自己想了一下怎么實現,就寫了,沒有深究是否合理.更多處理沒有寫下去,例如收件人不在線,應該保存在數據庫,等下一次連接的時候刷新map,再把數據發送過去,圖片發送也沒有做,也沒有用json格式

socket很奇怪,我用客戶端連接上了服務器,沒有發送消息的情況下,斷開電腦網絡,是不會出現問題,然后在把電腦網絡連接上,通訊依然正常,正常斷開也不出問題,但是用idea直接按stop鍵,那么服務端就會出問題了,讀取事件會一直為true,造成死循環,消耗CPU,所以必須要判斷一下客戶端連接是否斷開了

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只需要把客戶端代碼啟動幾個,修改一些userName以及收件人,就可以測試,實現類似QQ微信即時通訊,聊天功能

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服務端代碼

package serversocketchannel;import java.io.IOException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.SelectionKey; import java.nio.channels.Selector; import java.nio.channels.ServerSocketChannel; import java.nio.channels.SocketChannel; import java.nio.charset.Charset; import java.util.Iterator; import java.util.concurrent.ConcurrentHashMap;/*** * @author ZhenWeiLai**/ public class ServerSocketChannelNonBlocking {private static ServerSocketChannel serverSocketChannel = null;private static Charset charset = Charset.forName("GBK");//設置編碼集,用于編碼,解碼private static Selector selector = null;//保存客戶端的mapprivate static final ConcurrentHashMap<String,SocketChannel> clientSockets = new ConcurrentHashMap<>();static{try {serverSocketChannel = ServerSocketChannel.open();serverSocketChannel.socket().setReuseAddress(true);serverSocketChannel.socket().bind(new InetSocketAddress(8000));serverSocketChannel.configureBlocking(false);//設置為非阻塞selector = Selector.open();//實例化一個選擇器} catch (IOException e) {e.printStackTrace();}}public static void main(String[] args) {service();}private static void service(){SocketChannel clientChannel = null;SelectionKey selectionKey = null;SocketChannel targetChannel = null;try {serverSocketChannel.register(selector,SelectionKey.OP_ACCEPT);//服務端監聽連接while(true){selector.select();//阻塞至有新的連接就開始處理Iterator<SelectionKey> selectionKeys = selector.selectedKeys().iterator();while(selectionKeys.hasNext()){selectionKey = selectionKeys.next();if(selectionKey.isAcceptable()){//如果事件是連接事件ServerSocketChannel serverChannel = (ServerSocketChannel)selectionKey.channel();//獲取事件綁定的channelclientChannel = serverChannel.accept();//連接獲取帶客戶端信息的socketChannelclientChannel.configureBlocking(false);//客戶設置為非阻塞,因為非阻塞才支持選擇器.避免盲等浪費資源ByteBuffer byteBuffer = ByteBuffer.allocate(1024);//作為每一個客戶端的附件緩沖器/*** 只監聽讀事件,這里千萬別監聽寫事件,因為只要連接有效,那么寫事件會一直為true,導致死循環,很耗資源* 可以跟serverSocket用同一個選擇器,因為綁定的channel不同*/clientChannel.register(selector,SelectionKey.OP_READ,byteBuffer);}else if(selectionKey.isReadable()){//只要有客戶端寫入,那么就可以處理//獲取客戶端附件,也就是寫入的數據ByteBuffer byteBuffer = (ByteBuffer)selectionKey.attachment();//從selectionKey獲取客戶端的channelSocketChannel socketChannel = (SocketChannel)selectionKey.channel();//把附件讀出,解碼為字符串String msg = read(socketChannel,byteBuffer);//這里用了->分割收件人,->后面跟著的字符串是收件人if(msg.indexOf("->")!=-1){//內容String content = msg.substring(0,msg.lastIndexOf("->"));//從map里獲取收件人的sockettargetChannel = clientSockets.get(msg.substring(msg.lastIndexOf("->")+2));//實例化一個緩沖區,用來寫出到收件人的socketChannelByteBuffer temp = ByteBuffer.allocate(1024);temp.put(charset.encode(content));//寫出 handleWrite(targetChannel,temp);}else{//如果內容沒有收件人,那么視為第一次連接,客戶端發過來的userName,作為KEY存入MAP clientSockets.put(msg,socketChannel);}}selectionKeys.remove();}}} catch (IOException e) {try {if(selectionKey!=null)selectionKey.cancel();if(clientChannel!=null){clientChannel.shutdownInput();clientChannel.shutdownOutput();clientChannel.close();}if(targetChannel!=null){targetChannel.shutdownInput();targetChannel.shutdownOutput();targetChannel.close();}} catch (IOException e1) {// TODO Auto-generated catch block e1.printStackTrace();}e.printStackTrace();}}private static String read(SocketChannel socketChannel,ByteBuffer byteBuffer){//重置position limit為寫入做準備 byteBuffer.clear();try {int flag =socketChannel.read(byteBuffer);//判斷客戶端是否斷開連接if(flag==-1){//如果客戶端無故斷開,一定要關閉,否則讀取事件一直為true造成死循環,非常耗資源 socketChannel.close();}} catch (IOException e) {try {socketChannel.close();} catch (IOException e1) {e1.printStackTrace();}e.printStackTrace();}//position =0 limit等于有效下標,為寫出做準備 byteBuffer.flip();return charset.decode(byteBuffer).toString();}//寫出private static void handleWrite(SocketChannel socketChannel,ByteBuffer byteBuffer){synchronized (byteBuffer) {byteBuffer.flip();try {socketChannel.write(byteBuffer);} catch (IOException e) {try {socketChannel.close();} catch (IOException e1) {e1.printStackTrace();}e.printStackTrace();}}} }

