java聊天室及其改进

功能描述即分解步骤：

1.服务器端接收客户端消息

2.服务器接收并返回客户端消息

3.客户端可以通过键盘持续的发送消息并接收服务端返回的消息

4.服务器同时处理多个客户端请求

5。让聊天室内的人可以看到彼此的消息

服务器端代码

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class Server {

	private static final List<BufferedWriter> list = new ArrayList();
	private static final Object lock = new Object();//创建一把锁
	
	public static void start() throws Exception {
		ServerSocket ssocket = new ServerSocket(9000);//监听一个端口
		
		System.out.println("服务器开启。。。。。。。");
		
		while (true) {
			Socket client = ssocket.accept();//此时会发生阻塞，等待客户端连接进来
			System.out.println(">>>有新客户端连接进来");
			
			new Thread(new Runnable() {

				@Override
				public void run() {
					try {
						BufferedReader br = new BufferedReader(new InputStreamReader(client.getInputStream()));
						BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(client.getOutputStream()));		
						
						synchronized (lock) {
							//将新用户加入到集合里
							list.add(bw);				
						}
					
						String data = null;
						while (null != (data = br.readLine())) {
							
							Iterator<BufferedWriter> iterator = list.iterator();
							
							while (iterator.hasNext()) {
								BufferedWriter bufw = iterator.next();
								try {
									bufw.write(data);
									bufw.newLine();
									bufw.flush();
								}catch (Exception e) {
									synchronized (lock) {
										iterator.remove();
									}
								}			
							}
						}
					} catch(Exception e) {
						e.printStackTrace();
					}				
				}
			}).start();;
		}	
	}
	
	public static void main(String[] args) throws Exception {
		Server.start();
	}
}

客户端代码

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;

public class Client {

	public static void start() throws Exception {
		String ip = "localhost";
		int port = 9000;
		
		Socket socket = new Socket(ip,port);
		
		//负责读取键盘输入的消息并发送给服务器端
		new Thread(new  Runnable() {

			@Override
			public void run() {
				try {
					BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
					BufferedReader keyIn = new BufferedReader(new InputStreamReader(System.in));//通过键盘进行输入	
					String msg = null;
			
					while (null != (msg = keyIn.readLine())) {
						bw.write(msg);
						bw.newLine();//添加换行
						bw.flush();
					}
				}catch (Exception e) {
					e.printStackTrace();
				}
			}	
		},"clientWriter").start();
		
		//负责读取服务端发送的消息
		new Thread(new Runnable() {

			@Override
			public void run() {
				try {
					BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
					String data = null;
					while (null != (data = br.readLine())) {
						System.out.println(">>>>" + data);
					}
				} catch(Exception e) {
					e.printStackTrace();
				}	
			}		
		},"clientReader").start();
		
	}
	
	public static void main(String[] args) throws Exception {
		Client.start();
	}
}

总结：
    该聊天室的功能虽然简单，但是运用到的知识非常广泛。涉及到面向对象，集合，IO，多线程，网络编程等知识，几乎涵盖了javase的重要基础部分。非常值得学习。但是以上代码还是有优化的空间。根据JDK8新特性Lamda表达式，我们可以简化启动线程部分的代码块。优化部分的代码块如下所示

new Thread(() -> {
				    try {
					BufferedReader br = new BufferedReader(new InputStreamReader(client.getInputStream()));
					BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(client.getOutputStream()));		
					
					synchronized (lock) {
						//将新用户加入到集合里
						list.add(bw);				
					}
				
					String data = null;
					while (null != (data = br.readLine())) {
						
						Iterator<BufferedWriter> iterator = list.iterator();//通过迭代器来遍历集合
						
						while (iterator.hasNext()) {
							BufferedWriter bufw = iterator.next();
							try {
								bufw.write(data);
								bufw.newLine();
								bufw.flush();
							}catch (Exception e) {
								synchronized (lock) {
									iterator.remove();
								}
							}			
						}
					}
				} catch(Exception e) {
					e.printStackTrace();
				}				
			}).start();

//负责读取键盘输入的消息并发送给服务器端
		new Thread(() -> {
			try {
				BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
				BufferedReader keyIn = new BufferedReader(new InputStreamReader(System.in));//通过键盘进行输入	
				String msg = null;
		
				while (null != (msg = keyIn.readLine())) {
					bw.write(msg);
					bw.newLine();//添加换行
					bw.flush();
				}
			}catch (Exception e) {
				e.printStackTrace();
			}	
		},"clientWriter").start();
		
		//负责读取服务端发送的消息
		new Thread(() -> {
			try {
				BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
				String data = null;
				while (null != (data = br.readLine())) {
					System.out.println(">>>>" + data);
				}
			} catch(Exception e) {
				e.printStackTrace();
			}			
	},"clientReader").start();