利用java写一个TCP简单的客户端和服务端

TCPClient.java 

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

public class TCPClient {
	public static void main(String[] args) {
		InetAddress serverIP = null;
		Socket socket = null;
		OutputStream oStream = null;
		try {
			//客户端,获取IP地址
			serverIP = InetAddress.getByName("127.0.0.1");
			int port = 9999;
			//创建socket连接
			socket = new Socket(serverIP, port);
			//发送消息IO流
			oStream = socket.getOutputStream();
			//getBytes()方法是得到一个操作系统默认的编码格式的字节数组。
			oStream.write("hello".getBytes());
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			if(oStream!=null) {
				try {
					oStream.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			if (socket!=null){
				try {
					socket.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
	}

}

ServerClient.java

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class ServerClient {
	
	public static void main(String[] args) {
		ServerSocket serverSocket = null;
		Socket socket =	null;
		InputStream is = null;
		ByteArrayOutputStream baos = null;
		try {
			//目标地址
			serverSocket = new ServerSocket(9999);
			//等待客户端连接过来
			socket = serverSocket.accept();
			//读取客户端信息
			is = socket.getInputStream();
			//管道流
			baos = new ByteArrayOutputStream();
			byte[] buffer = new byte[1024];
			int len;
			while((len=is.read(buffer))!=-1) {
				baos.write(buffer, 0, len);
			}
			System.out.println(baos.toString());
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			if(baos!=null) {
				try {
					baos.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			if(is!=null) {
				try {
					is.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			if(socket!=null) {
				try {
					socket.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			if(serverSocket!=null) {
				try {
					serverSocket.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
	}
}