Socket编程

BIO网络编程

BIO Server

package com.study.hc.net.bio;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket; public class BIOServer { public static void main(String[] args) throws Exception {
ServerSocket serverSocket = new ServerSocket(8080);
System.out.println("服务器启动成功");
while (!serverSocket.isClosed()) {
Socket request = serverSocket.accept();// 阻塞
System.out.println("收到新连接 : " + request.toString());
try {
// 接收数据、打印
InputStream inputStream = request.getInputStream(); // net + i/o
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "utf-8"));
String msg;
while ((msg = reader.readLine()) != null) { // 没有数据,阻塞
if (msg.length() == 0) {
break;
}
System.out.println(msg);
}
System.out.println("收到数据,来自:"+ request.toString());
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
request.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
serverSocket.close();
}
}

BIO Client

package com.study.hc.net.bio;

import java.io.OutputStream;
import java.net.Socket;
import java.nio.charset.Charset;
import java.util.Scanner; public class BIOClient {
private static Charset charset = Charset.forName("UTF-8"); public static void main(String[] args) throws Exception {
Socket s = new Socket("localhost", 8080);
OutputStream out = s.getOutputStream(); Scanner scanner = new Scanner(System.in);
System.out.println("请输入:");
String msg = scanner.nextLine();
out.write(msg.getBytes(charset)); // 阻塞,写完成
scanner.close();
s.close();
} }

当开启多个client的时候,则不能继续执行会卡在reader.readline()里面,因此是阻塞IO,直到第一个client发送完数据

升级成多线程版本

BIO Server

package com.study.hc.net.bio;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
// 多线程支持
public class BIOServer1 {
private static ExecutorService threadPool = Executors.newCachedThreadPool(); public static void main(String[] args) throws Exception {
ServerSocket serverSocket = new ServerSocket(8080);
System.out.println("tomcat 服务器启动成功");
while (!serverSocket.isClosed()) {
Socket request = serverSocket.accept();
System.out.println("收到新连接 : " + request.toString());
threadPool.execute(() -> {
try {
// 接收数据、打印
InputStream inputStream = request.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "utf-8"));
String msg;
while ((msg = reader.readLine()) != null) { // 阻塞
if (msg.length() == 0) {
break;
}
System.out.println(msg);
}
System.out.println("收到数据,来自:"+ request.toString());
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
request.close();
} catch (IOException e) {
e.printStackTrace();
}
}
});
}
serverSocket.close();
}
}

用浏览器试一下

加个状态码可以正常访问页面了,这个是HTTP

package com.study.hc.net.bio;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors; public class BIOServer2 { private static ExecutorService threadPool = Executors.newCachedThreadPool(); public static void main(String[] args) throws Exception {
ServerSocket serverSocket = new ServerSocket(8080);
System.out.println("服务器启动成功");
while (!serverSocket.isClosed()) {
Socket request = serverSocket.accept();
System.out.println("收到新连接 : " + request.toString());
threadPool.execute(() -> {
try {
// 接收数据、打印
InputStream inputStream = request.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "utf-8"));
String msg;
while ((msg = reader.readLine()) != null) {
if (msg.length() == 0) {
break;
}
System.out.println(msg);
} System.out.println("收到数据,来自:"+ request.toString());
// 响应结果 200
OutputStream outputStream = request.getOutputStream();
outputStream.write("HTTP/1.1 200 OK\r\n".getBytes());
outputStream.write("Content-Length: 11\r\n\r\n".getBytes());
outputStream.write("Hello World".getBytes());
outputStream.flush();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
request.close();
} catch (IOException e) {
e.printStackTrace();
}
}
});
}
serverSocket.close();
}
}

