网络编程

网络编程

1.三要素:

1>找到IP地址.

2>必须有端口.

3>必须有协议.(TCP,UDP)

TCP和UDP协议的区别:

TCP:(客户端和服务器的交互)

1>建立连接通道(通道内的流:使用最基本的字节流)

2>可靠协议.

3>执行效率低.

4>使用TCP协议可以发送大量的数据,文件大小无限制.

UDP:(发送端和接收端)

1>无需建立连接通道.

2>不可靠协议.

3>执行效率高.

4>发送数据有限.

UDP协议:

发送端:步骤:

1>创建UDP协议发送端的Socket对象.

2>创建数据报包:通过这个数据报包讲数据发送到接收端.

3>调用UDP协议发送端的send方法.

4>关闭资源.

相关代码:

import java.io.IOException;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.InetAddress;public class SendDemo {public static void main(String[] args) throws IOException {DatagramSocket ds=new DatagramSocket();byte[] bytes = "立华奏".getBytes();DatagramPacket dp = new DatagramPacket(bytes, bytes.length,InetAddress.getByName("10.201.18.230"), 10000);ds.send(dp);ds.close();}}

接收端:步骤:

1>创建UDP协议接收端的Socket对象.

2>创建数据报包:接受发送端发来的数据报包.

3>接受数据:调用接收端Socket对象的recive方法接收.

4>解析数据报包里的数据.getData方法.

5>关闭资源

相关代码:

import java.io.IOException;import java.net.DatagramPacket;import java.net.DatagramSocket;public class ReceiveDemo {public static void main(String[] args) throws IOException {DatagramSocket ds=new DatagramSocket(10000);byte[] bys=new byte[1024];DatagramPacket dp=new DatagramPacket(bys, 0, bys.length);ds.receive(dp);String ip = dp.getAddress().getHostAddress();byte[] data = dp.getData();int len=data.length;String string = new String(data, 0, len);System.out.println(ip+"给你发送了:"+string);ds.close();}}

TCP协议:

客户端:步骤:

1>创建客户端的Socket对象.

2>获取通道的内流(输出流)

3>使用输出流对象写数据.

4>关闭客户端socket对象资源.

相关代码:

import java.io.IOException;import java.io.OutputStream;import java.net.Socket;import java.net.UnknownHostException;public class ClientDemo {public static void main(String[] args) {try {Socket s=new Socket("10.201.18.230", 10000);OutputStream os=s.getOutputStream();os.write("TCP端来了..".getBytes());s.close();} catch (UnknownHostException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}}

服务器端:步骤:

1>创建服务器的Socket对象.

2>服务器端需要监听客户端的连接.

3>获取通道里的输入流.

4>将数据获取并显示控制台.

5>关闭服务器的Socket对象资源.

相关代码:

import java.io.IOException;import java.io.InputStream;import java.net.InetAddress;import java.net.ServerSocket;import java.net.Socket;public class ServerDemo {public static void main(String[] args) {try {ServerSocket ss=new ServerSocket(10000);System.out.println("等待客户端连接.");Socket s=ss.accept();System.out.println("客户端已经连接.");InputStream is=s.getInputStream();byte[] bys=new byte[1024];int len=is.read(bys);String str=new String(bys,0,len);InetAddress inetAddress = s.getInetAddress();String hostAddress = inetAddress.getHostAddress();System.out.println(hostAddress+"给你发送了"+str);s.close();} catch (IOException e) {e.printStackTrace();}}}

例题:客户端文本文件,服务器端将文本文件中的内容复制输出到一个新的文本文件中,并且服务器端反馈给客户端,文件复制成功了.

相关代码:

import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.FileNotFoundException;import java.io.FileReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStreamWriter;import java.net.Socket;import java.net.UnknownHostException;//客户端public class UploadClientDemo {public static void main(String[] args)  {Socket s = null;BufferedReader br = null;try {s = new Socket("10.201.18.230", 10000);br = new BufferedReader(new FileReader("ClientDemo.java"));BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));String line=null;while((line=br.readLine())!=null){bw.write(line);bw.newLine();bw.flush();}//通过这个方法告诉服务器端,客户端这边没数据了,读完反馈s.shutdownOutput();BufferedReader brClient = new BufferedReader(new InputStreamReader(s.getInputStream()));String readLine = brClient.readLine();System.out.println(readLine);} catch (UnknownHostException e) {e.printStackTrace();} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally{if(br!=null){try {br.close();} catch (IOException e) {e.printStackTrace();}}if(s!=null){try {s.close();} catch (IOException e) {e.printStackTrace();}}}}}

import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.FileWriter;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStreamWriter;import java.net.ServerSocket;import java.net.Socket;//服务器端public class UploadRerverDemo {public static void main(String[] args) {BufferedWriter bw=null;Socket s=null;try {ServerSocket ss=new ServerSocket(10000);s=ss.accept();BufferedReader br=new BufferedReader(new InputStreamReader(s.getInputStream()));bw=new BufferedWriter(new FileWriter("ServerDemo.java"));String line=null;while((line=br.readLine())!=null){bw.write(line);bw.newLine();bw.flush();}BufferedWriter bwRerver=new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));bwRerver.write("文件复制完了.");bwRerver.newLine();bwRerver.flush();} catch (IOException e) {e.printStackTrace();}finally{if(bw!=null){try {bw.close();} catch (IOException e) {e.printStackTrace();}}if(s!=null){try {s.close();} catch (IOException e) {e.printStackTrace();}}}}}