1.阻塞式
服务器端：
ServerSocketserverSocket = new ServerSocket(8888,10);
while(true)
{
Socket socket= serverSocket. accept();
Inpustream inpustream =socket.getInpustream();
Outpustream outpustream = socket.getOutpustream();
。。。。。
socket.close();
}
客户端：
Sockt socket = newSocket("10.1.2.11",8888);
Inpustream inpustream =socket.getInpustream();
Outpustream outpustream = socket.getOutpustream();
。。。。。
socket.close();
发生阻塞的地方：
客户端：
（1）请求与服务器建立连接时，执行connect方法，进入阻塞状态，直到连接成功
（2）从输入流读入数据，若无足够数据，进入阻塞，直到读到足够数据或到达末尾
（3）向输出流写数据，直到写完
（4）设置了关闭延迟时间，关闭后阻塞
服务器端：
（1）执行accept方法，等待客户端连接，进入阻塞，直到收到连接
（2）输入流读取数据，若没有足够数据，阻塞
（3）输出流写数据，进入阻塞，直到写完
多线程处理阻塞的局限
（1）线程多，开销大，增加JVM调度线程的负担，增加死锁可能性
（2）线程许多时间浪费在I/O上
2.非阻塞
服务器端：
Selector selector = Selector .open();
ServerSocketChannel serverSocketChannel =ServerSocketChannel. open();
serverSocketChannel. socket().setReuseAddress(true);
serverSocketChannel. configureBlocking(false);
serverSocketChannel. socket(). bind(newInetSocketAddress(8888));
serverSocketChannel. register(selector,SelectionKey. OP_ACCEPT);
while (selector. select() > 0) {
Set<<b>SelectionKey>selectedKeys = selector. selectedKeys();
Iterator iterator =selectedKeys.iterator();
while(iterator.hasNext()) {
SelectionKey key =null;
try {
key = iterator.next();
if (key. isAcceptable()) {
accept(key, selector);
} else if (key. isReadable()) {
receive(key);
} else if (key. isWritable()) {
send(key);
}
iterator.remove();
} catch(Exception ex) {
if (key != null) {
try{
key.cancel();
key.channel().close();
} catch (Exception ex2) {}
}
}
}
}
protected void accept(SelectionKey key, Selector selector) throws IOException {
ServerSocketChannel serverSocketChannel =(ServerSocketChannel) key. channel();
SocketChannel socketChannel =serverSocketChannel. accept();
socketChannel. configureBlocking(false);
ByteBuffer buffer =ByteBuffer. allocate(1024);
socketChannel. register(selector,SelectionKey. OP_READ | SelectionKey. OP_WRITE, buffer);
}
protected voidreceive(SelectionKey key) throws IOException {
ByteBuffer buffer = (ByteBuffer)key. attachment();
SocketChannel channel = (SocketChannel)key. channel();
ByteBuffer readBuffer =ByteBuffer.allocate(32);
channel. read(readBuffer);
readBuffer.flip();
buffer.limit(buffer.capacity());
buffer.put(readBuffer);//
System.out.println(Charset.forName("UTF-8"). decode(readBuffer).toString());
}
protected void send(SelectionKey key) throws IOException{
ByteBuffer buffer = (ByteBuffer)key. attachment();
SocketChannel channel = (SocketChannel)key. channel();
buffer.flip();
String data =Charset.forName("UTF-8").decode(buffer).toString();
if (data.indexOf("\r\n") == -1) {
return;
}
String str = data.substring(0,data.indexOf("\n") + 1);
ByteBuffer outBuffer =Charset.forName("UTF-8"). encode(" encode: " + str);
while (outBuffer. hasRemaining()) {
channel. write(outBuffer);
}
buffer.position(Charset.forName("UTF-8").encode(str).limit());
buffer.compact();
if ("bye\r\n".equals(str)) {
key. cancel();
key.channel(). close();
System.out.println(" close connection ");
}
}
客户端：
Selector selector= Selector .open();
SocketChannel socketChannel= SocketChannel. open();
InetSocketAddress address = newInetSocketAddress(InetAddress.getLocalHost(), 8888);
socketChannel. connect(address);
socketChannel. configureBlocking(false);
socketChannel. register(selector, SelectionKey. OP_READ |SelectionKey. OP_WRITE);
while (selector. select() > 0) {
Set<<b>SelectionKey>selectedKeys = selector. selectedKeys();
Iterator iterator =selectedKeys.iterator();
while(iterator.hasNext()) {
SelectionKey key =null;
try {
key = iterator.next();
if (key. isReadable()) {
receive(key);
} else if (key. isWritable()) {
send(key);
}
iterator.remove();
} catch(Exception ex) {
if (key != null) {
try{
key.cancel();
key.channel().close();
} catch (Exception ex2) {}
}
}
}
}
3.非阻塞方式提升性能方式
java.nio.Buffer 缓冲区提升I/O
（1）减少实际物理读写次数
（2）缓冲区内存复用，减少动态分配与回收次数
主要方法:
clear() 将极限设置为容量，位置置0
flip() 将极限设置为位置，位置置0
rewind() 极限不变，位置置0
（也就是说，改变的都是极限，位置都置0）
Selector 轮询方式：
（1）线程接收客户连接时，若无连接，则立即返回
（2）线程从输入流读取数据时，若无足够数据，读取现有数据，立即返回
（3）输出类似
混用非阻塞和多线程：一个线程用于接收连接，另一个线程用于读取数据和发送数据