Java 网络 IO（BIO、NIO、AIO） - qidao123.com技术社区-IT企服评测·应用市场

import java.io.*;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;
public class BIOClient {
public static void main(String[] args) {
new BIOClient().start("localhost", 6666);
}
public void start(String host, int port) {
// 初始化 socket
Socket socket = new Socket();
try {
// 设置 socket 连接
SocketAddress remote = new InetSocketAddress(host, port);
socket.setSoTimeout(5000);
socket.connect(remote);
// 发送数据
PrintWriter writer = getWriter(socket);
writer.write("hello server");
writer.flush();
// // 发起请求
// PrintWriter writer = getWriter(socket);
// writer.write(compositeRequest(host));
// writer.flush();
//
// // 读取响应
// String msg;
// BufferedReader reader = getReader(socket);
// while ((msg = reader.readLine()) != null) {
// System.out.println(msg);
// }
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private BufferedReader getReader(Socket socket) throws IOException {
InputStream in = socket.getInputStream();
return new BufferedReader(new InputStreamReader(in));
}
private PrintWriter getWriter(Socket socket) throws IOException {
OutputStream out = socket.getOutputStream();
return new PrintWriter(new OutputStreamWriter(out));
}
private String compositeRequest(String host) {
return "GET / HTTP/1.1\r\n" +
"Host: " + host + "\r\n" +
"User-Agent: curl/7.43.0\r\n" +
"Accept: */*\r\n\r\n";
}
}

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import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class BIOServer {
public static void main(String[] args) throws Exception {
// 创建一个线程池
ExecutorService pool = Executors.newCachedThreadPool();
// 创建 ServerSocket
ServerSocket serverSocket = new ServerSocket(6666);
while (true) {
// 等待客户端连接
final Socket socket = serverSocket.accept();
// 接收到一个客户端连接放入线程池进行处理
pool.execute(() -> process(socket));
}
}
static void process(Socket socket) {
try {
byte[] bytes = new byte[1024];
// 通过 socket 获取输入流
InputStream inputStream = socket.getInputStream();
// 循环读取客户端发送的数据
while (true) {
// 没有数据的时候这里会阻塞等待
int read = inputStream.read(bytes);
if (read == -1) break;
// 输出客户端发送的数据
System.out.println(new String(bytes, 0, read));
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
socket.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}

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import java.io.RandomAccessFile;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
/**
* 说明 1.MappedByteBuffer 可让文件直接在内存（堆外内存）修改,操作系统不需要拷贝一次
*/
public class MappedByteBufferTest {
public static void main(String[] args) throws Exception {
RandomAccessFile randomAccessFile = new RandomAccessFile("1.txt", "rw");
//获取对应的通道
FileChannel channel = randomAccessFile.getChannel();
/**
* 参数 1:FileChannel.MapMode.READ_WRITE 使用的读写模式
* 参数 2：0：可以直接修改的起始位置
* 参数 3:5: 是映射到内存的大小（不是索引位置），即将 1.txt 的多少个字节映射到内存
* 可以直接修改的范围就是 0-5
* 实际类型 DirectByteBuffer
*/
MappedByteBuffer mappedByteBuffer = channel.map(FileChannel.MapMode.READ_WRITE, 0, 5);
mappedByteBuffer.put(0, (byte) 'H');
mappedByteBuffer.put(3, (byte) '9');
mappedByteBuffer.put(5, (byte) 'Y');//IndexOutOfBoundsException
randomAccessFile.close();
System.out.println("修改成功~~");
}
}

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import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;
public class GroupChatServer {
// 定义属性
private Selector selector;
private ServerSocketChannel listenChannel;
private static final int PORT = 6667;
// 构造器执行初始化工作
public GroupChatServer() {
try {
// 得到选择器
selector = Selector.open();
// 监听端口的主线程
listenChannel = ServerSocketChannel.open();
// 绑定端口
listenChannel.socket().bind(new InetSocketAddress(PORT));
// 设置非阻塞模式
listenChannel.configureBlocking(false);
// 将该 listenChannel 注册到 selector
listenChannel.register(selector, SelectionKey.OP_ACCEPT);
} catch (IOException e) {
e.printStackTrace();
}
}
public void listen() {
try {
// 循环处理
while (true) {
int count = selector.select();
// 有事件处理
if (count > 0) {
// 遍历得到 selectionKey 集合
Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
while (iterator.hasNext()) {
// 取出 selectionKey
SelectionKey key = iterator.next();
// 监听到 accept
if (key.isAcceptable()) {
SocketChannel sc = listenChannel.accept();
sc.configureBlocking(false);
// 将该 sc 注册到 selector
sc.register(selector, SelectionKey.OP_READ);
// 提示
System.out.println(sc.getRemoteAddress() + " 上线 ");
}
if (key.isReadable()) {// 通道发送read事件，即通道是可读的状态
// 处理读(专门写方法..)
readData(key);
}
// 当前的 key 删除，防止重复处理
iterator.remove();
}
} else {
System.out.println("等待....");
}
}
} catch (Exception e) {
e.printStackTrace();
} finally {
// 发生异常处理....
}
}
// 读取客户端消息
public void readData(SelectionKey key) {
SocketChannel channel = null;
try {
// 得到 channel
channel = (SocketChannel) key.channel();
// 创建 buffer
ByteBuffer buffer = ByteBuffer.allocate(1024);
int count = channel.read(buffer);// NIO这里不会阻塞因为事件触发时必然已经有数据了所以叫非阻塞IO
// 根据 count 的值做处理
if (count > 0) {
// 把缓存区的数据转成字符串
String msg = new String(buffer.array());
// 输出该消息
System.out.println("form客户端:" + msg);
// 向其它的客户端转发消息(去掉自己),专门写一个方法来处理
sendInfoToOtherClients(msg, channel);
}
} catch (IOException e) {
try {
System.out.println(channel.getRemoteAddress() + "离线了..");
// 取消注册
key.cancel();
// 关闭通道
channel.close();
} catch (IOException e2) {
e2.printStackTrace();
}
}
}
// 转发消息给其它客户(通道)
private void sendInfoToOtherClients(String msg, SocketChannel self) throws IOException {
System.out.println("服务器转发消息中...");
// 遍历所有注册到 selector 上的 SocketChannel,并排除 self
for (SelectionKey key : selector.keys()) {
// 通过 key 取出对应的 SocketChannel
Channel targetChannel = key.channel();
// 排除自己
if (targetChannel instanceof SocketChannel && targetChannel != self) {
// 转型
SocketChannel dest = (SocketChannel) targetChannel;
// 将 msg 存储到 buffer
ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
// 将 buffer 的数据写入通道
dest.write(buffer);
}
}
}
public static void main(String[] args) {
// 创建服务器对象
GroupChatServer groupChatServer = new GroupChatServer();
groupChatServer.listen();
}
}

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