NIO网络编程

只是一个API

package com.study.hc.net.nio;

import java.nio.ByteBuffer;
import java.nio.IntBuffer;
import java.nio.LongBuffer; public class BufferDemo {
public static void main(String[] args) {
// 构建一个byte字节缓冲区,容量是4
ByteBuffer byteBuffer = ByteBuffer.allocateDirect(4);
// 默认写入模式,查看三个重要的指标
System.out.println(String.format("初始化:capacity容量:%s, position位置:%s, limit限制:%s", byteBuffer.capacity(),
byteBuffer.position(), byteBuffer.limit()));
// 写入2字节的数据
byteBuffer.put((byte) 1);
byteBuffer.put((byte) 2);
byteBuffer.put((byte) 3);
// 再看数据
System.out.println(String.format("写入3字节后,capacity容量:%s, position位置:%s, limit限制:%s", byteBuffer.capacity(),
byteBuffer.position(), byteBuffer.limit())); // 转换为读取模式(不调用flip方法,也是可以读取数据的,但是position记录读取的位置不对)
System.out.println("#######开始读取");
byteBuffer.flip();
byte a = byteBuffer.get();
System.out.println(a);
byte b = byteBuffer.get();
System.out.println(b);
System.out.println(String.format("读取2字节数据后,capacity容量:%s, position位置:%s, limit限制:%s", byteBuffer.capacity(),
byteBuffer.position(), byteBuffer.limit())); // 继续写入3字节,此时读模式下,limit=3,position=2.继续写入只能覆盖写入一条数据
// clear()方法清除整个缓冲区。compact()方法仅清除已阅读的数据。转为写入模式
byteBuffer.compact(); // buffer : 1 , 3
byteBuffer.put((byte) 3);
byteBuffer.put((byte) 4);
byteBuffer.put((byte) 5);
System.out.println(String.format("最终的情况,capacity容量:%s, position位置:%s, limit限制:%s", byteBuffer.capacity(),
byteBuffer.position(), byteBuffer.limit())); // rewind() 重置position为0
// mark() 标记position的位置
// reset() 重置position为上次mark()标记的位置 }
}

Cleaner是一个虚引用,回收堆外内存

package com.study.hc.net.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel; /**
* 直接基于非阻塞的写法
*/
public class NIOServer { public static void main(String[] args) throws Exception {
// 创建网络服务端
ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
serverSocketChannel.configureBlocking(false); // 设置为非阻塞模式
serverSocketChannel.socket().bind(new InetSocketAddress(8080)); // 绑定端口
System.out.println("启动成功");
while (true) {
SocketChannel socketChannel = serverSocketChannel.accept(); // 获取新tcp连接通道
// tcp请求 读取/响应
if (socketChannel != null) {
System.out.println("收到新连接 : " + socketChannel.getRemoteAddress());
socketChannel.configureBlocking(false); // 默认是阻塞的,一定要设置为非阻塞
try {
ByteBuffer requestBuffer = ByteBuffer.allocate(1024);
while (socketChannel.isOpen() && socketChannel.read(requestBuffer) != -1) {
// 长连接情况下,需要手动判断数据有没有读取结束 (此处做一个简单的判断: 超过0字节就认为请求结束了)
if (requestBuffer.position() > 0) break;
}
if(requestBuffer.position() == 0) continue; // 如果没数据了, 则不继续后面的处理
requestBuffer.flip();
byte[] content = new byte[requestBuffer.limit()];
requestBuffer.get(content);
System.out.println(new String(content));
System.out.println("收到数据,来自:"+ socketChannel.getRemoteAddress()); // 响应结果 200
String response = "HTTP/1.1 200 OK\r\n" +
"Content-Length: 11\r\n\r\n" +
"Hello World";
ByteBuffer buffer = ByteBuffer.wrap(response.getBytes());
while (buffer.hasRemaining()) {
socketChannel.write(buffer);// 非阻塞
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
// 用到了非阻塞的API, 在设计上,和BIO可以有很大的不同.继续改进
}
}
package com.study.hc.net.nio;

import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
import java.util.Scanner; public class NIOClient { public static void main(String[] args) throws Exception {
SocketChannel socketChannel = SocketChannel.open();
socketChannel.configureBlocking(false);
socketChannel.connect(new InetSocketAddress("127.0.0.1", 8080));
while (!socketChannel.finishConnect()) {
// 没连接上,则一直等待
Thread.yield();
}
Scanner scanner = new Scanner(System.in);
System.out.println("请输入:");
// 发送内容
String msg = scanner.nextLine();
ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
while (buffer.hasRemaining()) {
socketChannel.write(buffer);
}
// 读取响应
System.out.println("收到服务端响应:");
ByteBuffer requestBuffer = ByteBuffer.allocate(1024); while (socketChannel.isOpen() && socketChannel.read(requestBuffer) != -1) {
// 长连接情况下,需要手动判断数据有没有读取结束 (此处做一个简单的判断: 超过0字节就认为请求结束了)
if (requestBuffer.position() > 0) break;
}
requestBuffer.flip();
byte[] content = new byte[requestBuffer.limit()];
requestBuffer.get(content);
System.out.println(new String(content));
scanner.close();
socketChannel.close();
} }

