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地球村:你在一个地方,但是在另外一个地方
计算机网络
计算机网络是指将 地理位置不同的具有的独立功能的多台计算机以及其外部设备,通过通信线路连接起来,在因特网操作系统,网络管理软件以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系统
网络编程的目的
想要达到这个效果需要什么?
JavaWeb开发:网页编程 B/S
网络编程 TCP/IP:C/S
人工智能:智能化汽车
如何实现网络的通信:
ip地址
ip地址:InetAddress
唯一定位一台网络上的计算机
127.0.0.1:本机地址 等价于 localhost
ip地址的分类
域名:记忆IP问题
public class TestInetAddress {
public static void main(String[] args) {
try {
// 查询网络地址
InetAddress byName = InetAddress.getByName("www.baidu.com");
InetAddress localHost = InetAddress.getLocalHost();
System.out.println(localHost);
System.out.println(byName);
// 常用的方法
System.out.println(byName.getHostName());
System.out.println(byName.getAddress());
// 规范的名字
System.out.println(byName.getCanonicalHostName());
System.out.println(byName.getHostAddress());
} catch (UnknownHostException e) {
e.printStackTrace();
}
}
}
端口
端口表示计算机上的一个程序的进程
不同的进程有不同的端口号!用来区分软件!
被规定到 0~65535
TCP和UDP:加在一起就是 65535 * 2,单个写一下端口号不能冲突
端口分类
共有端口 0~1023
程序注册端口:1024~49151
动态端口、私有端口:49152~65535
netstat -ano # 查看所有的端口
netstat -ano |findstr "5900" # 查询某个端口
tasklist|findstr "5464" # 查看指定端口的进程
public class TestInetSocketAddress {
public static void main(String[] args) {
InetSocketAddress inetSocketAddress = new InetSocketAddress("127.0.0.1", 8080);
System.out.println(inetSocketAddress);
System.out.println(inetSocketAddress.getAddress());
System.out.println(inetSocketAddress.getHostName());
}
}
通信协议
协议:约定,就是现在说的普通话
网络通信协议:速率,传输码率,代码结构,传输控制
大事化小:分层
TCP/IP 协议簇,实际上是一组协议
出名协议:
TCP和UDP对比
TCP:打电话
连接、稳定
三次握手 四次挥手
最少三次才能保证连接
A:你瞅啥?
B:瞅你咋地?
A:来,干你
A:我要断开了
B:我知道你要断开了
B:你真的断开了?
A:我真的断开了
客户端、服务端
传输完成,就会释放连接
UDP:发短信
TCP协议
客户端
服务器
public class TcpClientDemo01 {
public static void main(String[] args) {
Socket socket = null;
OutputStream os = null;
try {
//1. 要知道服务器的地址
InetAddress serverIp = InetAddress.getByName("127.0.0.1");
//2. 端口号
int port = 10000;
//3. 创建一个Socket连接
socket = new Socket(serverIp, port);
//4. 发送消息
os = socket.getOutputStream();
os.write("hello,小猪童鞋".getBytes());
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
socket.close();
os.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
public class TcpServerDemo01 {
public static void main(String[] args) {
ServerSocket serverSocket = null;
Socket socket = null;
InputStream is = null;
ByteArrayOutputStream baos = null;
try {
//1.我需要有一个地址
serverSocket = new ServerSocket(10000);
while (true) {
//2. 等待客户端连接过来
socket = serverSocket.accept();
//3.读取客户端的消息
is = socket.getInputStream();
baos = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len;
while ((len = is.read(buffer)) != -1) {
baos.write(buffer, 0, len);
}
System.out.println(baos.toString());
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
baos.close();
is.close();
socket.close();
serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
服务器端
public class TcpServerDemo02 {
public static void main(String[] args) throws Exception {
//1.创建服务
ServerSocket serverSocket = new ServerSocket(10000);
//2.监听客户端的连接
// 阻塞式监听,会一直监听客户端的请求连接
Socket socket = serverSocket.accept();
//3.获取输入流
InputStream is = socket.getInputStream();
//4.文件输出
FileOutputStream fos = new FileOutputStream(new File("res.doc"));
byte[] buffer = new byte[1024];
int len;
while ((len = is.read(buffer)) != -1) {
fos.write(buffer, 0, len);
}
// 通知服务端接收完毕
OutputStream os = socket.getOutputStream();
