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JeffLi1993JeffLi1993
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新增：MappedByteBuffer与Old IO的性能比
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‎src/org/javacore/nio/MappedIO.java‎

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package org.javacore.nio;
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import org.javacore.io.RandomAccessFileT;
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import java.io.BufferedInputStream;
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import java.io.BufferedOutputStream;
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import java.io.DataInputStream;
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import java.io.DataOutputStream;
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import java.io.File;
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import java.io.FileInputStream;
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import java.io.FileOutputStream;
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import java.io.IOException;
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import java.io.RandomAccessFile;
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import java.nio.IntBuffer;
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import java.nio.channels.FileChannel;
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/*
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* Copyright [2015] [Jeff Lee]
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/**
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* @author Jeff Lee
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* @since 2015-10-15 18:38:17
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* MappedByteBuffer与Old IO的性能比
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*/
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public class MappedIO {
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private static int numOfInts = 4000000;
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private static int numOfUbuffInts = 200000;
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private abstract static class Tester {
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private String name;
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public Tester(String name){
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this.name = name;
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}
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// 打印测试时间
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public void runTests(){
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System.out.print(name + ": ");
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try {
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long start = System.nanoTime();
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test();
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double duration = System.nanoTime() - start;
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System.out.format("%.2f\n",duration/1.0e9);
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} catch (IOException e) {
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throw new RuntimeException(e);
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}
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}
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public abstract void test() throws IOException;
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}
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private static Tester[] tests = {
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new Tester("Stream Write") {
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@Override
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public void test() throws IOException {
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DataOutputStream dos = new DataOutputStream(
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new BufferedOutputStream(new FileOutputStream(new File("data.txt"))));
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for (int i = 0; i < numOfInts; i++)
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dos.writeInt(i);
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dos.close();
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}
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},
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new Tester("Mapped Write") {
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@Override
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public void test() throws IOException {
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FileChannel fc =
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new RandomAccessFile("data.txt" , "rw").getChannel();
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IntBuffer ib = fc.map(FileChannel.MapMode.READ_WRITE,
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0,fc.size()).asIntBuffer();
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for (int i = 0; i < numOfInts; i++)
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ib.put(i);
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fc.close();
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}
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},
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new Tester("Stream Read") {
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@Override
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public void test() throws IOException {
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DataInputStream dis = new DataInputStream(
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new BufferedInputStream(new FileInputStream(new File("data.txt"))));
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for (int i = 0; i < numOfInts; i++)
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dis.readInt();
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dis.close();
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}
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},
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new Tester("Mapped Read") {
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@Override
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public void test() throws IOException {
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FileChannel fc =
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new FileInputStream(new File("data.txt")).getChannel();
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IntBuffer ib = fc.map(FileChannel.MapMode.READ_ONLY,
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0 , fc.size()).asIntBuffer();
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while (ib.hasRemaining())
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ib.get();
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fc.close();
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}
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},
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new Tester("Stream Read/Write") {
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@Override
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public void test() throws IOException {
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RandomAccessFile raf = new RandomAccessFile(
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new File("data.txt"), "rw");
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raf.writeInt(1);
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for (int i = 0; i < numOfUbuffInts; i++) {
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raf.seek(raf.length() - 4);
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raf.writeInt(raf.readInt());
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}
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raf.close();
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}
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},
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new Tester("Mapped Read/Write") {
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@Override
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public void test() throws IOException {
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FileChannel fc = new RandomAccessFile(
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new File("data.txt"),"rw").getChannel();
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IntBuffer ib = fc.map(FileChannel.MapMode.READ_WRITE,
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0,fc.size()).asIntBuffer();
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ib.put(0);
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for (int i = 1; i < numOfUbuffInts; i++)
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ib.put(ib.get(i-1));
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fc.close();
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}
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}
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};
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public static void main(String[] args) {
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for (Tester tester : tests)
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tester.runTests();
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}
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}

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