该代码进入while循环判断读取是否完成,因此不能进行多个client连接

直接基于非阻塞的写法

package com.study.hc.net.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.ArrayList;
import java.util.Iterator; /**
* 直接基于非阻塞的写法,一个线程处理轮询所有请求
*/
public class NIOServer1 {
/**
* 已经建立连接的集合
*/
private static ArrayList<SocketChannel> channels = new ArrayList<>(); public static void main(String[] args) throws Exception {
// 创建网络服务端
ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
serverSocketChannel.configureBlocking(false); // 设置为非阻塞模式
serverSocketChannel.socket().bind(new InetSocketAddress(8080)); // 绑定端口
System.out.println("启动成功");
while (true) {
SocketChannel socketChannel = serverSocketChannel.accept(); // 获取新tcp连接通道
// tcp请求 读取/响应
if (socketChannel != null) {
System.out.println("收到新连接 : " + socketChannel.getRemoteAddress());
socketChannel.configureBlocking(false); // 默认是阻塞的,一定要设置为非阻塞
channels.add(socketChannel);
} else {
// 没有新连接的情况下,就去处理现有连接的数据,处理完的就删除掉
Iterator<SocketChannel> iterator = channels.iterator();
while (iterator.hasNext()) {
SocketChannel ch = iterator.next();
try {
ByteBuffer requestBuffer = ByteBuffer.allocate(1024); if (ch.read(requestBuffer) == 0) {
// 等于0,代表这个通道没有数据需要处理,那就待会再处理
continue;
}
while (ch.isOpen() && ch.read(requestBuffer) != -1) {
// 长连接情况下,需要手动判断数据有没有读取结束 (此处做一个简单的判断: 超过0字节就认为请求结束了)
if (requestBuffer.position() > 0) break;
}
if(requestBuffer.position() == 0) continue; // 如果没数据了, 则不继续后面的处理
requestBuffer.flip();
byte[] content = new byte[requestBuffer.limit()];
requestBuffer.get(content);
System.out.println(new String(content));
System.out.println("收到数据,来自:" + ch.getRemoteAddress()); // 响应结果 200
String response = "HTTP/1.1 200 OK\r\n" +
"Content-Length: 11\r\n\r\n" +
"Hello World";
ByteBuffer buffer = ByteBuffer.wrap(response.getBytes());
while (buffer.hasRemaining()) {
ch.write(buffer);
}
iterator.remove();
} catch (IOException e) {
e.printStackTrace();
iterator.remove();
}
}
}
}
// 用到了非阻塞的API, 再设计上,和BIO可以有很大的不同
// 问题: 轮询通道的方式,低效,浪费CPU
}
}

