网络编程

网络编程

IP地址

ip地址：inetAddress

• 唯一定位一台网络上的计算机

• 127.0.0.1：本机 localhost

• ip地址的分类

  • ipv4 四个字节组成 0-255

  • ipv6 128位 。八个无符号整数！

    2001:1ab2:cccc:0000:0015:1e2d:1314:22bb
    

  • 公网（互联网） 私网（局域网）

    • ABCD类地址
    • 192.168..xx.xx 专门给组织内部使用

public class Ip {
    public static void main(String[] args) {
        try {
            //查询本机地址
            InetAddress inetAddress1 = InetAddress.getByName("127.0.0.1");
            System.out.println(inetAddress1);
            InetAddress inetAddress3 = InetAddress.getByName("localhost");
            System.out.println(inetAddress3);
            InetAddress localHost = InetAddress.getLocalHost();
            System.out.println(localHost);
            //百度ip地址
            InetAddress inetAddress2 = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddress2);

        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
    }
}

端口

端口表示计算机上的一个程序的进程

• 不同的进程又不同的端口号！用来区分软件

• 被规定0-65535

• TCP / UDP ：65535 * 2 TCP:80 UDP:80 单个协议下端口号不能冲突，不同协议端口号可以相同

• 端口号分类

  • 公有端口0-1023

    • HTTP:80
    • HTTPS:443
    • FTP:21
    • Telent:23

  • 程序注册端口：1024-49151 分配和用户和程序

    • Tomcat：8080
    • MySQL:3306
    • Oracle：1521

  • 动态端口、私有端口：49152-65535

    netstat -ano #查看所有的端口
    netstat -ano|findstr ""  #查看指定的端口
    tasklist|findstr ""  #查看指定端口的进程
    

通信协议

协议：约定，就好比我现在说的普通话才能交流

网络通信协议：速率、传输码率、代码结构、传输控制

问题：非常的复杂？

大事化小：分层！

TCP/IP协议簇:实际上时一组协议

• 重要：
  • TCP：用户传输协议
  • UDP：用户数据报协议
• 出名的协议：
  • TCP
  • IP:网络互联协议

TCP UDP对比

TCP:打电话

• 连接、稳定
• 三次握手 四次挥手
  • A你愁啥？B瞅你咋地？A干一场！ 最少需要三次才能保证稳定连接
  • A我要走了 B你真的要走了么？ B你真的真的要走了么？ A我真的要走了
• 客户端、服务端
• 传输完成，释放连接、效率低

UDP: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，都可以发送
• 导弹
• DDOS：洪水攻击！饱和攻击

TCP实现聊天

客户端

1. 连接服务器 Socket
2. 发送消息

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

服务器

1. 建立服务端口 ServerSocket
2. 等待用户的连接 通过accept
3. 接受用户的消息

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

        }
    }
}

TCP文件上传实现

服务器端

public class TCPServer{
    public static void main(String[] args){
        ServerSocket serverSocket = null;
        Socket accept = null;//阻塞式监听，会一直等待客户端连接
        InputStream inputStream = null;
        FileOutputStream fileOutputStream = null;
        try {
            //创建服务
            serverSocket = new ServerSocket(9090);
            //监听客户端的连接
            accept = serverSocket.accept();
            //获取输入流
            inputStream = accept.getInputStream();
            //文件输出
            fileOutputStream = new FileOutputStream(new File("基础语法\\receive.jpg"));
            byte[] buffer = new byte[1024];
            int len;
            while ((len = inputStream.read(buffer)) != -1){
                fileOutputStream.write(buffer,0,len);
            }
            //通知客户端我接受完毕了
            OutputStream outputStream = accept.getOutputStream();
            outputStream.write("我接受完毕了，可以断开了".getBytes());
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //关闭资源
            try {
                if (fileOutputStream != null)
                    fileOutputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (inputStream != null)
                    inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (accept != null)
                    accept.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (serverSocket != null)
                    serverSocket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

客户端

public class TcpClient{
    public static void main(String[] args) {
        Socket socket = null;
        OutputStream outputStream = null;
        FileInputStream fileInputStream = null;
        InputStream inputStream = null;
        ByteArrayOutputStream byteArrayOutputStream = null;
        try {
            //建立Socket连接
            socket = new Socket(InetAddress.getByName("127.0.0.1"),9090);
            //创建一个输出流
            outputStream = socket.getOutputStream();
            //文件流
            //读取文件
            fileInputStream = new FileInputStream(new File("基础语法\\沙滩.jpg"));
            //写出文件
            byte[] buffer = new byte[1024];
            int len;
            while ((len = fileInputStream.read(buffer)) != -1){
                outputStream.write(buffer,0,len);
            }
            //通知服务器，我已经结束了
            socket.shutdownOutput();//我已经传输完了!
            //确定服务器接受完毕，才能断开连接
            inputStream = socket.getInputStream();
            byteArrayOutputStream = new ByteArrayOutputStream();
            byte[] buffer2= new byte[1024];
            int len2;
            while ((len2 = inputStream.read(buffer2)) != -1){
                byteArrayOutputStream.write(buffer2,0,len2);
            }
            System.out.println(byteArrayOutputStream.toString());
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //关闭资源
            try {
                if (byteArrayOutputStream!=null)
                byteArrayOutputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (inputStream!=null)
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (fileInputStream!=null)
                fileInputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (outputStream!=null)
                outputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (socket!=null)
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }

