import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.RandomAccessFile;

import java.net.InetSocketAddress;

import java.net.ServerSocket;

import java.nio.ByteBuffer;

import java.nio.MappedByteBuffer;

import java.nio.channels.FileChannel;

import java.nio.channels.ServerSocketChannel;

import java.nio.channels.SocketChannel;

import java.nio.file.Paths;

import java.nio.file.StandardOpenOption;

/*

* Created by 颜群

*/

public class NIODemo {

public static void test1(){

ByteBuffer buffer = ByteBuffer.allocate(100);// new byte[100]

System.out.println("position:" + buffer.position());

System.out.println("limit:" + buffer.limit());

System.out.println("capacity（一旦定义不可改变）:" + buffer.capacity());

//put()

System.out.println("put()...\n");

buffer.put("hello".getBytes() ) ;

System.out.println("position:" + buffer.position());

System.out.println("limit:" + buffer.limit());

//切换模式 写->读：flip()

System.out.println("flip()...\n");

buffer.flip() ;

System.out.println("position:" + buffer.position());

System.out.println("limit:" + buffer.limit());

//get()

System.out.println("get()...\n");

byte[] bs = new byte[ buffer.limit()];

buffer.get( bs ) ;

System.out.println("读取到的数据：" +new String( bs));

System.out.println("position:" + buffer.position());

System.out.println("limit:" + buffer.limit());

}

public static void test2(){

ByteBuffer buffer = ByteBuffer.allocate(8);

for(int i=0;i<buffer.capacity();i++){

buffer.put( (byte) i ) ;// 0 1 2 ... 7

}

buffer.position(2) ;

buffer.limit(5);

ByteBuffer sliceBuffer = buffer.slice();//获取原buffer的局部引用（局部范围：position - limit）

for(int i=0;i<sliceBuffer.capacity();i++)

{

byte b = sliceBuffer.get(i);

b += 100 ;

sliceBuffer.put(i,b) ;

}

buffer.position(0) ;

buffer.limit( buffer.capacity()) ;

while(buffer.hasRemaining()){ //迭代器

System.out.println( buffer.get() );

}

}

public static void test3(){

ByteBuffer buffer = ByteBuffer.allocate(100);

buffer.put("helloworld".getBytes()) ;//position:0 ->10

buffer.mark();//mark: 10

System.out.println("position:"+buffer.position());

System.out.println("mark:"+buffer.mark().position());

buffer.put("123".getBytes()) ; ////position:10 ->13

System.out.println("position:"+buffer.position());

buffer.reset() ;//将position恢复到mark的位置

System.out.println("position:"+buffer.position());

byte[] bs = new byte[5] ;

buffer.get(bs , 2 ,3) ;//三个参数：存放容器，从第几位开始，取几位

System.out.println(bs[0]);

System.out.println(bs[1]);

System.out.println(bs[2]);

System.out.println(bs[3]);

System.out.println(bs[4]);

System.out.println( new String(bs));

}

public static void test4(){

ByteBuffer buffer = ByteBuffer.allocate(100);

buffer.put("helloworld".getBytes()) ;

//写->读

buffer.flip() ;

byte[] bs = new byte[ buffer.limit()] ;

buffer.get( bs) ;

System.out.println(new String(bs) );

//读->读

buffer.rewind() ;

buffer.get( bs) ;

System.out.println(new String(bs));

//clear():并没有真正的删除元素，只是将元素处于一个被 遗忘的状态

buffer.clear();

System.out.println( (char)buffer.get(2) );//unicode (ascii)

}

public static void test5(){

/* FileChannel.open() ->Channel

FileInputStream/FileOutputStream/RandomAccessFile:getChannel() ;

Socket/ServerSocket/DatagramSocket:getChannel()

*/

}

// 尝试使用 buffer和channel进行 文件复制

// 使用非直接缓冲区

public static void test6(){

long start = System.currentTimeMillis();

FileInputStream input = null ;

FileOutputStream out = null ;

FileChannel inChannel = null ;

FileChannel outChannel = null ;

try{

ByteBuffer buffer = ByteBuffer.allocate(1024);//非直接缓冲区

input = new FileInputStream("d:/mvnrep.rar");

out = new FileOutputStream("d:/mvnrep2.rar");

inChannel = input.getChannel();

outChannel = out.getChannel();

while(inChannel.read(buffer ) !=-1){//读

buffer.flip() ;

outChannel.write(buffer) ;//写

buffer.clear() ;

}

long end = System.currentTimeMillis();

System.out.println("复制操作消费时间:" + (end-start));

}catch (Exception e){

e.printStackTrace();

}finally {

try{

if(outChannel != null) outChannel.close();

if(inChannel != null) inChannel.close();

if(out != null) out.close();

if(input != null) input.close();

}catch (Exception e){

e.printStackTrace();

}

}

}

// 尝试使用 buffer和channel进行 文件复制

// 使用直接缓冲区

public static void test7(){

long start = System.currentTimeMillis();

FileInputStream input = null ;

FileOutputStream out = null ;

FileChannel inChannel = null ;

FileChannel outChannel = null ;

try{

ByteBuffer buffer = ByteBuffer.allocateDirect(1024);//直接缓冲区

input = new FileInputStream("d:/mvnrep.rar");

out = new FileOutputStream("d:/mvnrep3.rar");

inChannel = input.getChannel();

outChannel = out.getChannel();

while(inChannel.read(buffer ) !=-1){//读

buffer.flip() ;

outChannel.write(buffer) ;//写

buffer.clear() ;

}

long end = System.currentTimeMillis();

