网络编程入门（代码很详细）
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网络编程
1.1概述
计算机网络：计算机网络是指将地理位置不同的具有独立功能的多台计算机及其外部设备，通过通信线路连接起来，在网络操作系统，网络管理软件及网络通信协议的管理和协调下，实现资源共享和信息传递的计算机系统。
网络编程的目的：传播交流信息、数据交换、通信。
想要达到什么效果需要什么：
如何准确定位网络上的某台主机。IP地址+端口。定位到计算机上的某个资源。找到这台主机，如何传输数据。
网络编程：TCP/IP C/S
1.2、网络通信的要素
如何实现网络的通信：
通信双方的地址：
IP
端口号
规则：网络通信的协议。
小结：
网络编程中有两个主要问题：
如何准确的定位到网络上的一台或多台主机。（ping命令）找到主机后如何进行通信。 网络编程中的要素：
IP地址和端口号网络通信协议
1.3、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域名：便于记忆IP地址
package com.zhang.lesson01;
//测试IP
import java.net.InetAddress;
import java.net.UnknownHostException;
public class TestInetAdress {
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 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);
//常用方法
System.out.println(inetAddress2.getAddress());
System.out.println(inetAddress2.getCanonicalHostName());//规范的名字
System.out.println(inetAddress2.getHostAddress());//ip
System.out.println(inetAddress2.getHostName());//域名，或者自己电脑的名字
} catch (UnknownHostException e) {
e.printStackTrace();
}
}
}
1.4、端口Port
端口表示计算机上的一个程序的进程。
不同的进程有不同的端口号，用来区分软件。端口被规定为0-65535单个协议下，端口号不能冲突
一些简单命令：
netstat -ano #查看所有端口
netstat -ano|findsr " " #查找具体端口
tasklist|findsr " "
ctrl + shift + esc #打开任务管理器
package com.zhang.lesson01;
import java.net.InetSocketAddress;
//
public class TestInetSocketAdress {
public static void main(String[] args) {
InetSocketAddress address1 = new InetSocketAddress("127.0.0.1", 8080);
System.out.println(address1);
InetSocketAddress address2 = new InetSocketAddress("localhost", 8080);
System.out.println(address2);
System.out.println(address1.getAddress());
System.out.println(address1.getHostName());
System.out.println(address1.getPort());
}
}
1.5、通信协议
协议：就是约定。
**网络通信协议：**速率、传输速率、代码结构、传输控制~
TCP/IP协议簇
重要：
TCP：用户传输协议UDP：用户数据报协议IP：网络互连协议
1.6、TCP
1.6.1 TCP实现聊天
客户端
连接服务器Socket发送消息
package com.zhang.lesson02;
import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
//客户端
public class TcpClientDemo01 {
public static void main(String[] args) {
//1.需要一个地址
Socket socket=null;
OutputStream outputStream=null;
try {
InetAddress serverip = InetAddress.getByName("127.0.0.1");
//2.端口号
int port=9999;
//3.创建一个socket连接
socket = new Socket(serverip,port);
//4.发送消息
outputStream = socket.getOutputStream();
outputStream.write("你好，欢迎学习Java".getBytes());
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}finally {
if(outputStream!=null){
try {
outputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(socket!=null){
try {
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
服务器
建立服务器端口ServerSocket等待用户连接accept接收用户消息
package com.zhang.lesson02;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;
//服务器端
public class TcpServerDemo01 {
public static void main(String[] args) {
//1.我得有个地址
ServerSocket serverSocket=null;
Socket socket=null;
InputStream inputStream=null;
ByteArrayOutputStream byteArrayOutputStream=null;
try {
serverSocket = new ServerSocket(9999);
//2.等待客户端连接
while (true) {
socket = serverSocket.accept();
//3.读取客户端的消息
inputStream = socket.getInputStream();
//管道流
byteArrayOutputStream = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int length;
while ((length = inputStream.read(buffer)) != -1) {
byteArrayOutputStream.write(buffer, 0, length);
}
System.out.println(byteArrayOutputStream.toString());
}
} catch (IOException e) {
e.printStackTrace();
}finally {
//关闭资源
if(byteArrayOutputStream!=null){
try {
byteArrayOutputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (inputStream!=null){
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(socket!=null){
try {
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(serverSocket!=null){
try {
serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
1.6.2 TCP实现文件上传
客户端：
package com.zhang.lesson02;
import java.io.*;
import java.net.InetAddress;
import java.net.Socket;
public class TcpClientDemo02 {
public static void main(String[] args) throws Exception {
//创建socket连接
Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9090);
//2.创建一个输出流
OutputStream os = socket.getOutputStream();
//3.文件流
FileInputStream fis = new FileInputStream("bizhi.jpg");
//4.写出文件
byte[] buffer = new byte[1024];
int len;
while((len=fis.read(buffer))!=-1){
os.write(buffer,0,len);
}
//通知服务器结束
socket.shutdownOutput();//传输完毕
//确定接收完毕
InputStream inputStream = socket.getInputStream();
//String byte[]
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer2 = new byte[1024];
int len2;
while((len2=inputStream.read(buffer2))!=-1){
baos.write(buffer2,0,len2);
}
System.out.println(baos.toString());
//5.关闭资源
baos.close();
inputStream.close();
fis.close();
socket.close();
}
}
服务器：
package com.zhang.lesson02;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
public class TcpServerDemo02 {
public static void main(String[] args) throws Exception {
//1.创建服务
ServerSocket serverSocket = new ServerSocket(9090);
//2.监听客户端的连接
Socket socket = serverSocket.accept();//阻塞式监听，一直等待客户端连接
//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);
}
//通知客户端接收完毕
OutputStream os = socket.getOutputStream();
os.write("我接受完毕，你可以断开l".getBytes());
//关闭资源
fos.close();
is.close();
socket.close();
serverSocket.close();
}
}
1.7、UDP
1.7.1 UDP发送消息
发送端：
