#|NIO通信示例
【#|NIO通信示例】读者可以将代码拷贝到编译器上跑一跑,如果看了注释还有不懂的地方,可以参考:
NIO基础(一)之Buffer
NIO基础(二)之Channel
NIO基础(三)之Selector
第三篇尤为重要对看懂大体框架有很大意义。
public class Const {
public static int DEFAULT_PORT = 12345;
public static String DEFAULT_SERVER_IP = "127.0.0.1";
public static String response(String msg){
return "Hello,"+msg+",Now is "+new java.util.Date(
System.currentTimeMillis()).toString() ;
}
}
/**
* 类说明:nio通信客户端
*/
public class NioClient {
private static NioClientHandle nioClientHandle;
public static void start(){
if(nioClientHandle !=null)
nioClientHandle.stop();
nioClientHandle = new NioClientHandle(DEFAULT_SERVER_IP,DEFAULT_PORT);
new Thread(nioClientHandle,"Server").start();
}
//向服务器发送消息
public static boolean sendMsg(String msg) throws Exception{
nioClientHandle.sendMsg(msg);
return true;
}
public static void main(String[] args) throws Exception {
start();
Scanner scanner = new Scanner(System.in);
while(NioClient.sendMsg(scanner.next()));
}
}
/**
* 类说明:nio通信客户端处理器
*/
public class NioClientHandle implements Runnable{
private String host;
private int port;
private volatile boolean started;
private Selector selector;
private SocketChannel socketChannel;
public NioClientHandle(String ip, int port) {
this.host = ip;
this.port = port;
try {
/*创建选择器*/
this.selector = Selector.open();
/*打开监听通道*/
socketChannel = SocketChannel.open();
/*如果为 true,则此通道将被置于阻塞模式;
* 如果为 false,则此通道将被置于非阻塞模式
* 缺省为true*/
socketChannel.configureBlocking(false);
started = true;
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
}
public void stop(){
started = false;
}@Override
public void run() {
//连接服务器
try {
doConnect();
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
/*循环遍历selector*/
while(started){
try {
/*阻塞方法,当至少一个注册的事件发生的时候就会继续*/
selector.select();
/*获取当前有哪些事件可以使用*/
Set> keys = selector.selectedKeys();
/*转换为迭代器*/
Iterator> it = keys.iterator();
SelectionKey key = null;
while(it.hasNext()){
key = it.next();
/*我们必须首先将处理过的 SelectionKey 从选定的键集合中删除。
如果我们没有删除处理过的键,那么它仍然会在事件集合中以一个激活
的键出现,这会导致我们尝试再次处理它。*/
it.remove();
try {
handleInput(key);
} catch (Exception e) {
if(key!=null){
key.cancel();
if(key.channel()!=null){
key.channel().close();
}
}
}
}} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
}if(selector!=null){
try {
selector.close();
} catch (IOException e) {
e.printStackTrace();
}
}}/*具体的事件处理方法*/
private void handleInput(SelectionKey key) throws IOException {
if(key.isValid()){
/*获得关心当前事件的channel*/
SocketChannel sc =(SocketChannel)key.channel();
/*处理连接就绪事件
* 但是三次握手未必就成功了,所以需要等待握手完成和判断握手是否成功*/
if(key.isConnectable()){
/*finishConnect的主要作用就是确认通道连接已建立,
方便后续IO操作(读写)不会因连接没建立而
导致NotYetConnectedException异常。*/
if(sc.finishConnect()){
/*连接既然已经建立,当然就需要注册读事件,
写事件一般是不需要注册的。*/
socketChannel.register(selector,SelectionKey.OP_READ);
}else System.exit(-1);
}/*处理读事件,也就是当前有数据可读*/
if(key.isReadable()){
/*创建ByteBuffer,并开辟一个1k的缓冲区*/
ByteBuffer buffer = ByteBuffer.allocate(1024);
/*将通道的数据读取到缓冲区,read方法返回读取到的字节数*/
int readBytes = sc.read(buffer);
if(readBytes>0){
buffer.flip();
byte[] bytes = new byte[buffer.remaining()];
buffer.get(bytes);
String result = new String(bytes,"UTF-8");
System.out.println("客户端收到消息:"+result);
}
/*链路已经关闭,释放资源*/
else if(readBytes<0){
key.cancel();
sc.close();
}}
}
}/*进行连接*/
private void doConnect() throws IOException {
/*如果此通道处于非阻塞模式,则调用此方法将启动非阻塞连接操作。
如果连接马上建立成功,则此方法返回true。
否则,此方法返回false,
因此我们必须关注连接就绪事件,
并通过调用finishConnect方法完成连接操作。*/
if(socketChannel.connect(new InetSocketAddress(host,port))){
/*连接成功,关注读事件*/
