java的nio之:java的nio系列教程之channel的概念

时间:2021-12-09 19:35:50

一:java的nio的channel

Java NIO的通道类似流,但又有些不同:

==>既可以从通道中读取数据,又可以写数据到通道。但流的读写通常是单向的。

==>通道可以异步地读写。

==>通道中的数据总是要先读到一个Buffer,或者总是要从一个Buffer中写入。

正如上面所说,从通道读取数据到缓冲区,从缓冲区写入数据到通道。如下图所示:

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P6ZgBeoZFiB/LAaJBvC2lkvUvS3lOpAiDoGukbUa0SWpoBeAUOEDuQB8boKj0b8FTtA1We8iCjtsGo03j5KlywRTfFBKO+rhxU7fsuaWS9S9Lew8fPb9T05rMHdDXXAwaNcsEW3ZRBc0swtvqoRphmQ9wMVXtbSCPvXTRv7Bs7rfnsAf3t0oCBI12zRXfUcrsEgDx+ttiB2IOuybcFR4N8APL4OfU+rxma6lvqynz7Rbhmo+5FaNXpam4AkCc8J3Ys9qBBvi2kkfWuSntPeVBg8luar99pLrvoG9z1AygJgKaS80wwyuNn+wyOFzsWe9CUni34qvYAAqesbDqx06CpbqooChjwsMu26xb0Dbd0tWUAlMnS+lAd29Eg3xbcpb2Hj1/QM5vrPn2pueySj1+gLKjnry3kjEHXePfXfwFQJr/tpqUeNMi3jTSy3qXX5MP/0ecN5YUa9RbN9bPKYQk+ilDrffo6U84Lxla/UUlS+/y8B0JX6dmCu2pvopzzrr78gu6SuuHq6YDBo+ShD7k4AEnRa27fLb3AjAafwfEhL+8VO5xeoWpvC2lkvcvTHkD/Vw7VZ6U25u5uKrvUqqkJUA33knN3DY9g0Gurr2lrywH4jUoKeXmvpzxI7KB6iW68tYUkXiJx7vcKnp/hPSi+4W9v6DU1ek2NX8hAmVIlCwwRJRgXM2obdXXluvoq06XKyqR05Zx3xQ7KAaja20Iib4yi3eapeHypPH62JvudplOf6eoqdXWVHp7efsFhHl6+ADxlvoK+xeqTuAVPma9g0ENgTDC0NNwSDHpTu9+opKDZ77nvHF4XumYDY1qxo5C6Fq0kbksR8+5uL6Wq36KPApPfas79RFuQ3VpdpK2rFDEe1/AOjfKLTfKf+KJsiOS+3NI+AXIlgBatoUXrrncNu5jpFRORK74Vx0aGuhJDVbH+huS+4NlRfAbHe4dE9Znybin7271NWo3YUbiHALly9vTF4sYgobQnhLiGK7/xlhAiCZT2hHCH0p4Q7lDaE8IdSntCuENpTwh3KO0J4Q6lPSHcobQnhDuU9oRwh9KeEO5Q2hPCHUp7QrhDaU8IdyjtCeEOpT0h3KG0J4Q7lPaEcIfSnhDuUNoTwh1Ke0K4Q2lPCHco7QnhDqU9IdyhtCeEO5T2hHCH0p4Q7lDaE8IdSntCuENpTwh3KO0J4Q6lPSHcobQnhDuU9oRwh9KeEO5Q2hPCHUp7QrhDaU8IdyjtCeEOpT0h3KG0J4Q7lPaEcIfSnhDuUNoTwh1vsQPoylBXYqwtMdSVGGtLxY7FMbxCI71DojyVKh/VCLFjcZa8/O+u37wsdhTuYehDsRMTnhI3BkmkfWtZgTb/oLYgu7W6SOxYnMs7NMovNskvbrbfqCSxY3GYvPzvNuxYKXYU7uTNlTvEzXyR015bkK05uq61rKC9RTYoDt6+Xor+3qFDxIvLkYyaCsOdCgCt5YWG2pLG3N2Nubu9lKrA5LcVjy8VOzoHMNX5qKihQ6KGih2L1N0ouV5Scv36zcucpn1rdVF91mstV08C8FKE+sVM8R0+yS9miljxuIa+vFB3Sa0rPmGor6jPSm08vrXfoo98H54sdlwOMCQqavITiWJHIX1CScl1sWMQKe1brp6s/Xi+oG3w9FUETFigmLTYw9sXAJggSjwuI4sYLYsYrZy2qrng8N0TOw21JTUZTwfPz+gDZZ8xJjCj2FFIHWNM7BAAUdK+MXd3fVYqAFlkQshzmzx9FQDA2R7jH5csj31Sc/yDpnNf1WelGsoLgudniB1UrzAIjLN/oh0YJFHYXJ32uktqU84rHpunfPI1ABAk8UK4noenT9D0dO+waM33GY25uz1DIpVJ6WIHZT/GmMDrv9J2PFb71uqiuk8XA1CMnxc49fesrw/pbeE/bo6Hb0B99h81X78jGzTWfWf4aZBvCx7Tvu7TlwRtg++wCYFTV/A2qr8P+cgpxluL7uZ9ceeLZQP+eNnDx0/siOzBIFDaW8XdIF9bkN1aVuAVEBI847+5Hdj3RPH4f2ivnzLcuqbJfifomc1ih