但还是低效的循环检查,虽然解决了while的阻塞等待的问题

package com.study.hc.net.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors; /**
* 结合Selector实现的非阻塞服务端(放弃对channel的轮询,借助消息通知机制)
*/
public class NIOServerV2 { public static void main(String[] args) throws Exception {
// 1. 创建网络服务端ServerSocketChannel
ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
serverSocketChannel.configureBlocking(false); // 设置为非阻塞模式 // 2. 构建一个Selector选择器,并且将channel注册上去
Selector selector = Selector.open();
SelectionKey selectionKey = serverSocketChannel.register(selector, 0, serverSocketChannel);// 将serverSocketChannel注册到selector
selectionKey.interestOps(SelectionKey.OP_ACCEPT); // 对serverSocketChannel上面的accept事件感兴趣(serverSocketChannel只能支持accept操作) // 3. 绑定端口
serverSocketChannel.socket().bind(new InetSocketAddress(8080)); System.out.println("启动成功"); while (true) {
// 不再轮询通道,改用下面轮询事件的方式.select方法有阻塞效果,直到有事件通知才会有返回
selector.select();
// 获取事件
Set<SelectionKey> selectionKeys = selector.selectedKeys();
// 遍历查询结果e
Iterator<SelectionKey> iter = selectionKeys.iterator();
while (iter.hasNext()) {
// 被封装的查询结果
SelectionKey key = iter.next();
iter.remove();
// 关注 Read 和 Accept两个事件
if (key.isAcceptable()) {
ServerSocketChannel server = (ServerSocketChannel) key.attachment();
// 将拿到的客户端连接通道,注册到selector上面
SocketChannel clientSocketChannel = server.accept(); // mainReactor 轮询accept
clientSocketChannel.configureBlocking(false);
clientSocketChannel.register(selector, SelectionKey.OP_READ, clientSocketChannel);
System.out.println("收到新连接 : " + clientSocketChannel.getRemoteAddress());
} if (key.isReadable()) {
SocketChannel socketChannel = (SocketChannel) key.attachment();
try {
ByteBuffer requestBuffer = ByteBuffer.allocate(1024);
while (socketChannel.isOpen() && socketChannel.read(requestBuffer) != -1) {
// 长连接情况下,需要手动判断数据有没有读取结束 (此处做一个简单的判断: 超过0字节就认为请求结束了)
if (requestBuffer.position() > 0) break;
}
if(requestBuffer.position() == 0) continue; // 如果没数据了, 则不继续后面的处理
requestBuffer.flip();
byte[] content = new byte[requestBuffer.limit()];
requestBuffer.get(content);
System.out.println(new String(content));
System.out.println("收到数据,来自:" + socketChannel.getRemoteAddress());
// TODO 业务操作 数据库 接口调用等等 // 响应结果 200
String response = "HTTP/1.1 200 OK\r\n" +
"Content-Length: 11\r\n\r\n" +
"Hello World";
ByteBuffer buffer = ByteBuffer.wrap(response.getBytes());
while (buffer.hasRemaining()) {
socketChannel.write(buffer);
}
} catch (IOException e) {
// e.printStackTrace();
key.cancel(); // 取消事件订阅
}
}
}
selector.selectNow();
}
// 问题: 此处一个selector监听所有事件,一个线程处理所有请求事件. 会成为瓶颈! 要有多线程的运用
}
}

