[英]Java NIO client
import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;
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.util.*;
public class EchoServer {
private InetAddress addr;
private int port;
private Selector selector;
private Map<SocketChannel,List<byte[]>> dataMap;
public EchoServer(InetAddress addr, int port) throws IOException {
this.addr = addr;
this.port = port;
dataMap = new HashMap<SocketChannel,List<byte[]>>();
startServer();
}
private void startServer() throws IOException {
// create selector and channel
this.selector = Selector.open();
ServerSocketChannel serverChannel = ServerSocketChannel.open();
serverChannel.configureBlocking(false);
// bind to port
InetSocketAddress listenAddr = new InetSocketAddress(this.addr, this.port);
serverChannel.socket().bind(listenAddr);
serverChannel.register(this.selector, SelectionKey.OP_ACCEPT);
log("Echo server ready. Ctrl-C to stop.");
// processing
while (true) {
// wait for events
this.selector.select();
// wakeup to work on selected keys
Iterator keys = this.selector.selectedKeys().iterator();
while (keys.hasNext()) {
SelectionKey key = (SelectionKey) keys.next();
// this is necessary to prevent the same key from coming up
// again the next time around.
keys.remove();
if (! key.isValid()) {
continue;
}
if (key.isAcceptable()) {
this.accept(key);
}
else if (key.isReadable()) {
this.read(key);
}
else if (key.isWritable()) {
this.write(key);
}
else if (key.isConnectable()) {
this.doConnect(key);
}
}
}
}
private void doConnect(SelectionKey key) {
SocketChannel channel = (SocketChannel) key.channel();
if (channel.finishConnect()) {
/* success */
System.out.println("Connected");
} else {
/* failure */
System.out.println("failure");
}
}
public void connect(String hostname, int port) throws IOException {
SocketChannel clientChannel = SocketChannel.open();
clientChannel.configureBlocking(false);
clientChannel.connect(new InetSocketAddress(hostname,port));
clientChannel.register(selector,SelectionKey.OP_CONNECT);
clientChannel.write(ByteBuffer.wrap(("$Hello "+UserInfo[0]+"|").getBytes("US-ASCII")));
}
private void accept(SelectionKey key) throws IOException {
ServerSocketChannel serverChannel = (ServerSocketChannel) key.channel();
SocketChannel channel = serverChannel.accept();
channel.configureBlocking(false);
// write welcome message
channel.write(ByteBuffer.wrap("Welcome, this is the echo server\r\n".getBytes("US-ASCII")));
Socket socket = channel.socket();
SocketAddress remoteAddr = socket.getRemoteSocketAddress();
log("Connected to: " + remoteAddr);
dataMap.put(channel, new ArrayList<byte[]>()); // register channel with selector for further IO
channel.register(this.selector, SelectionKey.OP_READ);
}
private void read(SelectionKey key) throws IOException {
SocketChannel channel = (SocketChannel) key.channel();
ByteBuffer buffer = ByteBuffer.allocate(8192);
int numRead = -1;
try {
numRead = channel.read(buffer);
}
catch (IOException e) {
e.printStackTrace();
}
if (numRead == -1) {
this.dataMap.remove(channel);
Socket socket = channel.socket();
SocketAddress remoteAddr = socket.getRemoteSocketAddress();
log("Connection closed by client: " + remoteAddr);
channel.close();
key.cancel();
return;
}
byte[] data = new byte[numRead];
System.arraycopy(buffer.array(), 0, data, 0, numRead);
log("Got: " + new String(data, "US-ASCII"));
doEcho(key, data); // write back to client
}
private void write(SelectionKey key) throws IOException {
SocketChannel channel = (SocketChannel) key.channel();
List<byte[]> pendingData = this.dataMap.get(channel);
Iterator<byte[]> items = pendingData.iterator();
while (items.hasNext()) {
byte[] item = items.next();
items.remove();
channel.write(ByteBuffer.wrap(item));
}
key.interestOps(SelectionKey.OP_READ);
}
private void doEcho(SelectionKey key, byte[] data) {
SocketChannel channel = (SocketChannel) key.channel();
List<byte[]> pendingData = this.dataMap.get(channel);
pendingData.add(data);
key.interestOps(SelectionKey.OP_WRITE);
}
private static void log(String s) {
System.out.println(s);
}
public static void main(String[] args) throws Exception {
new EchoServer(null, 8989);
}
}
The program works with incoming connections. 该程序适用于传入连接。 But when I make an outgoing connection, the program does not work. 但是当我进行传出连接时,该程序不起作用。 I need to make some connections in a row through the connect (String hostname, int port) and receive data in a method read(). 我需要通过connect(String hostname,int port)连续建立一些连接,并在方法read()中接收数据。 The program stops working on the line clientChannel.register(...) 该程序停止在clientChannel.register(...)行上工作
You need to check for a connectable key, eg 您需要检查可连接的密钥,例如
if (key.isConnectable()) {
this.doConnect(key);
}
...
