网络编程

文章目录

网络编程TCP协议UDP协议socket(套接字)TCP案例模板：1.客户端建立链接、服务端准备服务（ip（可省略）、端口）2.通过socket生成InputStream/OutputStream（准备发送数据）3.使用InputStream/OutputStream进行发送、接收数据4.关闭InputStream/OutputStream、socket对象流处理多用户问题UDP案例模板网络编程中一些工具类InetAddress**URL /URLConnection**

ip地址：网络上的唯一标识

ip的组成：32位组成，由4个8位二进制（每一位最大值是255，每一位十进制标识0-255）

协议：为了让网络中不同计算机之间能够相互通信而简历的规则、标准、约定

TCP协议

面向连接、可靠的（不丢失、不重复、有序）、基于字节流的传输通信协议。(传输速度相对慢)

UDP协议

无连接的协议。在传输数据之前。客户端和服务器之间不建立和维护链接。提供不可靠的数据传输（速度快）

socket(套接字)

基于TCP协议的网络通信，可以提供双向安全的网络通信。

socket需要借助于数据流（字节流）来完成数据的传递工作：重点

发送数据：OutputStream接收数据：InputStream

TCP案例模板：

1.客户端建立链接、服务端准备服务（ip（可省略）、端口）

本机默认ip：127.0.0.1/localhost

2.通过socket生成InputStream/OutputStream（准备发送数据）

3.使用InputStream/OutputStream进行发送、接收数据

4.关闭InputStream/OutputStream、socket

服务端(ServerSocket)

package demo01;import java.io.*;import .ServerSocket;import .Socket;public class MyServer {public static void main(String[] args) {// 1.准备服务.ip:默认本机127.0.0.1,端口8888ServerSocket serverSocket = null ;Socket socket = null ;InputStream in = null ;BufferedReader reader = null ;OutputStream out = null ;try {serverSocket = new ServerSocket(8888) ;System.out.println("服务器启动");//准备完毕，可以监听客户端请求socket = serverSocket.accept();//一直阻塞，直到有客户端连接System.out.println("服务端检测到客户端连接成功！");// 2.通过socket生成inputstream/outputstream（准备发送数据）//3.使用inputstream/outputstream进行发送、接受数据in = socket.getInputStream();//带缓冲区的字符流（字节流-转换流-字符流）reader = new BufferedReader(new InputStreamReader(in));String info = null ;while( (info=reader.readLine()) != null ){System.out.println("I am server,接受到客户端信息是：" + info); socket.shutdownInput();//服务端做出反馈out = socket.getOutputStream();out.write("welcome client....".getBytes());socket.shutdownOutput();} catch (IOException e) {e.printStackTrace();}finally{try {// 4.关闭inputstream/outputstream、socketif(reader !=null) reader.close();if(out !=null) out.close();if(in !=null) in.close();if(socket !=null) socket.close();if(serverSocket !=null) serverSocket.close();} catch (IOException e) {e.printStackTrace();}}}}

客户端(Socket)

package demo01;import java.io.*;import .Socket;/** Created by 颜群*/public class MyClient {public static void main(String[] args) {Socket socket = null ;OutputStream out = null ;InputStream in = null ;BufferedReader reader = null ;try {socket = new Socket("127.0.0.1",8888);System.out.println("客户端链接成功！");out = socket.getOutputStream();out.write( "hello server".getBytes() );socket.shutdownOutput();//接收服务端的反馈in = socket.getInputStream();reader = new BufferedReader(new InputStreamReader(in));String info = null;while( (info=reader.readLine()) != null ){System.out.println("I am client,接收到的服务端消息："+info);}socket.shutdownInput();} catch (IOException e) {e.printStackTrace();}finally{try {if(out!=null) out.close();if(in!=null) in.close();if(socket!=null) socket.close();} catch (IOException e) {e.printStackTrace();}}}}

对象流

网络传递一个对象：

1.将要传递的对象序列化 (对象implements Serializable)

2.使用对象流（ObjectInputSream\ObiectOutputStream）

要传递的对象

package Demo02;import java.io.Serializable;public class Student implements Serializable {private int sid;private String name;private int age;public Student() {}public Student(int sid, String name, int age) {this.sid = sid;this.name = name;this.age = age;}public int getSid() {return sid;}public void setSid(int sid) {this.sid = sid;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}@Overridepublic String toString() {return "Student{" +"sid=" + sid +", name='" + name + '\'' +", age=" + age +'}';}}

服务端

package Demo02;import java.io.*;import .ServerSocket;import .Socket;public class MyServer {public static void main(String[] args) {ServerSocket serverSocket = null;Socket socket = null;InputStream in = null;ObjectInputStream ois = null;try {serverSocket = new ServerSocket(8888);socket = serverSocket.accept();//收客户端发来的对象in = socket.getInputStream();//包装ois = new ObjectInputStream(in);try {Student student = (Student) ois.readObject();System.out.println(student);socket.shutdownInput();} catch (ClassNotFoundException e) {e.printStackTrace();}} catch (IOException e) {e.printStackTrace();} finally {try {if (ois != null) ois.close();if (in != null) in.close();if (socket != null) socket.close();if (serverSocket != null) serverSocket.close();} catch (IOException e) {e.printStackTrace();}}}}

客户端

package Demo02;import java.io.IOException;import java.io.ObjectOutputStream;import java.io.OutputStream;import .Socket;public class MyClient {public static void main(String[] args) {Socket socket = null;OutputStream out = null;ObjectOutputStream oos = null;try {socket = new Socket("localhost", 8888);Student student = new Student(1001, "zs", 23);out = socket.getOutputStream();//将输出流编程对象流.装饰模式oos = new ObjectOutputStream(out);oos.writeObject(student);socket.shutdownOutput();} catch (IOException e) {e.printStackTrace();} finally {try {if (oos != null) oos.close();if (out != null) out.close();if (socket != null) socket.close();} catch (IOException e) {e.printStackTrace();}}}}

