IP地址

• IP地址：inet Address

• 唯一定位一台网络上的计算机

• 127.0.0.1：本机local hostipv

• IP地址的分类：

• ipv4：127.2.2.1,四个字节组成，0-255，大概有42亿；30亿在北美，亚洲4亿。

• IPv6: fe80::588c:5b23:d5c5:eed6%13，128位。

• 公网（互联网）——私网（局域网）

public class testInetAddress {public static void main(String[] args) {try {//查询本机地址InetAddress inetAddress = InetAddress.getByName("127.0.0.1");System.out.println(inetAddress);InetAddress inetAddress3 = InetAddress.getByName("localhost");System.out.println(inetAddress3);InetAddress inetAddress4 = InetAddress.getLocalHost();System.out.println(inetAddress4);//查询网站IP地址InetAddress inetAddress2 = InetAddress.getByName("www.baidu.com");System.out.println(inetAddress2);} catch (UnknownHostException e) {e.printStackTrace();}}

端口Port

端口表示计算机上的一个程序的进程

1. 不同的进程有不同的端口号，用来区分软件
2. 被规定0~65535
3. TCP，UDP：65535*2 单个协议下，端口号是不能冲突的
4. 端口分类

• 公有端口0~1023
• HTTP：80
• HTTPS：443
• FTP:21
• Telent:23

5. 程序注册端口：1024~49151，分配用户或者程序

• Tomcat：8080
• MySql：3306
• Oracle：1521

6. 动态，私有，

public class testSocketAddress {public static void main(String[] args) {InetSocketAddress socketAddress = new InetSocketAddress("127.0.0.1",8080);InetSocketAddress socketAddress2 = new InetSocketAddress("localhost",8080);System.out.println(socketAddress);System.out.println(socketAddress2);System.out.println(socketAddress.getAddress());System.out.println(socketAddress.getHostName());System.out.println(socketAddress.getPort());}

运行结果：

通信协议

1. 协议：就是约定，就好比我们现在所说的是普通话
2. 网络通信协议：速率，传输码率，代码结构，传输控制等等
3. TCP/IP协议簇：实际上就是一组协议，比较重要的是TCP和UDP，其中TCP是用户传输协议，UDP是用户数据报协议。比较出名的协议是TCP和IP，TCP是传输控制协议，IP是网络互联协议

TCP\IP 参考模型

TCP与UDP对比：
TCP和UDP协议是TCP/IP协议的核心。 TCP 传输协议：TCP 协议是一TCP (Transmission Control Protocol)和UDP(User Datagram Protocol)协议属于传输层协议。其中TCP提供IP环境下的数据可靠传输，它提供的服务包括数据流传送、可靠性、有效流控、全双工操作和多路复用。通过面向连接、端到端和可靠的数据包发送。通俗说，它是事先为所发送的数据开辟出连接好的通道，然后再进行数据发送；而UDP则不为IP提供可靠性、流控或差错恢复功能。一般来说，TCP对应的是可靠性要求高的应用，而UDP对应的则是可靠性要求低、传输经济的应用。

简单来说就是：
TCP相当与打电话，连接比较稳定，三次握手，四次挥手，客户端，服务端，传输完成，释放连接，效率较低。
UDP类似与发短信：不连接，不稳定，客户端服务端没有明确的界限。不管有没有准备好，都可以发给你

TCP

客户端
1.知道服务器的地址和端口号
2.连接服务器Socket
2.发送消息IO流

//客户端
public class TcpClictDemo1 {public static void main(String[] args) {Socket socket =null;OutputStream os =null;try {//1.要知道服务器的地址和端口号InetAddress byName = InetAddress.getByName("127.0.0.1");int port=9999;//2.创建一个socket连接socket = new Socket(byName,port);//3.发送消息，IO流os = socket.getOutputStream();os.write("你好".getBytes());} catch (Exception e) {e.printStackTrace();}finally {if (os!=null){try {os.close();} catch (IOException e) {e.printStackTrace();}}if (socket!=null){try {socket.close();} catch (IOException e) {e.printStackTrace();}}

