黑马程序员——网络编程总结

什么是网络编程？

网络编程建立在公共协议TCP/IP或者IOS协议的基础上，通过套接字的服务机制实现不同主机的联系。

 

网络编程的通讯要素

IP地址

网络中设备的识别，本地回环地址为127.0.0.1，主机名：localHost

端口号

用于标识不同进程的逻辑地址

传输协议

常用的协议是：UDP和TCP

 

获取主机网络地址对象

InetAddress  inetaddress1 = InetAddress.getByName("www.baidu.com")或者

InetAddress inetaddress2 = InetAddress.getByName("192.168.1.1"）

获取主机名

String hostname = inetaddress1.getHostName();

获取主机地址

String hostaddress = inetaddress1.getHostAddress();

 

套接字Socket

Socket是一种服务接口，它提供的服务能够实现数据包的传递

 

UDP协议特点

面向无连接，不可靠协议

数据报大小限制在64k内

传输速度快，容易丢包

TCP协议特点

面向连接，可靠协议，三次握手，建立连接

在连接中可进行大数据的传输

传输安全，速度慢

 

UDP传输

UDP发送数据报步骤：

1：建立DatagramSocket对象服务

DatagramSocket datagramsocket = new DatagramSocket();

2：建立数据报DatagramPacket对象

byte[] a = "hei ma cheng xu yuan".getBytes();

DatagramPacket  datagrampacket  = new DatagramPacket（a,a.length,InetAddress.getByName("192.168.1.1",10000);

3：发送数据包

datagramsocket.send(datagrampacket);

4:关闭Socket

datagramsocket.close();

UDP接收数据步骤

1：建立DatagramSocket对象服务

DatagramSocket datagramsocket = new DatagramSocket(10000);

2：建立数据报DatagramPacket对象

byte[] a = new byte[1024];

DatagramPacket  datagrampacket  = new DatagramPacket（a,a.length);

3：通过Socket服务的receive()方法把接收到的数据封装到已经准备好的数据包中

datagramsocket.receive();

4.通过接收到的数据包提供的方法，获取数据包中各种数据

返回主机对象

InetAddress inetaddress = a.getAddress();

获取主机名

String hostname = inetaddress1.getHostName();

获取主机地址

String hostaddress = inetaddress1.getHostAddress();

返回数据内容

byte[] data  = a.getData();

String b = new String(data,0,data.length());

返回端口号

int port  = a.getPort();

5,关闭Socket流

datagramsocket.close();

 

Tcp传输

Tcp客户端

1：建立套接字服务

Socket socket = new Socket(InetAddress.getByName("192.168.1.1",10000);

2:获取流

OutputStream output = socket.getOutputStream();

3:通过输入流写入数据

byte[] data  = "ke hu duan qing qiu lian jie".getBytes();

int len = output.write(data);

4:关闭流

socket.close();

Tcp服务端

1：建立套接字服务,并监听端口

ServerSocket serversocket = new ServerSocket(10000);

2:获取连接过来的客户端对象

Socket socket = serversockt.accept();

3:获取客户端连接过来的流,并读取相关数据

InputStream  input  = socket .getInputStream();

byte[] data = new byte[1024];

int len = data.read(data);

4.关闭流

serversocket.close();

 

URL

什么是URL

其实就是表示网页地址的字符串

 

建立URL对象

URL url1 = new URL("https://www.baidu.com/");

URL url2 = new URL("https://192.168.1.254:8080/myweb/demo.html");

 

获取URL对象方法

url2.getFile();获取文件名

url2.getHost();获取主机名

url2.getPort();获取端口号

url2.getPath();获取路径

url2.getProtocol();获取协议

url2.getQuery();获取查询部

 

连接到服务端

URLconnection urlconnection = url2.openConnection();

练习
/*
 * 编写一个聊天程序，有收数据的部分，有发数据的部分
 */
package bolgtest;
import java.io.*;
import java.net.*;
public class UdpTest {
 public static void main(String[] args)throws Exception {
  DatagramSocket datagramsocket1 = new DatagramSocket();
  DatagramSocket datagramsocket2 = new DatagramSocket(10000);
 
  UdpSend send = new UdpSend(datagramsocket1);
  UdpReceive receive = new UdpReceive(datagramsocket2);
  Thread thread1 = new Thread(send);
  Thread thread2 = new Thread(receive);
  thread1.start();
  thread2.start();
 
 }
}
class UdpSend implements Runnable{
 private DatagramSocket datagramsocket = null;
 UdpSend(DatagramSocket socket){
  this.datagramsocket = socket;
 }
 public void run(){
  BufferedReader buffer = null;
   try{
     buffer = new BufferedReader(new InputStreamReader(System.in));
    String str = null;
    while( (str = buffer.readLine())!=null)
    {
     if("886".equals(str))
      break;
     byte[] data = str.getBytes();
     DatagramPacket datagrampacket = new DatagramPacket(data,data.length,InetAddress.getByName("192.168.1.255"),10000);
     datagramsocket.send(datagrampacket);
    }
   }catch(Exception e){
    throw new RuntimeException("出错啦");
   }
   finally{
    try{
     buffer.close();
    }catch(Exception e){
     throw new RuntimeException("出错啦");
    }
   }
}
}
 
class UdpReceive implements Runnable{
 private DatagramSocket datagramsocket = null;
 UdpReceive(DatagramSocket socket){
  this.datagramsocket = socket;
 }
 public void run(){
  BufferedReader buffer = null;
  while(true){
   try{
    byte[] data = new byte[1024];
    DatagramPacket datagrampacket = new DatagramPacket(data,data.length);
    datagramsocket.receive(datagrampacket);
    String str = new String(datagrampacket.getData(),0,datagrampacket.getData().length);
    String str2 = datagrampacket.getAddress().getHostAddress();
    System.out.print(str2+":"+str);
   }catch(Exception e){
    throw new RuntimeException("出错啦");
   }
  }
   
   
   
  }
 }

练习
/*
 * 把客户端的一个文件传到服务端去，并且在服务端中存储起来
 */
package bolgtest;
import java.io.*;
import java.net.*;
public class ClientTest {
 public static void main(String[] args) {
  try{
   Socket socket = new Socket("192.168.1.101",10000);
   BufferedWriter buffwriter = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
   BufferedReader clientreader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
   BufferedReader buffread = new BufferedReader(new FileReader("F:\\BaiduYunDownload\\client.txt"));
   String str =null;
   while((str = buffread.readLine())!=null){
    buffwriter.write(str);
    buffwriter.newLine();
    buffwriter.flush();
   }
   socket.shutdownOutput();
   String str1 = null;
   while((str1 = clientreader.readLine())!=null){
    System.out.println(str1);
   }
  }catch(Exception e){
   System.out.println(e.getMessage());
  }
 
 
 
 }
}

package bolgtest;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
public class ServerTest {
 public static void main(String[] args)throws Exception {
  ServerSocket server = new ServerSocket(10000);
  Socket socket = server.accept();
  BufferedReader buffreader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
  BufferedWriter buffwriter = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
  PrintWriter printwriter = new PrintWriter(new FileWriter("F:\\BaiduYunDownload\\copy.txt"),true);
  String str = null;
  while((str = buffreader.readLine())!=null){
   printwriter.println(str);
  }
  buffwriter.write("上传成功");
  buffwriter.newLine();
  buffwriter.flush();
 
 }
}