel.mapmode.read_write,0, File1.length ()); /*** Read File*/         while(Mappedbytebuffer1.hasremaining ()) {Data=Mappedbytebuffer1.getint ();        } fc.close (); LongEndTime =System.currenttimemillis (); System.out.println ("MS:" + (EndTime-startTime));    SYSTEM.OUT.PRINTLN (data); }}

The conclusion is very obvious, when using IO to read and write files later, use NiO mappedbytebuffer, after all, NiO is much better than the old IO performance.

Java--stream,nio Bytebuffer,nio Mappedbytebuffer Performance Comparison