Driect-nonDricect 读取文件速度

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fos.write() 7965 ms

fileChannel.transferTo 170 ms

MappedByteBuffer out = fc.map(FileChannel.MapMode.READ_WRITE, 0, length);  raf = new RandomAccessFile( metaFile, "rw" );FileChannel channel = raf.getChannel();channel.force( true );//強制將所有對此通道的檔案更新寫入包含該檔案的存儲設備中。如果此通道的檔案駐留在本地存儲設備上，則此方法返回時可保證,否则不保证。MappedByteBuffer buf = channel.map( FileChannel.MapMode.READ_WRITE, 0, metadataMaxLenght );

import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.RandomAccessFile;import java.nio.channels.FileChannel;public class TestFileChannel {    public static void main( String[] args ) throws Exception {            }        public static void a() throws Exception{        File file = new File("d:/bcw-200.log");        FileInputStream fis = new FileInputStream( file );        File outFile = new File("d:/bcw-201.log");        FileOutputStream fos = new FileOutputStream( outFile );        int byteToRead = 1024;        byte[] buff = new byte[byteToRead];//        int byteRead = 0;//        while(true){//            int result = fis.read( bb, byteRead, byteToRead - byteRead );//            if(result==-1){//                break;//            }//            byteRead += result;//        }        long start = System.currentTimeMillis();        while(true){            int result = fis.read( buff );            fos.write( buff );            if(result == -1){                break;            }        }        System.out.println(System.currentTimeMillis() - start);        fis.close();        fos.close();        System.out.println(System.currentTimeMillis() - start);    }        public static void b() throws Exception{        File file = new File("d:/bcw-200.log");        FileInputStream fis = new FileInputStream( file );        File outFile = new File("d:/bcw-202.log");        FileOutputStream fos = new FileOutputStream( outFile );        FileChannel in = fis.getChannel();        FileChannel out = fos.getChannel();        long start = System.currentTimeMillis();        in.transferTo( 0, file.length(), out );        System.out.println(System.currentTimeMillis() - start);        in.close();        out.close();        System.out.println(System.currentTimeMillis() - start);    }        public static void c() throws Exception{        File file = new File("d:/bcw-200.log");        FileInputStream fis = new FileInputStream( file );        File outFile = new File("d:/bcw-202.log");        FileOutputStream fos = new FileOutputStream( outFile );        FileChannel in = fis.getChannel();        FileChannel out = fos.getChannel();        RandomAccessFile raf = new RandomAccessFile( file, "rw" );               long start = System.currentTimeMillis();        in.transferTo( 0, file.length(), out );        System.out.println(System.currentTimeMillis() - start);        in.close();        out.close();        System.out.println(System.currentTimeMillis() - start);    }}

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