2MPGuTbgq9qz1p1mqPrAPiPn+8p86NS313gvy2+8/X/NObuVkxb7aVUiR3Og2OMpvSs4yrt9TdOt5YVeAX0C4hLhkA7xz34DZvoN/w3ums/NZ89EDjV/S56o0G+Lfga5OsKDwPwj03y8PSmEX5PfIdN1F37SVd42C3Tnqb0bMDXIF9bkA1AFjmOhvf34Td0osZb1nL1pKBt8JQHiR3Og6Hz9rbgqNob6koMtSWevgGyiNF9/jq83vCUyWWDxrSU5LeWXXC7K3ap2tuCo2rPmhsAeAUPoqN6q7wVYS2Aoa7EV+xIHhQd29uCo2ovaOsBePkHU6m3yjS2N2qqxQ7kgVG1twVH1V5fVgDASx5EaW+Vh38QALS2iB3IA6NqbwuOqj3TNgDwkAcxGuRbIzTdETsEezFG/1/r+Kn2ZoxRtbdOGruFHRijam+dRO5DceU1+QKdvbOBJHYLOzDQVXrWMUjibd211Z4u1LHKjas9E6RRyqSMoyk9Mxrk20Iau4UdaErPFhxN6bVhNMi3gdumPZ3AswGX1b73g/zKnJlzP/m2ffXFN1tTY9tWLq+ZsAG79m56tLcbsYuDti6N3cIOTrrx9tKHGe/t69o4KyN10SNWOt4+/PffbyoFMHbNkqX4rn157axAhwdpOw7TvrdTeiVfb41eh48O/fnIAFND7Z5V6T4Tko/nzUsE2ibDjCLVSwdt3dpx0N3mlkB/aV7C55Rr8hmACVMztozq39507qeFqRn44NWF98v8in9sKo1/Y/HaWYFAxZeT25ch9rwjb4P8Xp7XzT8YvY5lfvWHJeHGttQIXrItvWjSlmkZo/UrRwJGABCMIk0gOGjrPVcDfavx/x35V51Gu2bxlN5twymcNMgXAIAZmbHjdR038a0F59Z/cfGpcSPDeuxnZMBDEf4CM3ZeFhmH1b43g/zaPXuPYeHqlHCh89tlzIodq1cMDC0VhEhTnb15cuare9UAgLQdf9rYVhBydi5L+tK8bNFetPa3W7FjNVZu3dbpVz21AwDOHZStNB9nJK3dcGR2qOnPAwAm9PbdvIfdQp1XvH3fj7UNzZ/9nxd6twFnYUwQnHC5DhNMr6pR6NI4VBEqGAVU7p96GNv/84Vxpt9U7p96GOmTy7acLACwKvNIe59VmUcQ/+YPE2MBnM9b/AfzN7LEpy9In6lo63thYHq/T7YUoP2RDv9zpDGr7S7n7auL85C2KLr7M0SOiwZMn7dtBLBt45nMg7uODEBpdkb0yu0xB1NTBiDnw1eSsEqfOwLo1G7usvKbzIO79J269NSO0uyM6E3IPLgrZQBQ9c+Zz705k607Mjukvdr3+hCj627xy7Wq7ft+/OVaFYCYyLCYyJ4rnKicdN6eMZgOHzpe1wunN2SNWft9OGPG9mOrtndLAQAGRa/+XpH15DfYnjJ/LICqjmVmvP3NP9K2IGVfSqIKqC5+f8G+zZj3+gwFIAA3P8mJ2vZ9SigAyy068M+RxpStm5zAq6opBOIg3PdFYwCS1ixMUQlgiByfkIQviisEqIqPfhmbeeBh09Yt2u/Tpcen+nDT5aQ175naoZp0JKNKlvpDzqzfJZoju3+ENrCo9rUNzdv3/ajOK25viYnsf68+kuCkq/QYgDO5aU/mdm4eVF1lHKECIDAAzCi0pX3bqmW75XK1ekv5mNXPPhFuFBgQPnz1tjtL0i5eSh4/EgIDxkxW9WNG51Vk/qo9Y/bfeGtKBsF43yG0ACBuYJB5K+EhceYuwzfmvAIYIQDnDslWfQcgzvxUPXXpob2yptCyHcCA8CR8efTsnMRHBBsitPUvNQrs47/n7f3mrL610ys2IDTw47/n9W4Djne1qBwAg3OO7Rnw2KTNG4aHdrRVH5im/vP24tgNw0Nh7Jz27auW7RbLVQ03gcER8o5Qw5Vj8POF84/EjDWyLr9yAv6qPXpR7U2Jx6xXe4vHdKyWHsmMfv8KAGCqOmvB5vn72h7WU5ce2ssr1YB6Veq2zhuOu0cXuzEA+789/+nde3y6TlXt3cO5kvs+6UCPcoVTqz2MQqcK3P/ZLSOPpd+4WDXkcZUgoFO1b1u1bLdYrrrzC/DL6s+Pdd5KRNcuzsJltbf/bw6OeQzLTxVvNB3JWyg98qfoLcjcvyxFZXry9sRrW6069cr7V9K2b9tomvWpPrW542E9dGE9tA8MS8LIZ/cvS+n6wbbdu9iLMQBPTxpRWDr47JWyLr8MDQpYOndC7zbgeFeLKoqLzjAGwQkZIzBAgNDlul+VcjQaOq4UYKxtsrh91bLdYlmlHI2Bj36W+NvwLtvp/lROIY2JfBeft7d/pjcoZUHi8rTje+YO7Zxyd47nXMG85Slh5pE5WPswu221olqNxDfi29orqtVAHOsY5N+jS09PFRYShyt/PXM7ZUa/bhF26WIvJgAIDfL/cM3vcvJ/3b7vx8rbmvZf3m1ukeDZu/2HzhQXmc/gOf7ZzaOozvlSobmIoH/vz0yjq4qyJjbGHwCqm8qBCMHcDsFcXDuW+wdEoPLsv5p+87T/vTclOLkeSyPvPV24LQYm2P8TP0P9fPHyha+vPd/eeHXtU+uXn0lULxtqbgE6dTGthoclIefo+bYuaTkACstq79elx/ahK9Ji1FsP7qk0t+dkvi576mPzapcu9v1YjBYSE4b9Zf2LK56b1H59juVbgNSYqr3jf9B2l0/HT/XBNVdiU6OjBSYIAaoEXPyx6rbABKEpN+P0RcD0YNa20Hk5LDFVdfGD07lV5l9d2Z21PPmEadWyi5N+pJH1rh7k9+rYL3HZev3EY7LVazoOrZ9fql82rO1p2+qt5cicGaFK2JV2Idrc6+HMz9erD72VtO2vexKWmI8LundhPbUjMvllfcQx2YtrlpsjmKxWP52I7l3s1Xm/kPl4vTRz/KzHR+0+dPpvPxSevVJW29AcGnSPSiU6BuaMnZoxIP/Mf808Y9kYmzpz5XQ5YwyQT3p3StWsE6YHTNswZVr+CYuLYiwjMi/3mz5558ALry75y+fm9pjXDo+NuXcXx5PIlJ6HC95/NN+s0xxdp4iZHDDiCWdvy901Ff3YWHxSmfy2csbbXX5VXFrzf/fljhk+YMVzk0SJrSf7D+3Yf2jnsNiwYSO7HjGTLn69cuvXyzUvzH31hblifhWC66o9A5PINKaU3acaxESGfbjmd6brdiTISVN6fQyHg3z6dB0bWHtnHDN8gGsCeWBOmtLrY6SR9+5yTT43pLFb2IG+8dYWEpnTo4/ZkBpJ7BZ2oEG+LaSR9W5z3p4bbjv9wRijtLeKv2pPg3xbSGO3sANVe1tI5N/rTuftuSCR/eLBMeaU8/Z9jEReIje5FYcjktgt7EDV3hbSyHrXpL2PLwBm0NGxvVUenq58I3Yo5uS7WPoGaeS9K3YyH9UIAEJLM1V7qxgziB2CnWhKzxYcDfK9lCoARj2lvXVM3wzAKzRS7EAeGA3ybSGNrHdJ2nsqVQAEXSN9I6pVQkszAK9AqV6K1zNGV+nZgKdqH6jylAcZtQ1GncbLV+GCLbopJhj1deWgat93SSPrXZL2Hj5+fqOmN589oKu5HjBolAu26KYMmluCsdVHNcI0G+JmqNrbQhp576J5Y9/Yac1nD+hvlwYMHOmaLbqjltslAOTxs8UOxB50Tb4tOBrkA5DHz6n3ec3QVN9SV+bbL8I1G3UvQqtOV3MDgDzhObFjsQcN8m0hjax3Vdp7yoMCk9/SfP1Oc9lF3+CuH0BJADSVnGeCUR4/22dwvNix2IOm9GzBV7UHEDhlZdOJnQZNdVNFUcCAh122Xbegb7ilqy0DoEzu+qE67oIG+bbgLu09fPyCntlc9+lLzWWXfPwCZUES/VIn1zPoGu/++i8AyuS33bTUgwb5tpFG1rv0mnz4P/q8obxQo96iuX5WOSzBRxFqvU9fZ8p5wdjqNyqp++fnuRG6Ss8W3FV7E+Wcd/XlF3SX1A1XTwcMHiUPfcjFAUiKXnP7bukFZjT4DI4PeXmv2OH0ClV7W0gj612e9gD6v3KoPiu1MXd3U9mlVk1NgGq4l5y7a3gEg15bfU1bWw7Ab1RSyMt7PeX3+PYrt0I33tpCEi+ROPd7Bc/P8B4U3/C3N/SaGr2mxi9koEypkgWGiBKMixm1jbq6cl19lelSZWVSunLOu2IH5QBU7W0hkTdG0W7zVDy+VB4/W5P9TtOpz3R1lbq6Sg9Pb7/gMA8vXwCeMl9B3yJWbI7lKfMVDHoIjAmGloZbgkFvavcblRQ0+z33ncPrQtdsc3x55AAAARVJREFUYEwrdhRS16KVxG0pYt7d7aVU9Vv0UWDyW825n2gLsluri7R1lSLG4xreoVF+sUn+E1+UDZHcl1jaJ0CuBNCiNbRo3fWuYRczvWIicsW34tjIUFdiqCrW3zgtdiDO4jM43jskqs+Ud0vZ3+5t0kr3+/kkJUCunD19sbgxSCjtCSGu4cpvvCWESAKlPSHcobQnhDuU9oRwh9KeEO5Q2hPCHUp7QrhDaU8IdyjtCeEOpT0h3KG0J4Q7lPaEcIfSnhDuUNoTwh1Ke0K4Q2lPCHco7QnhDqU9IdyhtCeEO5T2hHCH0p4Q7lDaE8IdSntCuENpTwh3KO0J4Q6lPSHcobQnhDuU9oRwh9KeEO5Q2hPCnf8PW+4+C7QwAuUAAAAASUVORK5CYII=" alt="" />