    }
}

Tomcat

服务端

• 自定义 S
• Tomcat服务器 S java后台开发！

客户端

• 自定义 C
• 浏览器 B

UDP

发短信：不用链接 需要知道对方的地址

发送消息

• 发送端

  //不需要连接服务器
  public class Demo {
      public static void main(String[] args) throws Exception {
          //建立一个Socket
          DatagramSocket datagramSocket = new DatagramSocket();
          //建个包
          String msg = "nihao";
          //发送给谁
          InetAddress localhost = InetAddress.getByName("localhost");
           int port = 9999;
           //数据  数据的长度起始  发送给谁
          DatagramPacket datagramPacket = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,localhost,port);
          //发送包
          datagramSocket.send(datagramPacket);
      }
  }
  

• 接收端

  等待客户端的连接
  public class Demo01 {
      public static void main(String[] args) throws Exception {
          //开放端口
          DatagramSocket datagramSocket = new DatagramSocket(9999);
          //接收数据  接受包
          byte[] buffer = new byte[1024];
          DatagramPacket datagramPacket = new DatagramPacket(buffer, 0, buffer.length);
  
          //阻塞接收
          datagramSocket.receive(datagramPacket);
  
          System.out.println(datagramPacket.getAddress().getHostAddress());
          System.out.println(new String(datagramPacket.getData(),0,datagramPacket.getLength()));
  
          //关闭连接
          datagramSocket.close();
      }
  

  循环发送消息

  public class Sender01 {
      public static void main(String[] args) throws Exception {
          DatagramSocket socket = new DatagramSocket(8888);
          //准备数据  控制台读取 System.in
          BufferedReader 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 (data.equals("bye")){
                  break;
              }
          }
          socket.close();
      }
  }
  

  循环接收消息

  public class Receicer01 {
      public static void main(String[] args) throws Exception {
          DatagramSocket socket = new DatagramSocket(6666);
          while (true){
              //准备接受包裹
              byte[] contain= new byte[1024];
              DatagramPacket packet = new DatagramPacket(contain,0,contain.length);
              socket.receive(packet);//阻塞式接受包裹
  
              //断开连接  bye
              byte[] data = packet.getData();
              String datas = new String(data,0,data.length);
              System.out.println(datas);
              if (datas.equals("bye")){
                  break;
              }
          }
          socket.close();
      }
  }
  

  在线咨询：两个人都可以是发送方，也都可以时接收方 多线程实现

  发送线程

  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();
          }
      }
      @Override
      public void run() {
          while (true){
              try {
                  String data = reader.readLine();
                  byte[] datas = data.getBytes();
                  DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress(this.toIp, this.toPort));
                  socket.send(packet);
                  if (data.equals("bye")){
                      break;
                  }
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          socket.close();
      }
  }
  

  接收线程

  public class TalkReceive implements Runnable {
      DatagramSocket socket = null;
      private int port;
      private String msgFrom;
      public TalkReceive(int port,String msgFrom) {
          this.port = port;
          this.msgFrom = msgFrom;
          try {
              socket = new DatagramSocket(port);
          } catch (SocketException e) {
              e.printStackTrace();
          }
      }
      @Override
      public void run() {
          while (true){
              try {
                  //准备接受包裹
                  byte[] contain= new byte[1024];
                  DatagramPacket packet = new DatagramPacket(contain,0,contain.length);
                  socket.receive(packet);//阻塞式接受包裹
                  //断开连接  bye
                  byte[] data = packet.getData();
                  String datas = new String(data,0,data.length);
                  System.out.println(msgFrom+":"+datas);
                  if (datas.equals("bye")){
                      break;
                  }
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          socket.close();
      }
  }
  

  学生端

  public class TalkStudent {
      public static void main(String[] args) {
          //开启两个线程
          new Thread(new TalkSend(7777,"localhost",9999)).start();
          new Thread(new TalkReceive(8888,"老师")).start();
      }
  }
  

  老师端

  public class TalkTeacher {
      public static void main(String[] args) {
          //开启两个线程
          new Thread(new TalkSend(5555,"localhost",8888)).start();
          new Thread(new TalkReceive(9999,"学生")).start();
      }
  }
  
  

  URL

  统一资源定位符:定位互联网上的某一个资源

  协议://ip地址:端口/项目名/资源
  

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

  下载网络资源

  public class Url {
      public static void main(String[] args) throws Exception {
          //下载地址
          URL url = new URL("http://localhost:8080/helloworld/index.jsp?username=qiu&password=123");
          //连接到这个资源  HTTP
  
          HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
          InputStream inputStream = urlConnection.getInputStream();
          FileOutputStream fileOutputStream = new FileOutputStream("基础语法\\abc.txt");
          byte[] buffer = new byte[1024];
          int len;
          while ((len = inputStream.read(buffer)) != -1){
              fileOutputStream.write(buffer,0,len);
          }
          fileOutputStream.close();
          inputStream.close();
          urlConnection.disconnect();
      }
  }
  

网络编程

原文：https://www.cnblogs.com/qiudajiang/p/13376882.html