package com.study.hc.net.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;
import java.util.Random;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.FutureTask;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.atomic.AtomicInteger; /**
* NIO selector 多路复用reactor线程模型
*/
public class NIOServerV3 {
/** 处理业务操作的线程 */
private static ExecutorService workPool = Executors.newCachedThreadPool(); /**
* 封装了selector.select()等事件轮询的代码
*/
abstract class ReactorThread extends Thread { Selector selector;
LinkedBlockingQueue<Runnable> taskQueue = new LinkedBlockingQueue<>(); /**
* Selector监听到有事件后,调用这个方法
*/
public abstract void handler(SelectableChannel channel) throws Exception; private ReactorThread() throws IOException {
selector = Selector.open();
} volatile boolean running = false; @Override
public void run() {
// 轮询Selector事件
while (running) {
try {
// 执行队列中的任务
Runnable task;
while ((task = taskQueue.poll()) != null) {
task.run();
}
selector.select(1000); // 获取查询结果
Set<SelectionKey> selected = selector.selectedKeys();
// 遍历查询结果
Iterator<SelectionKey> iter = selected.iterator();
while (iter.hasNext()) {
// 被封装的查询结果
SelectionKey key = iter.next();
iter.remove();
int readyOps = key.readyOps();
// 关注 Read 和 Accept两个事件
if ((readyOps & (SelectionKey.OP_READ | SelectionKey.OP_ACCEPT)) != 0 || readyOps == 0) {
try {
SelectableChannel channel = (SelectableChannel) key.attachment();
channel.configureBlocking(false);
handler(channel);
if (!channel.isOpen()) {
key.cancel(); // 如果关闭了,就取消这个KEY的订阅
}
} catch (Exception ex) {
key.cancel(); // 如果有异常,就取消这个KEY的订阅
}
}
}
selector.selectNow();
} catch (IOException e) {
e.printStackTrace();
}
}
} private SelectionKey register(SelectableChannel channel) throws Exception {
// 为什么register要以任务提交的形式,让reactor线程去处理?
// 因为线程在执行channel注册到selector的过程中,会和调用selector.select()方法的线程争用同一把锁
// 而select()方法实在eventLoop中通过while循环调用的,争抢的可能性很高,为了让register能更快的执行,就放到同一个线程来处理
FutureTask<SelectionKey> futureTask = new FutureTask<>(() -> channel.register(selector, 0, channel));
taskQueue.add(futureTask);
return futureTask.get();
} private void doStart() {
if (!running) {
running = true;
start();
}
}
} private ServerSocketChannel serverSocketChannel;
// 1、创建多个线程 - accept处理reactor线程 (accept线程)
private ReactorThread[] mainReactorThreads = new ReactorThread[1];
// 2、创建多个线程 - io处理reactor线程 (I/O线程)
private ReactorThread[] subReactorThreads = new ReactorThread[8]; /**
* 初始化线程组
*/
private void newGroup() throws IOException {
// 创建IO线程,负责处理客户端连接以后socketChannel的IO读写
for (int i = 0; i < subReactorThreads.length; i++) {
subReactorThreads[i] = new ReactorThread() {
@Override
public void handler(SelectableChannel channel) throws IOException {
// work线程只负责处理IO处理,不处理accept事件
SocketChannel ch = (SocketChannel) channel;
ByteBuffer requestBuffer = ByteBuffer.allocate(1024);
while (ch.isOpen() && ch.read(requestBuffer) != -1) {
// 长连接情况下,需要手动判断数据有没有读取结束 (此处做一个简单的判断: 超过0字节就认为请求结束了)
if (requestBuffer.position() > 0) break;
}
if (requestBuffer.position() == 0) return; // 如果没数据了, 则不继续后面的处理
requestBuffer.flip();
byte[] content = new byte[requestBuffer.limit()];
requestBuffer.get(content);
System.out.println(new String(content));
System.out.println(Thread.currentThread().getName() + "收到数据,来自:" + ch.getRemoteAddress()); // TODO 业务操作 数据库、接口...
workPool.submit(() -> {
}); // 响应结果 200
String response = "HTTP/1.1 200 OK\r\n" +
"Content-Length: 11\r\n\r\n" +
"Hello World";
ByteBuffer buffer = ByteBuffer.wrap(response.getBytes());
while (buffer.hasRemaining()) {
ch.write(buffer);
}
}
};
} // 创建mainReactor线程, 只负责处理serverSocketChannel
for (int i = 0; i < mainReactorThreads.length; i++) {
mainReactorThreads[i] = new ReactorThread() {
AtomicInteger incr = new AtomicInteger(0); @Override
public void handler(SelectableChannel channel) throws Exception {
// 只做请求分发,不做具体的数据读取
ServerSocketChannel ch = (ServerSocketChannel) channel;
SocketChannel socketChannel = ch.accept();
socketChannel.configureBlocking(false);
// 收到连接建立的通知之后,分发给I/O线程继续去读取数据
int index = incr.getAndIncrement() % subReactorThreads.length;
ReactorThread workEventLoop = subReactorThreads[index];
workEventLoop.doStart();
SelectionKey selectionKey = workEventLoop.register(socketChannel);
selectionKey.interestOps(SelectionKey.OP_READ);
System.out.println(Thread.currentThread().getName() + "收到新连接 : " + socketChannel.getRemoteAddress());
}
};
} } /**
* 初始化channel,并且绑定一个eventLoop线程
*
* @throws IOException IO异常
*/
private void initAndRegister() throws Exception {
// 1、 创建ServerSocketChannel
serverSocketChannel = ServerSocketChannel.open();
serverSocketChannel.configureBlocking(false);
// 2、 将serverSocketChannel注册到selector
int index = new Random().nextInt(mainReactorThreads.length);
mainReactorThreads[index].doStart();
SelectionKey selectionKey = mainReactorThreads[index].register(serverSocketChannel);
selectionKey.interestOps(SelectionKey.OP_ACCEPT);
} /**
* 绑定端口
*
* @throws IOException IO异常
*/
private void bind() throws IOException {
// 1、 正式绑定端口,对外服务
serverSocketChannel.bind(new InetSocketAddress(8080));
System.out.println("启动完成,端口8080");
} public static void main(String[] args) throws Exception {
NIOServerV3 nioServerV3 = new NIOServerV3();
nioServerV3.newGroup(); // 1、 创建main和sub两组线程
nioServerV3.initAndRegister(); // 2、 创建serverSocketChannel,注册到mainReactor线程上的selector上
nioServerV3.bind(); // 3、 为serverSocketChannel绑定端口
}
}

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