服务器
1.建立服务的端口ServerSocket
2.等待用户的连接accept
3.接收消息

//服务端
public class TcpServerDemo1 {public static void main(String[] args) {ServerSocket serverSocket =null;Socket socket=null;InputStream is=null;ByteArrayOutputStream baos =null;try {//1.需要有一个地址serverSocket = new ServerSocket(9999);//2.等待客户端连接socket=serverSocket.accept();//3.读取客户端的信息is=socket.getInputStream();//4.管道流baos = new ByteArrayOutputStream();byte[] buffer=new byte[1024];int len;while ((len=is.read())!=-1){baos.write(buffer,0,len);}System.out.println(baos.toString());} catch (IOException e) {e.printStackTrace();}finally {if (serverSocket!=null){try {serverSocket.close();} catch (IOException e) {e.printStackTrace();}}if (socket!=null){try {socket.close();} catch (IOException e) {e.printStackTrace();}}if (is!=null){try {is.close();} catch (IOException e) {e.printStackTrace();}}if (baos!=null){try {baos.close();} catch (IOException e) {e.printStackTrace();}

TCP之文件图片的传输

//服务端
public class TcpServerDemo2 {public static void main(String[] args) throws Exception {//1.创建服务ServerSocket serverSocket = new ServerSocket(9000);//2.监听客户端的选择Socket socket = serverSocket.accept();//阻塞式监听，会一直等待客户端的连接//3.获取输入流InputStream is = socket.getInputStream();//4.文件输出FileOutputStream fos = new FileOutputStream(new File("receive.jpg"));byte[] buffer = new byte[1024];int len;while ((len=is.read(buffer))!=-1){fos.write(buffer,0,len);}//字符串//通知客户端接收完毕OutputStream os = socket.getOutputStream();os.write("已经接收完毕，可以断开了".getBytes());//5.关闭fos.close();is.close();socket.close();serverSocket.close();}
}

//客户端
public static void main(String[] args) throws Exception {//1.创建一个Socket连接Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9000);//2.创建一个输入流OutputStream os = socket.getOutputStream();//3.读取文件FileInputStream fis = new FileInputStream(new File("picture (10).jpg"));//4。写出文件byte[] bufffer=new byte[1024];int len;while ((len=fis.read(bufffer))!=-1){os.write(bufffer,0,len);}//通知服务器，我已经结束了socket.shutdownOutput();//我已经传输完毕了//字符串//确定接收完毕，才能断开连接InputStream inputStream = socket.getInputStream();//对应服务端的String byte[]ByteArrayOutputStream baos = new ByteArrayOutputStream();byte[] buffer2=new byte[1024];int len1;while ((len1=inputStream.read(buffer2))!=-1){baos.write(buffer2,0,len1);}System.out.println(baos.toString());//5.关闭资源baos.close();fis.close();os.close();socket.close();}
}

运行结果：

UDP

没有真正的服务端和客户端的连接，客户端相当于发快递，服务端相当于接收快递，父母知道我们的地址，给我们邮寄快递，我们在这个地方时刻准备着接收快递。

UDP消息发送

发送端

public static void main(String[] args) throws Exception {//1.建立一个SocketDatagramSocket socket = new DatagramSocket();//2.创建一个包String msg="你好，服务器！";//3.发送给谁InetAddress localhost=InetAddress.getByName("localhost");int port=9090;//发送数据：五个参数——>数据，数据的其实长度，数据的结束长度，要发给谁，端口号DatagramPacket packet = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,localhost,port);//4.发送包socket.send(packet);socket.close();}
}

接收端

public static void main(String[] args) throws Exception {//开放端口DatagramSocket socket = new DatagramSocket(9090);//接收数据包byte[] buffer = new byte[1024];DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);socket.receive(packet);//输出System.out.println(packet.getAddress().getHostAddress());System.out.println(new String(packet.getData(),0,packet.getLength()));socket.close();}
}