package com.zhang.lesson03;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
public class TestUdpClient {
public static void main(String[] args) throws Exception {
//不需要连接服务器
//1.建立一个socket
DatagramSocket socket = new DatagramSocket();
//2.建个包
String msg="你好啊，我是胡歌";
//发送给谁
InetAddress localhost = InetAddress.getByName("localhost");
int port=9000;
//数据，数据的长度起始，要发送给谁
DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);
//3.发送包
socket.send(packet);
//4.关闭流
socket.close();
}
}
接收方：
package com.zhang.lesson03;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class TestUdpServer {
public static void main(String[] args) throws Exception{
//1.开放端口
DatagramSocket socket = new DatagramSocket(9000);
//2.接收数据包
byte[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);
socket.receive(packet);
//System.out.println(packet.getData().toString());
System.out.println(packet.getAddress());
System.out.println(new String(packet.getData(),0,packet.getLength()));
//3.关闭连接
socket.close();
}
}
1.7.2 UDP实现聊天
发送方：
package com.zhang.chart;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
public class UdpSenderDemo01 {
public static void main(String[] args) throws Exception{
DatagramSocket socket = new DatagramSocket(8888);
//准备数据 控制台读取
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
while (true){
String data = reader.readLine();
DatagramPacket packet = new DatagramPacket(data.getBytes(),0,data.getBytes().length,new InetSocketAddress("localhost",8000));
socket.send(packet);
if (data.equals("bye")){
break;
}
}
socket.close();
}
}
接收方：
package com.zhang.chart;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class UdpReceiveDemo01 {
public static void main(String[] args) throws Exception {
DatagramSocket socket = new DatagramSocket(8000);
while (true){
//准备接收包裹
byte[] container = new byte[1024];
DatagramPacket packet = new DatagramPacket(container,0,container.length);
socket.receive(packet);//阻塞式接收包裹
//断开连接
byte[] data=packet.getData();
String rdata = new String(data, 0, packet.getLength());
System.out.println(rdata);
if (rdata.equals("bye")){
break;
}
}
socket.close();
}
}
1.7.3 UDP实现多线程聊天
首先分别写出信息发送类，以及信息接收类。
信息发送类：
package com.zhang.chart;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketException;
public class TalkSender implements Runnable {
DatagramSocket socket = null;
BufferedReader reader = null;
private String toIP;
private int toPort;
private int fromPort;
public TalkSender(String toIP, int toPort, int fromPort) {
this.toIP = toIP;
this.toPort = toPort;
this.fromPort = fromPort;
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();
DatagramPacket packet = new DatagramPacket(data.getBytes(), 0, data.getBytes().length, new InetSocketAddress(this.toIP,this.toPort));
socket.send(packet);
if (data.startsWith("bye")) {
break;
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
信息接收类：
package com.zhang.chart;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
public class TalkReceiver implements Runnable{
DatagramSocket socket=null;
private int Port;
private String msgFrom;
public TalkReceiver(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 {
//准备接收包裹
byte[] container = new byte[1024];
DatagramPacket packet = new DatagramPacket(container,0,container.length);
socket.receive(packet);//阻塞式接收包裹
//断开连接
byte[] data=packet.getData();
String rdata = new String(data, 0, packet.getLength());
System.out.println(msgFrom+":"+rdata);
if (rdata.equals("bye")){
break;
}
} catch (IOException e) {
e.printStackTrace();
}
}
socket.close();
}
}
两个具有多线程的启动类：
package com.zhang.chart;
public class TalkStudent {
public static void main(String[] args) {
//开启两个线程
new Thread(new TalkSender("localhost",9999,7777)).start();
new Thread(new TalkReceiver(8888,"老师")).start();
}
}
package com.zhang.chart;
public class TalkTeacher {
public static void main(String[] args) {
new Thread(new TalkSender("localhost",8888,5555)).start();
new Thread(new TalkReceiver(9999,"学生")).start();
}
}
1.8、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：默认端口/项目名/资源
初识URL类。
package com.zhang.lesson04;
import java.net.MalformedURLException;
import java.net.URL;
public class URLDemo01 {
public static void main(String[] args) throws MalformedURLException {
URL url = new URL("http://localhost:80/helloworld/index");
System.out.println(url.getPath());//文件
System.out.println(url.getProtocol());//协议
System.out.println(url.getHost());//IP
//.....
}
}
URL下载文档。这里我在网页版网易云下载到了一首歌曲《New Boy》，有兴趣可以自己操作哦。
package com.zhang.lesson04;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
public class UrlDown {
public static void main(String[] args) throws Exception{
//1.下载地址
URL url = new URL("https://m801.music.126.net/20210803202948/9a3ef3141be50e1a5974151a7649e1f1/jdyyaac/obj/w5rDlsOJwrLDjj7CmsOj/9840227679/a5cf/2261/7132/e26562647c7ce931b0cc7545ff1883b5.m4a");
//2.连接到这个资源
HttpURLConnection urlConnection=(HttpURLConnection)url.openConnection();
InputStream inputStream = urlConnection.getInputStream();
FileOutputStream fos = new FileOutputStream("file01.m4a");
byte[] buffer = new byte[1024];
int len;
while((len=inputStream.read())!=-1){
fos.write(buffer,0,len);
}
fos.close();
inputStream.close();
urlConnection.disconnect();
}
希望对大家有帮助~