·功能:TCP客户端套接字
·构造方法: 
  Socket(InetAddress address, int port) 
  创建一个流套接字并将其连接到指定 IP 地址的指定端口号
·常用方法: 
  1.getInetAddress 
  获得InetAddress的相关信息
  2.getInputStream 
  获得此TCP连接的输入流
  3.getOutPutStream 
  获得此TCP连接的输出流

·功能: TCP服务端套接字
·构造方法: 
  ServerSocket(int port) 
  创建绑定到特定端口的服务器套接字。
·常用方法: 
  1.accept 
  获得TCP连接的客户端的socket
  2.isClosed 
  获得ServerSocket的关闭状态

package cn.xidian.tcpSocket;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
public class TcpServer extends Thread{
	Socket clientSocket;
	public TcpServer(Socket clientSocket) {
		super();
		this.clientSocket = clientSocket;
	}
	@Override
	  public void run() {
		try {
			//获得客户端的ip地址和主机名
			String clientAddress = clientSocket.getInetAddress().getHostAddress();
			String clientHostName = clientSocket.getInetAddress().getHostName();
			System.out.println(clientHostName + "(" + clientAddress + ")" + " 连接成功!");
			System.out.println("Now, 传输图片数据...........");
			long startTime = System.currentTimeMillis();
			//获取客户端的OutputStream
			OutputStream out = clientSocket.getOutputStream();
			//传出图片数据
			FileInputStream in = new FileInputStream(new File("/home/gavinzhou/test.jpg"));
			byte[] data = new byte[4096];
			int length = 0;
			while((length = in.read(data)) != -1){
				out.write(data, 0, length);
				//写出数据
			}
			long endTime = System.currentTimeMillis();
			//提示信息
			System.out.println(clientHostName + "(" + clientAddress + ")" + " 图片传输成功," + "用时:" + ((endTime-startTime)) + "ms");
			//关闭资源
			in.close();
			clientSocket.close();
			System.out.println("连接关闭!");
		}
		catch (IOException e) {
			e.printStackTrace();
		}
	}
	public static void main(String[] args) throws IOException {
		//建立TCP连接服务,绑定端口
		ServerSocket tcpServer = new ServerSocket(9090);
		//接受连接,传图片给连接的客户端,每个TCP连接都是一个java线程
		while(true){
			Socket clientSocket = tcpServer.accept();
			new TcpServer(clientSocket).start();
		}
	}
}

package cn.xidian.tcpSocket;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.InetAddress;
import java.net.Socket;
public class TcpClient {
	public static void main(String[] args) throws IOException {
		// 建立TCP服务
		// 连接本机的TCP服务器
		Socket socket = new Socket(InetAddress.getLocalHost(), 9090);
		// 获得输入流
		InputStream inputStream = socket.getInputStream();
		// 写入数据
		FileOutputStream out = new FileOutputStream(new File("../save.jpg"));
		byte[] data = new byte[4096];
		int length = 0;
		while((length = inputStream.read(data)) != -1){
			out.write(data, 0, length);
		}
		//关闭资源
		out.close();
		socket.close();
	}
}