运行结果：

UDP基本聊天实现

发送方：

  public static void main(String[] args) throws Exception {DatagramSocket socket = new DatagramSocket(8888);//准备数据，控制台读取数据System.inBufferedReader reader = new BufferedReader(new InputStreamReader(System.in));while (true){String data = reader.readLine();byte [] datas=data.getBytes();DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress("localhost",6666));socket.send(packet);if (datas.equals("bye")){break;}}socket.close();}
}

接收方：

 public static void main(String[] args) throws Exception {DatagramSocket socket = new DatagramSocket(6666);while (true){//接收包裹byte [] container=new byte[1024];DatagramPacket packet = new DatagramPacket(container,0,container.length);socket.receive(packet);//阻塞式接收//断开连接 byebyte[] data = packet.getData();String receiveData =new String(data,0,data.length);System.out.println(receiveData);if (receiveData.equals("bye")){break;}}socket.close();

运行结果：

UDP多线程在线咨询

发送方：

public class TalkSend implements Runnable {DatagramSocket socket = null;BufferedReader reader = null;private int fromPort;private String toIP;private int toPort;public TalkSend(int fromPort, String toIP, int toPort) {this.fromPort = fromPort;this.toIP = toIP;this.toPort = toPort;try {socket = new DatagramSocket(fromPort);reader = new BufferedReader(new InputStreamReader(System.in));} catch (SocketException e) {e.printStackTrace();}}@Overridepublic void run() {//准备数据，控制台读取数据System.inwhile (true) {try {String data = reader.readLine();byte[] datas = data.getBytes();DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress(this.toIP, toPort));socket.send(packet);if (datas.equals("bye")) {break;}} catch (Exception e) {e.printStackTrace();}}socket.close();}
}

接收方：

 DatagramSocket socket=null;private int port;private String msgFrom;public TalkReceiveDemo(int port,String msgFrom) {this.port = port;this.msgFrom=msgFrom;try {socket=new DatagramSocket(port);} catch (SocketException e) {e.printStackTrace();}}@Overridepublic void run() {while (true){try{//接收包裹byte [] container=new byte[1024];DatagramPacket packet = new DatagramPacket(container,0,container.length);socket.receive(packet);//阻塞式接收//断开连接 byebyte[] data = packet.getData();String receiveData =new String(data,0,data.length);System.out.println(msgFrom+":"+receiveData);if (receiveData.equals("bye")){break;}}catch (Exception e){e.printStackTrace();}}socket.close();}

线程开启

//学生
public class TalkStudent {public static void main(String[] args) {new Thread(new TalkSend(7777,"localhost",9999)).start();new Thread(new TalkReceiveDemo(8888,"老师")).start();}
}
//老师
public class TalkTeacher {public static void main(String[] args) {new Thread(new TalkSend(5555,"localhost",8888)).start();new Thread(new TalkReceiveDemo(9999,"学生")).start();}
}

运行结果：

URL

URL的认识：

 public static void main(String[] args) throws MalformedURLException {URL url = new URL("http://localhost:8080/helloword/index.jsp?username=shmily&password=123");System.out.println(url.getProtocol());//协议System.out.println(url.getHost());//主机System.out.println(url.getPort());//端口System.out.println(url.getPath());//路径System.out.println(url.getFile());//文件System.out.println(url.getQuery());//参数}

运行结果：

下载网络资源：

public static void main(String[] args) throws Exception {//1.下载地址URL url = new URL("网址地址");//2.连接到这个资源的HTTPHttpURLConnection urlConnection =(HttpURLConnection) url.openConnection();InputStream inputStream = urlConnection.getInputStream();FileOutputStream fos = new FileOutputStream("下载后名字");byte[] buffer = new byte[1024];int len;while ((len=inputStream.read(buffer))!=-1){fos.write(buffer,0,len);}fos.close();inputStream.close();urlConnection.disconnect();//断开连接}
}