socketChannel.register(selector,SelectionKey.OP_READ);
}
else{
socketChannel.register(selector,SelectionKey.OP_CONNECT);
}
}/*写数据对外暴露的API*/
public void sendMsg(String msg) throws IOException {
doWrite(socketChannel,msg);
}private void doWrite(SocketChannel sc,String request) throws IOException {
byte[] bytes = request.getBytes();
ByteBuffer writeBuffer = ByteBuffer.allocate(bytes.length);
writeBuffer.put(bytes);
writeBuffer.flip();
sc.write(writeBuffer);
}
}
/**
* 类说明:nio通信服务端
*/
public class NioServer {
private static NioServerHandle nioServerHandle;
public static void start(){
if(nioServerHandle !=null)
nioServerHandle.stop();
nioServerHandle = new NioServerHandle(DEFAULT_PORT);
new Thread(nioServerHandle,"Server").start();
}
public static void main(String[] args){
start();
}
}
/**
* 类说明:nio通信服务端处理器
*/
public class NioServerHandle implements Runnable{
private Selector selector;
private ServerSocketChannel serverChannel;
private volatile boolean started;
/**
* 构造方法
* @param port 指定要监听的端口号
*/
public NioServerHandle(int port) {
try{
//创建选择器
selector = Selector.open();
//打开监听通道
serverChannel = ServerSocketChannel.open();
//如果为 true,则此通道将被置于阻塞模式;
// 如果为 false,则此通道将被置于非阻塞模式
serverChannel.configureBlocking(false);
//开启非阻塞模式
serverChannel.socket().bind(new InetSocketAddress(port));
serverChannel.register(selector,SelectionKey.OP_ACCEPT);
//标记服务器已开启
started = true;
System.out.println("服务器已启动,端口号:" + port);
}catch(IOException e){
e.printStackTrace();
System.exit(1);
}
}
public void stop(){
started = false;
}@Override
public void run() {
//循环遍历selector
while(started){
try{
//阻塞,只有当至少一个注册的事件发生的时候才会继续.
selector.select();
Set> keys = selector.selectedKeys();
Iterator> it = keys.iterator();
SelectionKey key = null;
while(it.hasNext()){
key = it.next();
it.remove();
try{
handleInput(key);
}catch(Exception e){
if(key != null){
key.cancel();
if(key.channel() != null){
key.channel().close();
}
}
}
}
}catch(Throwable t){
t.printStackTrace();
}
}
//selector关闭后会自动释放里面管理的资源
if(selector != null)
try{
selector.close();
}catch (Exception e) {
e.printStackTrace();
}
}
private void handleInput(SelectionKey key) throws IOException{
if(key.isValid()){
//处理新接入的请求消息
if(key.isAcceptable()){
ServerSocketChannel ssc = (ServerSocketChannel)key.channel();
SocketChannel sc = ssc.accept();
System.out.println("=======建立连接===");
sc.configureBlocking(false);
sc.register(selector,SelectionKey.OP_READ);
}//读消息
if(key.isReadable()){
System.out.println("======socket channel 数据准备完成," +
"可以去读==读取=======");
SocketChannel sc = (SocketChannel) key.channel();
//创建ByteBuffer,并开辟一个1M的缓冲区
ByteBuffer buffer = ByteBuffer.allocate(1024);
//读取请求码流,返回读取到的字节数
int readBytes = sc.read(buffer);
//读取到字节,对字节进行编解码
if(readBytes>0){
//将缓冲区当前的limit设置为position,position=0,
// 用于后续对缓冲区的读取操作
buffer.flip();
//根据缓冲区可读字节数创建字节数组
byte[] bytes = new byte[buffer.remaining()];
//将缓冲区可读字节数组复制到新建的数组中
buffer.get(bytes);
String message = new String(bytes,"UTF-8");
System.out.println("服务器收到消息:" + message);
//处理数据
String result = response(message) ;
//发送应答消息
doWrite(sc,result);
}
//链路已经关闭,释放资源
else if(readBytes<0){
key.cancel();
sc.close();
}
}
}
}
//发送应答消息
private void doWrite(SocketChannel channel,String response)
throws IOException {
//将消息编码为字节数组
byte[] bytes = response.getBytes();
//根据数组容量创建ByteBuffer
ByteBuffer writeBuffer = ByteBuffer.allocate(bytes.length);
//将字节数组复制到缓冲区
writeBuffer.put(bytes);
//flip操作
writeBuffer.flip();
//发送缓冲区的字节数组
channel.write(writeBuffer);
}
}
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