System.out.println("复制操作消费时间:" + (end-start));

}catch (Exception e){

e.printStackTrace();

}finally {

try{

if(outChannel != null) outChannel.close();

if(inChannel != null) inChannel.close();

if(out != null) out.close();

if(input != null) input.close();

}catch (Exception e){

e.printStackTrace();

}

}

}

// 尝试使用 buffer和channel进行 文件复制

// 使用直接缓冲区(零拷贝)

public static void test8(){

long start = System.currentTimeMillis();

//channel buffer

try {

FileChannel inChannel = FileChannel.open(Paths.get("D:/mvnrep.rar") );

FileChannel outChannel = FileChannel.open(Paths.get("D:/mvnrep2.rar") , StandardOpenOption.WRITE, StandardOpenOption.READ,StandardOpenOption.CREATE);

//物理映射文件

MappedByteBuffer inMappedBuf = inChannel.map(FileChannel.MapMode.READ_ONLY, 0, inChannel.size());

MappedByteBuffer outMappedBuf = outChannel.map(FileChannel.MapMode.READ_WRITE, 0, inChannel.size());

byte[] st = new byte[ inMappedBuf.limit() ] ;

inMappedBuf.get( st);

outMappedBuf.put( st);

inChannel.close();

outChannel.close();

long end = System.currentTimeMillis();

System.out.println("直接缓冲区（物理映射文件）,花费时间："+ (end-start));

}catch(Exception e){

e.printStackTrace();

}

}

public static void test9(){

try{

RandomAccessFile raf = new RandomAccessFile( "d:/a.txt","rw") ;

FileChannel fileChannel = raf.getChannel();

//只修改内存中的mappedByteBuffer

MappedByteBuffer mappedByteBuffer = fileChannel.map( FileChannel.MapMode.READ_WRITE, 0,raf.length());

mappedByteBuffer.put(1,(byte)'X') ;

mappedByteBuffer.put(4,(byte)'Y') ;

//硬盘中的文件会自动修改（操作系统的功能）

raf.close();

}catch (Exception e){

e.printStackTrace();

}

}

public static void test10(){

long start = System.currentTimeMillis();

try{

FileChannel inChannel = FileChannel.open(Paths.get("d:/mvnrep.rar"));

FileChannel outChannel = FileChannel.open( Paths.get("d:/mvnrep2.rar"),StandardOpenOption.WRITE,StandardOpenOption.READ,StandardOpenOption.CREATE );

//零拷贝

inChannel.transferTo( 0,inChannel.size(),outChannel ) ;

// outChannel.transferFrom( 0,inChannel.size(),inChannel ) ;

inChannel.close();

outChannel.close();

long end = System.currentTimeMillis();

System.out.println("零拷贝时间："+ (end-start));

}catch (Exception e){

e.printStackTrace();

}

}

public static void server() throws Exception {

ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();//类似于IO技术中的 ServerSocket

serverSocketChannel.bind( new InetSocketAddress(8888)) ;

SocketChannel sChannel = serverSocketChannel.accept();

System.out.println("客户端连接成功...");

ByteBuffer buffer = ByteBuffer.allocate(1024);

long start = System.currentTimeMillis();

FileChannel outChannel = FileChannel.open(Paths.get("d:/123.rar"), StandardOpenOption.WRITE, StandardOpenOption.CREATE);

while(sChannel.read(buffer ) != -1){ //3.接收

buffer.flip();

outChannel.write(buffer); //4.输出

buffer.clear();

}

sChannel.close();

outChannel.close();

serverSocketChannel.close();

long end = System.currentTimeMillis();

System.out.println("接收："+(end-start));

}

public static void client() throws Exception {

long start = System.currentTimeMillis();

SocketChannel socketChannel = SocketChannel.open( new InetSocketAddress( "127.0.0.1" ,8888) );

FileChannel inFileChannel = FileChannel.open(Paths.get("D:/mvnrep.rar"), StandardOpenOption.READ);

//buffer+channel

ByteBuffer buffer = ByteBuffer.allocate(1024);

while( inFileChannel.read( buffer ) != -1){//1.读取

buffer.rewind() ;

socketChannel.write( buffer) ;//2.发送

buffer.clear() ;

}

if(inFileChannel!= null) inFileChannel.close();

if(socketChannel!= null) socketChannel.close();

long end = System.currentTimeMillis();

System.out.println("客户端：" + (end-start));

}

public static void client2() throws Exception{

long start = System.currentTimeMillis();

SocketChannel socketChannel = SocketChannel.open( new InetSocketAddress( "127.0.0.1" ,8888) );

FileChannel inFileChannel = FileChannel.open(Paths.get("D:/mvnrep.rar"), StandardOpenOption.READ);

//使用直接缓冲区（零拷贝）

inFileChannel.transferTo(0, inFileChannel.size() ,socketChannel ) ; // a transferFrom/transferTo b

long end = System.currentTimeMillis();

System.out.println("直接缓冲区方式（客户端）发送文件："+(end-start));

inFileChannel.close();

socketChannel.close();

}

public static void main(String[] args) throws Exception {

// test1();

// test2();

// test3();

// test4() ;

// test6() ; //使用非直接缓冲区 复制

// test7() ;//使用直接缓冲区 复制

// test8() ;//使用直接缓冲区 复制（物理映射文件）

// test9() ;

// test10() ;

// server();//非直接 (由于服务端，无法直接感知 客户端发送的文件大小，因此无法精准的开辟一块合适的 直接缓冲区大小)

// client();//非直接

// client2();//直接

}

}