客戶端代碼

package socketchannel;import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.net.InetSocketAddress; import java.net.SocketAddress; import java.nio.ByteBuffer; import java.nio.channels.ClosedChannelException; import java.nio.channels.SelectionKey; import java.nio.channels.Selector; import java.nio.channels.SocketChannel; import java.nio.charset.Charset; import java.util.Iterator;/*** Created by lzw on 17-2-28.*/ public class SocketChannelNonBlockingClient {private static Charset charset = Charset.forName("GBK");private static ByteBuffer receiveBuffer = ByteBuffer.allocate(10240);private static ByteBuffer sendBuffer = ByteBuffer.allocate(10240);private static SocketChannel socketChannel = null;private static Selector selector = null;private static String userName = "client1";//客戶端名private static String targetName = "client2";//收件人名public static void main(String[] args) {try {socketChannel = SocketChannel.open();//連接到服務端SocketAddress socketAddress = new InetSocketAddress("19.95.103.112",8000);selector = Selector.open();//實例化一個選擇器socketChannel.configureBlocking(false);//設置為非阻塞//先監聽一個連接事件 socketChannel.register(selector,SelectionKey.OP_CONNECT);//連接 socketChannel.connect(socketAddress);//jdk 1.8的lambda表達式，用一個線程監控控制臺輸入new Thread(()->{try {receiveFromUser();} catch (IOException e) {e.printStackTrace();}}).start();talk();} catch (IOException e) {// TODO Auto-generated catch block e.printStackTrace();}}private static void talk(){try {while(true){selector.select();//阻塞直到連接事件Iterator<SelectionKey> readyKeys = selector.selectedKeys().iterator();while(readyKeys.hasNext()){SelectionKey key =readyKeys.next();if(key.isConnectable()){//非阻塞的情況下可能沒有連接完成，這里調用finishConnect阻塞至連接完成 socketChannel.finishConnect();//連接完成以后，先發送自己的userName以便保存在服務端的客戶端map里面synchronized (sendBuffer){SocketChannel socketChannel1 = (SocketChannel)key.channel();sendBuffer.clear();sendBuffer.put(charset.encode(userName));send(socketChannel1);socketChannel.register(selector,SelectionKey.OP_READ);//僅監聽一個讀取事件 }}else if(key.isReadable()){//處理讀事件 receive(key);}readyKeys.remove();}}} catch (ClosedChannelException e) {try {socketChannel.close();} catch (IOException e1) {e1.printStackTrace();}e.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch block e.printStackTrace();}}/*** 從控制臺獲取用戶輸入* @throws IOException*/private static void receiveFromUser() throws IOException{//阻塞直到控制臺有輸入BufferedReader br = new BufferedReader(new InputStreamReader(System.in));for(String msg = br.readLine();msg!=null&&!msg.equals("bye");msg = br.readLine()){//同步鎖避免線程競爭synchronized (sendBuffer) {sendBuffer.clear();//編碼 sendBuffer.put(charset.encode(msg));//分割副sendBuffer.put(charset.encode("->"));//目標名 sendBuffer.put(charset.encode(targetName));send(socketChannel);}}}/*** 接收服務端的數據* @param key*/private static void receive(SelectionKey key) throws IOException {//獲取服務端的channelSocketChannel channel = (SocketChannel) key.channel();//為寫入緩沖器做準備position=0,limit=capacity receiveBuffer.clear();//從服務端的channel把數據讀入緩沖器 channel.read(receiveBuffer);//position=0,limit=有效下標最后一位 receiveBuffer.flip();//解碼String msg = charset.decode(receiveBuffer).toString();//輸出到控制臺 System.out.println(msg);}/*** 發送到服務端*/private static void send(SocketChannel sendChannel) throws IOException {if(sendBuffer.remaining()!=0){synchronized (sendBuffer){sendBuffer.flip();sendChannel.write(sendBuffer);}}} }

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轉載于:https://www.cnblogs.com/sweetchildomine/p/6517228.html

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