private void doConnect(SelectionKey key) {
SocketChannel channel = (SocketChannel) key.channel();
if (channel.finishConnect()) {
/* success */
} else {
/* failure */
}
}
Use SocketChannel.finishConnect to determine whether the connection was established successfully. 使用SocketChannel.finishConnect确定连接是否已成功建立。
This is my NIO Client example Ive been using. 这是我一直在使用的NIO客户端示例。 It gives a timed out open/write/read functions and is suitable for request-response messaging. 它提供了超时的开放/写入/读取功能,适用于请求 - 响应消息传递。
Tricky part is always how do parties recognize a packet is fully received. 棘手的部分始终是各方如何识别数据包被完全接收。 This example assumes 这个例子假定
You could write 4-byte length header, fixed size packet splitter or delimiter 0x27 byte but make sure it cannot be a value of data payload. 您可以编写4字节长度的报头,固定大小的数据包拆分器或分隔符0x27字节,但要确保它不能是数据有效负载的值。 NIO read() or write() never assumes you receive a full packet in one call. NIO read()或write()从不假设您在一次调用中收到完整数据包。 Or may read two or more packet bytes in one read() buffer. 或者可以在一个read()缓冲区中读取两个或更多个包字节。 It is up to us make a packet parser not loosing bytes. 由我们来决定数据包解析器不会丢失字节。
import java.util.*;
import java.io.*;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
public class DPSocket {
private boolean debug;
private String host;
private int port;
private String charset;
private ByteArrayOutputStream inBuffer;
private ByteBuffer buf;
private Selector selector;
private SocketChannel channel;
public DPSocket(String host, int port, String charset) {
this.charset = charset==null || charset.equals("") ? "UTF-8" : charset;
this.host = host;
this.port = port;
}
public boolean isDebug() { return debug; }
public void setDebug(boolean b) { debug=b; }
public void open(long timeout) throws IOException {
selector = Selector.open();
channel = SocketChannel.open();
channel.configureBlocking(false);
channel.register(selector, SelectionKey.OP_CONNECT);
channel.connect(new InetSocketAddress(host, port));
inBuffer = new ByteArrayOutputStream(1024);
buf = ByteBuffer.allocate(1*1024);
long sleep = Math.min(timeout, 1000);
while(timeout > 0) {
if (selector.select(sleep) < 1) {
timeout-=sleep;
continue;
}
Iterator<SelectionKey> keys = selector.selectedKeys().iterator();
while(keys.hasNext()) {
SelectionKey key = keys.next();
keys.remove();
if (!key.isValid() || !key.isConnectable()) continue;
SocketChannel channel = (SocketChannel)key.channel();
if (channel.isConnectionPending()) {
channel.finishConnect();
channel.configureBlocking(false);
if (debug) System.out.println("finishConnect");
return; // we are ready to receive bytes
}
}
}
throw new IOException("Connection timed out");
}
public void close() {
try { if(channel!=null) channel.close(); } catch(Exception ex) { }
try { if(selector!=null) selector.close(); } catch(Exception ex) { }
inBuffer=null;
buf=null;
}
public void write(String data, long timeout) throws IOException {
write(data.getBytes(charset), timeout);
}
public void write(byte[] bytes, long timeout) throws IOException {
ByteBuffer outBuffer = ByteBuffer.wrap(bytes);
channel.register(selector, SelectionKey.OP_WRITE);
long sleep = Math.min(timeout, 1000);
while(timeout > 0) {
if (selector.select(sleep) < 1) {
timeout-=sleep;
continue;
}