处理多用户问题

思路：

客户端：代码不变

服务端：每当有一个客户端，就开启一个新线程去处理（每个线程专门处理一个客户端对象）

要传递的对象

package Demo03;import java.io.Serializable;public class Student implements Serializable {private int sid;private String name;private int age;public Student() {}public Student(int sid, String name, int age) {this.sid = sid;this.name = name;this.age = age;}public int getSid() {return sid;}public void setSid(int sid) {this.sid = sid;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}@Overridepublic String toString() {return "Student{" +"sid=" + sid +", name='" + name + '\'' +", age=" + age +'}';}}

服务端

package Demo03;import java.io.IOException;import java.io.InputStream;import .ServerSocket;import .Socket;public class Myserver {public static void main(String[] args) {try {ServerSocket serverSocket = new ServerSocket(8888);while(true) {Socket socket = serverSocket.accept();ServerThread serverThread = new ServerThread(socket);serverThread.start();}} catch (IOException e) {e.printStackTrace();}}}

服务端线程

package Demo03;import java.io.IOException;import java.io.InputStream;import java.io.ObjectInputStream;import java.io.OutputStream;import .Socket;public class ServerThread extends Thread{Socket socket ;public ServerThread(Socket socket){this.socket = socket;}@Overridepublic void run() {InputStream in =null;ObjectInputStream ois = null;OutputStream out =null;//接收客户端数据try {in = socket.getInputStream();//装饰模式ois = new ObjectInputStream(in);Object student = (Student)ois.readObject();System.out.println(student);socket.shutdownInput();//返回文字out = socket.getOutputStream();out.write("已经收到".getBytes());} catch (IOException | ClassNotFoundException e) {e.printStackTrace();}finally {try {out.close();ois.close();in.close();socket.close();} catch (IOException e) {e.printStackTrace();}}}}

客户端

package Demo03;import java.io.IOException;import java.io.InputStream;import java.io.ObjectOutputStream;import java.io.OutputStream;import .Socket;public class MyClient {public static void main(String[] args) {Socket socket = null;OutputStream out = null;ObjectOutputStream oos = null;try {socket = new Socket("localhost", 8888);Student student = new Student(1001, "zs", 23);out = socket.getOutputStream();//将输出流编程对象流.装饰模式oos = new ObjectOutputStream(out);oos.writeObject(student);socket.shutdownOutput();InputStream in = socket.getInputStream();byte[] buf = new byte[100];in.read(buf);System.out.println("接收到服务端返葵"+new String(buf));} catch (IOException e) {e.printStackTrace();} finally {try {if (oos != null) oos.close();if (out != null) out.close();if (socket != null) socket.close();} catch (IOException e) {e.printStackTrace();}}}}

UDP案例模板

DatagramPacket（数据）：封装了数据报、数据长度、目标地址和目标端口

DatagramSocket（收发器）：接收和DatapramPacket中封装好的数据

发送

package Demo04;import java.io.IOException;import .*;/** Created by 颜群*/public class Send {public static void main(String[] args) {DatagramSocket ds = null ;//创建一个InetAddress对象InetAddress ip = null ;try {ip = InetAddress.getByName("127.0.0.1");String msg = "helloserver.." ;DatagramPacket dp = new DatagramPacket(msg.getBytes(),msg.length(),ip,9999) ;ds = new DatagramSocket() ;ds.send( dp );} catch (UnknownHostException e) {e.printStackTrace();} catch (SocketException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally{ds.close();}}}

接收

package Demo04;import java.io.IOException;import .DatagramPacket;import .DatagramSocket;import .SocketException;public class Receive {public static void main(String[] args) {byte[] data = new byte[64];//准备接受数据的对象DatagramPacket dp = new DatagramPacket(data, data.length);DatagramSocket ds =null;//接收数据try {ds = new DatagramSocket(9999);ds.receive(dp);//显示接收数据String s = new String(dp.getData(),0, data.length);System.out.println("接收到的数据"+s);System.out.println("显示发送方的信息"+dp.getAddress().getHostAddress());} catch (SocketException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally {ds.close();}}}

总结：发送数据使用的工具

tcp：字节流

udp:DatagramScoket

网络编程中一些工具类

InetAddress

public static void main(String[] args) {InetAddress host = null;try {//本机host = InetAddress.getLocalHost();System.out.println(host);//网络中任意一台InetAddress host163 = InetAddress.getByName("");System.out.println(host163);} catch (UnknownHostException e) {e.printStackTrace();}}

URL /URLConnection

以下示例，注意点：输入流 url-内存； 输出流：内存-本地

package demo05;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import .MalformedURLException;import .URL;import .URLConnection;/** Created by 颜群*/public class URLDemo {public static void main(String[] args) {InputStream in = null ;URLConnection urlConnection = null;OutputStream out = null ;try {URL url = new URL("/") ;urlConnection = url.openConnection();in = urlConnection.getInputStream();out = new FileOutputStream("d:\\163.txt");byte[] buf = new byte[64] ;int len = -1 ;while( (len = in.read(buf)) != -1 ){out.write(buf,0,len);}} catch (MalformedURLException e) {e.printStackTrace();}catch (IOException e) {e.printStackTrace();}finally{try {if(out!=null) out.close();if(in!=null) in.close();} catch (IOException e) {e.printStackTrace();}}}}

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