二:java的nio的channel的实现

这些是Java NIO中最重要的通道的实现:

==>FileChannel  :

==>DatagramChannel

==>SocketChannel

==>ServerSocketChannel

三:java的nio的channel的实现的作用

==>FileChannel 从文件中读写数据。

==>DatagramChannel 能通过UDP读写网络中的数据。

==>SocketChannel 能通过TCP读写网络中的数据。

==>ServerSocketChannel可以监听新进来的TCP连接,像Web服务器那样。对每一个新进来的连接都会创建一个SocketChannel。

四:java的nio的channel的基本例子

 package com.yeepay.sxf.testnio;

 import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
/**
* 简单测试java的nio中channel组件的作用
* @author sxf
*
*/
public class TestChannelForNio { public static void main(String[] args) throws IOException {
//把文件加载到内存 /usr/sxf/testnio文件
RandomAccessFile aFile = new RandomAccessFile("/usr/sxf/testnio", "rw");
//从文件中获取通道
FileChannel inChannel = aFile.getChannel();
//从通道中注册一个缓冲区,每次48个字节
ByteBuffer buf = ByteBuffer.allocate(48);
//读取第一次
int bytesRead = inChannel.read(buf);
//看文件中是否有数据
while (bytesRead != -1) {
//打印第一次读取字符的个数
System.out.println("Read " + bytesRead); //注意 buf.flip() 的调用,首先读取数据到Buffer,然后反转Buffer,接着再从Buffer中读取数据。
buf.flip(); //打印每一个字符到控制台
while(buf.hasRemaining()){
System.out.print((char) buf.get());
} //清空这次buffer
buf.clear(); bytesRead = inChannel.read(buf); } aFile.close();
}
}