使用NIO建立简单的http服务器

 ?1 import java.io.IOException; ?2 import java.net.InetSocketAddress; ?3 import java.nio.ByteBuffer; ?4 import java.nio.CharBuffer; ?5 import java.nio.channels.SelectionKey; ?6 import java.nio.channels.Selector; ?7 import java.nio.channels.ServerSocketChannel; ?8 import java.nio.channels.SocketChannel; ?9 import java.nio.charset.Charset; 10 import java.util.Iterator; 11 ?12 public class NioServer { 13 ????private String ip; 14 ?15 ????private int port; 16 ?17 ????private Selector selector; 18 ?19 ????public NioServer(String ip, int port) { 20 ????????this.ip = ip; 21 ????????this.port = port; 22 ????} 23 ?24 ????public void startListen() throws IOException { 25 ????????selector = Selector.open(); 26 ????????ServerSocketChannel serverChannel = ServerSocketChannel.open(); 27 ????????serverChannel.configureBlocking(false); 28 ????????serverChannel.register(selector, SelectionKey.OP_ACCEPT); 29 ????????serverChannel.bind(new InetSocketAddress(ip, port)); 30 ?31 ????????while (true) { 32 ????????????//不能使用select方法，该方法会阻塞，如果在阻塞过程中channel状态就绪，会因此处阻塞而无法执行。 33 ????????????//所以，如果调用阻塞方法，下面对channel状态的处理得另起一个常驻线程 34 ????????????int result = selector.selectNow(); 35 ????????????if (result == 0) { 36 ????????????????continue; 37 ????????????} 38 ?39 ????????????Iterator<SelectionKey> it = selector.selectedKeys().iterator(); 40 ????????????while (it.hasNext()) { 41 ????????????????SelectionKey key = it.next(); 42 ????????????????if (key.isAcceptable()) { 43 ????????????????????accept(key); 44 ????????????????} else if (key.isReadable()) { 45 ????????????????????read(key); 46 ????????????????} else if (key.isWritable()) { 47 ????????????????????write(key); 48 ????????????????} else { 49 ????????????????????System.out.println("Unknow selector type"); 50 ????????????????} 51 ?????????????????52 ????????????????//一定要调用remove方法将已经处理过的SelectionKey清除掉，否则会造成后面的请求无法接受 53 ????????????????it.remove(); 54 ????????????} 55 ????????} 56 ????} 57 ?????58 ????private void accept(SelectionKey key) throws IOException { 59 ????????System.out.println("Receive connection"); 60 ????????ServerSocketChannel serverSocketChannel = (ServerSocketChannel) key.channel(); 61 ????????SocketChannel channel = serverSocketChannel.accept(); 62 ?????????63 ????????if (channel != null) { 64 ????????????channel.configureBlocking(false); 65 ????????????channel.register(selector, SelectionKey.OP_READ); 66 ????????} 67 ????????System.out.println("Connection end"); 68 ????} 69 ?????70 ????private void read(SelectionKey key) throws IOException { 71 ????????System.out.println("Start read"); 72 ????????SocketChannel channel = (SocketChannel) key.channel(); 73 ????????ByteBuffer buffer = ByteBuffer.allocate(64); 74 ????????boolean hasContent = false; 75 ?????????76 ????????//这里的判断条件不能是不等于-1，因为channel一直都在，只是在数据被读完后里面为空，返回的长度是0.用-1判断会无限循环无法退出 77 ????????while (channel.read(buffer) > 0) { 78 ????????????buffer.flip(); //切换为读模式 79 ????????????CharBuffer cb = Charset.forName("UTF-8").decode(buffer); 80 ????????????System.out.print(cb.toString()); 81 ????????????buffer.clear(); 82 ????????????hasContent = true; 83 ????????} 84 ?????????85 ????????if (hasContent) { 86 ????????????//设置interestOps，用于写响应 87 ????????????key.interestOps(SelectionKey.OP_WRITE); 88 ????????} else { 89 ????????????channel.close(); 90 ????????} 91 ????????System.out.println("Read end"); 92 ????} 93 ?????94 ????private void write(SelectionKey key) throws IOException { 95 ????????System.out.println("Start write"); 96 ????????SocketChannel channel = (SocketChannel) key.channel(); 97 ?????????98 ????????String resText = getResponseText(); 99 ????????ByteBuffer buffer = ByteBuffer.wrap(resText.getBytes());100 ????????101 ????????//此处不可使用channel.write(buffer) != -1来判断，因为在两端都不关闭的情况下，会一直返回0，导致该循环无法退出102 ????????while (buffer.hasRemaining()) {103 ????????????channel.write(buffer);104 ????????}105 ????????channel.close();106 ????????System.out.println("End write");107 ????}108 ????109 ????private String getResponseText() {110 ????????StringBuffer sb = new StringBuffer();111 ????????sb.append("HTTP/1.1 200 OK\n");112 ????????sb.append("Content-Type: text/html; charset=UTF-8\n");113 ????????sb.append("\n");114 ????????sb.append("<html>");115 ????????sb.append(" ?<head>");116 ????????sb.append(" ???<title>");117 ????????sb.append(" ?????NIO Http Server");118 ????????sb.append(" ???</title>");119 ????????sb.append(" ?</head>");120 ????????sb.append(" ?<body>");121 ????????sb.append(" ???<h1>Hello World!</h1>");122 ????????sb.append(" ?</body>");123 ????????sb.append("</html>");124 ????????125 ????????return sb.toString();126 ????}127 ????128 ????public static void main(String[] args) {129 ????????NioServer server = new NioServer("127.0.0.1", 8080);130 ????????try {131 ????????????server.startListen();132 ????????} catch (IOException e) {133 ????????????e.printStackTrace();134 ????????}135 ????}136 137 }

 1 ????????while (true) { 2 ????????????SocketChannel channel = serverChannel.accept(); 3 ????????????if(channel != null) { 4 ????????????????channel.configureBlocking(false); 5 ????????????????channel.register(selector, SelectionKey.OP_READ); 6 ????????????} 7 ?????????????8 ????????????//不能使用select方法，该方法会阻塞，如果在阻塞过程中channel状态就绪，会因此处阻塞而无法执行。 9 ????????????//所以，如果调用阻塞方法，下面对channel状态的处理得另起一个常驻线程10 ????????????int result = selector.selectNow();11 ????????????if (result == 0) {12 ????????????????continue;13 ????????????}14 15 ????????????Iterator<SelectionKey> it = selector.selectedKeys().iterator();16 ????????????while (it.hasNext()) {17 ????????????????SelectionKey key = it.next();18 ????????????????if (key.isReadable()) {19 ????????????????????//读取请求中的数据20 ????????????????????read(key);21 ????????????????} else if (key.isWritable()) {22 ????????????????????//写响应数据23 ????????????????????write(key);24 ????????????????} else {25 ????????????????????System.out.println("Unknow selector type： " + key.readyOps());26 ????????????????}27 ????????????}28 ????????}