数组，transferFrom，ByteBuffer数据传输对比

package cache;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.io.RandomAccessFile;import java.nio.ByteBuffer;import java.nio.channels.FileChannel;import java.util.Random;public class CacheTest {public static void main(String args[]) throws IOException {File inFile = new File("f:\\test\\CopyOfBlockCache.java");File outFile = new File("f:\\test\\channel\\"+ (new Random().nextInt()));/* * for (int i = 0; i < 1000; i++) { getOutStream(file); } */InputStream blockIn = getBlockInputStream(inFile);FileChannel fileCh = ((FileInputStream) blockIn).getChannel();if (!outFile.getParentFile().exists())outFile.getParentFile().mkdirs();OutputStream out = getOutStream(outFile);long dataLength = 0;long size = inFile.length();long everLong = 4 * 1024 * 1024;long tmp;long start = System.currentTimeMillis();while (dataLength < size) {tmp = ((FileOutputStream) out).getChannel().transferFrom(fileCh,dataLength, everLong);dataLength += tmp;// System.out.println("dataLength="+dataLength);// System.out.println("everLong="+everLong);// System.out.println("fileSize="+size+",dataLength="+dataLength);}long end = System.currentTimeMillis();// System.out.println("fileSize="+size+",dataLength="+dataLength+",outFile1="+outFile1.length());System.out.println("channel tranfer:" + (end - start));long start1 = System.currentTimeMillis();File outFile1 = new File("f:\\test\\array\\" + (new Random().nextInt()));if (!outFile1.getParentFile().exists())outFile1.getParentFile().mkdirs();read(inFile, outFile1);long end1 = System.currentTimeMillis();System.out.println("array tranfer:" + (end1 - start1));long start2 = System.currentTimeMillis();File outFile2 = new File("f:\\test\\bytebuffer\\"+ (new Random().nextInt()));if (!outFile2.getParentFile().exists())outFile2.getParentFile().mkdirs();readByteBuffer(inFile, outFile2);long end2 = System.currentTimeMillis();System.out.println("readByteBuffer tranfer:" + (end2 - start2));}public static InputStream getBlockInputStream(File srcFile)throws IOException {RandomAccessFile blockInFile;try {blockInFile = new RandomAccessFile(srcFile, "r");} catch (FileNotFoundException fnfe) {throw new IOException("Expected block file at " + srcFile+ " does not exist.");}return new FileInputStream(blockInFile.getFD());}public static OutputStream getOutStream(File targetFile) {FileOutputStream blockOut = null;try {blockOut = new FileOutputStream(new RandomAccessFile(targetFile,"rw").getFD());} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}return blockOut;}public static void read(File srcFile, File desFile) throws IOException {OutputStream out = getOutStream(desFile);InputStream in = getBlockInputStream(srcFile);byte buf[] = new byte[4 * 1024 * 1024];int dataLen = 0;int totalSize = 0;dataLen = in.read(buf, 0, buf.length);while (dataLen != -1) {totalSize += dataLen;out.write(buf, 0, dataLen);dataLen = in.read(buf, 0, buf.length);}}public static void readByteBuffer(File srcFile, File desFile)throws IOException {FileChannel out = ((FileOutputStream) getOutStream(desFile)).getChannel();FileChannel in = ((FileInputStream) getBlockInputStream(srcFile)).getChannel();ByteBuffer buf = ByteBuffer.allocate(4 * 1024 * 1024);while (in.read(buf) != -1) {buf.flip(); // 准备写out.write(buf);buf.clear(); // 准备读}}}

读取4KB小文件：

channel transfer:1
array transfer:9
readByteBuffer transfer:8

读取206MB的大文件：

channel transfer:7118
array transfer:6298
readByteBuffer transfer:12148