Iterator<SelectionKey> keys = selector.selectedKeys().iterator();
while(keys.hasNext()) {
SelectionKey key = keys.next();
keys.remove();
if (!key.isValid() || !key.isWritable()) continue;
SocketChannel channel = (SocketChannel)key.channel();
if (debug) System.out.println("write remaining="+outBuffer.remaining());
channel.write(outBuffer);
if (debug) System.out.println("write remaining="+outBuffer.remaining());
if (outBuffer.remaining()<1)
return;
}
}
throw new IOException("Write timed out");
}
public List<String> readUntil(String terminator, long timeout, boolean trimLines) throws IOException {
return readUntil(new String[]{terminator}, timeout, trimLines);
}
public List<String> readUntil(String[] terminators, long timeout, boolean trimLines) throws IOException {
List<String> lines = new ArrayList<String>(12);
inBuffer.reset();
// End of packet terminator strings, line startsWith "aabbcc" string.
byte[][] arrTerminators = new byte[terminators.length][];
int[] idxTerminators = new int[terminators.length];
for(int idx=0; idx < terminators.length; idx++) {
arrTerminators[idx] = terminators[idx].getBytes(charset);
idxTerminators[idx] = 0;
}
int idxLineByte=-1;
channel.register(selector, SelectionKey.OP_READ);
long sleep = Math.min(timeout, 1000);
while(timeout>0) {
if (selector.select(sleep) < 1) {
timeout-=sleep;
continue;
}
Iterator<SelectionKey> keys = selector.selectedKeys().iterator();
while(keys.hasNext()) {
SelectionKey key = keys.next();
keys.remove();
if (!key.isValid() || !key.isReadable()) continue;
SocketChannel channel = (SocketChannel)key.channel();
buf.clear();
int len = channel.read(buf);
if (len == -1) throw new IOException("Socket disconnected");
buf.flip();
for(int idx=0; idx<len; idx++) {
byte cb = buf.get(idx);
if (cb!='\n') {
idxLineByte++;
inBuffer.write(cb);
for(int idxter=0; idxter < arrTerminators.length; idxter++) {
byte[] arrTerminator = arrTerminators[idxter];
if (idxLineByte==idxTerminators[idxter]
&& arrTerminator[ idxTerminators[idxter] ]==cb) {
idxTerminators[idxter]++;
if (idxTerminators[idxter]==arrTerminator.length)
return lines;
} else idxTerminators[idxter]=0;
}
} else {
String line = inBuffer.toString(charset);
lines.add(trimLines ? line.trim() : line);
inBuffer.reset();
idxLineByte=-1;
for(int idxter=0; idxter<arrTerminators.length; idxter++)
idxTerminators[idxter]=0;
}
}
}
}
throw new IOException("Read timed out");
}
// **************************
// *** test socket client ***
// **************************
public static void main(String[] args) throws Exception {
String NEWLINE = "\n";
int TIMEOUT=5000;
DPSocket dps = new DPSocket("myserver.com", 1234, "UTF-8");
dps.setDebug(true);
try {
List<String> lines;
dps.open(15000);
dps.write("Command1 arg1 arg2"+NEWLINE, TIMEOUT);
lines = dps.readUntil(">>", TIMEOUT, true);
dps.write("Command2 arg1 arg2"+NEWLINE, TIMEOUT);
lines = dps.readUntil(">>", TIMEOUT, true);
} catch (Exception ex) {
String msg = ex.getMessage();
if (msg==null) msg = ex.getClass().getName();
if (msg.contains("timed out") || msg.contains("Invalid command ")) {
System.out.println("ERROR: " + ex.getMessage());
} else {
System.out.print("ERROR: ");
ex.printStackTrace();
}
} finally {
dps.close();
}
}
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.