一、使用NIO完成网络通信的三个核心
1、通道（Channel）:负责连接
java.nio.channels.Channel 接口
|– SelectableChannel
|– SocketChannel
|–ServerChannel
|–DatagramChannel
|–Pipe.SinkChannel
|–Pipe.SourceChannel
2、缓冲区（Buffer）: 负责数据的存取
3、选择器（Selector）: 是SelectableChannel 的多路复用器，用于监控SelectableChannel 的IO状况
阻塞
1package nio; 2 3import java.io.IOException; 4import java.net.InetSocketAddress; 5import java.nio.ByteBuffer; 6import java.nio.channels.FileChannel; 7import java.nio.channels.ServerSocketChannel; 8import java.nio.channels.SocketChannel; 9import java.nio.file.Paths; 10import java.nio.file.StandardOpenOption; 11 12import org.junit.Test; 13 14public class TestBlockingNIO { 15 @Test 16 public void client() throws IOException{ 17 //1、获取通道 18 SocketChannel sChannel=SocketChannel.open(new InetSocketAddress("127.0.0.1",9898)); 19 FileChannel inChannel=FileChannel.open(Paths.get("1.jpg"), StandardOpenOption.READ); 20 //2、获取指定大小的缓冲区域 21 ByteBuffer buf=ByteBuffer.allocate(1024); 22 //3、读取本地文件，并发送到服务端去 23 while(inChannel.read(buf)!=-1){ 24 buf.flip(); 25 sChannel.write(buf); 26 buf.clear(); 27 } 28 //4、关闭通道 29 inChannel.close(); 30 sChannel.close(); 31 } 32 33 @Test 34 public void server() throws IOException{ 35 //1、获取通道 36 ServerSocketChannel ssChannel=ServerSocketChannel.open(); 37 FileChannel outChannel=FileChannel.open(Paths.get("2.jpg"),StandardOpenOption.WRITE,StandardOpenOption.CREATE); 38 //2、绑定连接 39 ssChannel.bind(new InetSocketAddress(9898)); 40 //3、获取客户端连接的通道 41 SocketChannel sChannel=ssChannel.accept(); 42 //4、分配指定大小的缓冲区 43 ByteBuffer buf=ByteBuffer.allocate(1024); 44 //5、接受客户端的数据，并保存到本地 45 while(sChannel.read(buf)!=-1){ 46 buf.flip(); 47 outChannel.write(buf); 48 buf.clear(); 49 } 50 //6、关闭通道 51 sChannel.close(); 52 ssChannel.close(); 53 outChannel.close(); 54 } 55}
非阻塞
1import java.io.IOException; 2import java.net.InetSocketAddress; 3import java.nio.ByteBuffer; 4import java.nio.channels.SelectionKey; 5import java.nio.channels.Selector; 6import java.nio.channels.ServerSocketChannel; 7import java.nio.channels.SocketChannel; 8import java.util.Date; 9import java.util.Iterator; 10import java.util.Scanner; 11 12import org.junit.Test; 13 14/* * 一、使用 NIO 完成网络通信的三个核心： * * 1. 通道（Channel）：负责连接 * * java.nio.channels.Channel 接口： * |--SelectableChannel * |--SocketChannel * |--ServerSocketChannel * |--DatagramChannel * * |--Pipe.SinkChannel * |--Pipe.SourceChannel * * 2. 缓冲区（Buffer）：负责数据的存取 * * 3. 选择器（Selector）：是 SelectableChannel 的多路复用器。用于监控 SelectableChannel 的 IO 状况 * */ 15public class TestNonBlockingNIO { 16 17 //客户端 18 @Test 19 public void client() throws IOException{ 20 //1. 获取通道 21 SocketChannel sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 9898)); 22 23 //2. 切换非阻塞模式 24 sChannel.configureBlocking(false); 25 26 //3. 分配指定大小的缓冲区 27 ByteBuffer buf = ByteBuffer.allocate(1024); 28 29 //4. 发送数据给服务端 30 Scanner scan = new Scanner(System.in); 31 32 while(scan.hasNext()){ 33 String str = scan.next(); 34 buf.put((new Date().toString() + "\n" + str).getBytes()); 35 buf.flip(); 36 sChannel.write(buf); 37 buf.clear(); 38 } 39 40 //5. 关闭通道 41 sChannel.close(); 42 } 43 44 //服务端 45 @Test 46 public void server() throws IOException{ 47 //1. 获取通道 48 ServerSocketChannel ssChannel = ServerSocketChannel.open(); 49 50 //2. 切换非阻塞模式 51 ssChannel.configureBlocking(false); 52 53 //3. 绑定连接 54 ssChannel.bind(new InetSocketAddress(9898)); 55 56 //4. 获取选择器 57 Selector selector = Selector.open(); 58 59 //5. 将通道注册到选择器上, 并且指定“监听接收事件” 60 ssChannel.register(selector, SelectionKey.OP_ACCEPT); 61 62 //6. 轮询式的获取选择器上已经“准备就绪”的事件 63 while(selector.select() > 0){ 64 65 //7. 获取当前选择器中所有注册的“选择键(已就绪的监听事件)” 66 Iterator<SelectionKey> it = selector.selectedKeys().iterator(); 67 68 while(it.hasNext()){ 69 //8. 获取准备“就绪”的是事件 70 SelectionKey sk = it.next(); 71 72 //9. 判断具体是什么事件准备就绪 73 if(sk.isAcceptable()){ 74 //10. 若“接收就绪”，获取客户端连接 75 SocketChannel sChannel = ssChannel.accept(); 76 77 //11. 切换非阻塞模式 78 sChannel.configureBlocking(false); 79 80 //12. 将该通道注册到选择器上 81 sChannel.register(selector, SelectionKey.OP_READ); 82 }else if(sk.isReadable()){ 83 //13. 获取当前选择器上“读就绪”状态的通道 84 SocketChannel sChannel = (SocketChannel) sk.channel(); 85 86 //14. 读取数据 87 ByteBuffer buf = ByteBuffer.allocate(1024); 88 89 int len = 0; 90 while((len = sChannel.read(buf)) > 0 ){ 91 buf.flip(); 92 System.out.println(new String(buf.array(), 0, len)); 93 buf.clear(); 94 } 95 } 96 97 //15. 取消选择键 SelectionKey 98 it.remove(); 99 } 100 } 101 } 102}