os.write("我接收完毕了,你可以断开了".getBytes());
//5.关闭资源
fos.close();
is.close();
socket.close();
serverSocket.close();
}
}
客户端
public class TcpClientDemo02 {
public static void main(String[] args) throws Exception {
//1. 创建一个Socket连接
Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 10000);
//2. 创建一个输出流
OutputStream os = socket.getOutputStream();
//3. 文件流 读取文件
FileInputStream fis = new FileInputStream(new File("ic.doc"));
//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,我已经接收完毕
// 我已经传输完了
socket.shutdownOutput();
// 确定服务端接收完毕,才能断开连接
InputStream inputStream = socket.getInputStream();
// String 类型的数组
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] bytes = new byte[1024];
int len2;
while ((len2 = inputStream.read(bytes)) != -1) {
baos.write(bytes, 0, len2);
}
System.out.println(baos.toString());
//5. 关闭资源
baos.close();
inputStream.close();
fis.close();
os.close();
socket.close();
}
}
服务端
客户端
发短信:不用连接,需要知道对方的地址
发送消息
public class UdpClientDemo01 {
public static void main(String[] args) throws Exception {
//1. 建立一个Socket
DatagramSocket socket = new DatagramSocket();
//2. 建个包
String message = "你好,服务器";
// 发送给谁
InetAddress localhost = InetAddress.getByName("localhost");
int port = 10000;
// 数据 数据的开始位置 数据的长度 主机地址 主机端口号地址
DatagramPacket datagramPacket = new DatagramPacket(
message.getBytes(),
0,
message.getBytes().length,
localhost,
port
);
//3. 发送包
socket.send(datagramPacket);
//4. 关闭
socket.close();
}
}
接收消息
public class UdpServerDemo02 {
public static void main(String[] args) throws Exception {
//1. 开放端口
DatagramSocket socket = new DatagramSocket(10000);
//2. 接收数据包
byte[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);
// 阻塞接收
socket.receive(packet);
System.out.println( new String(packet.getData(), 0, packet.getLength()));
//3. 关闭连接
socket.close();
}
}
如咨询的场景
public class UdpSenderDemo01 {
public static void main(String[] args) throws Exception {
DatagramSocket socket = new DatagramSocket(10000);
// 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 ("bye".equals(data)) {
break;
}
}
socket.close();
}
}
public class UdpReceiveDemo01 {
public static void main(String[] args) throws Exception {
DatagramSocket socket = new DatagramSocket(6666);
while (true) {
// 准备接收包裹
byte[] container = new byte[1024];
DatagramPacket packet = new DatagramPacket(container, 0, container.length);
// 阻塞式接收
socket.receive(packet);
// 断开连接
byte[] data = packet.getData();
String receiveData = new String(data, 0, data.length);
System.out.println(receiveData);
if ("bye".equals(receiveData)) {
break;
}
}
socket.close();
}
}
在线咨询:两个人都可以是发送方,也都可以是接收方
发送方
public class TalkSend implements Runnable {
DatagramSocket socket = null;
BufferedReader reader = null;
private int fromIp;
private String toIp;
private int toPort;
public TalkSend(int fromIp, String toIp, int toPort) throws Exception {
this.fromIp = fromIp;
this.toIp = toIp;
this.toPort = toPort;
this.socket = new DatagramSocket(fromIp);
this.reader = new BufferedReader(new InputStreamReader(System.in));
}
@Override
public void run() {
try {
// 准备数据:控制台读取 System.in
while (true) {
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 ("bye".equals(data)) {
break;
}
}
} catch (Exception e) {
e.printStackTrace();
}
socket.close();
}
}
接收方
public class TalkReceive implements Runnable {
DatagramSocket socket = null;
private int port;
private String msgFrom;
public TalkReceive(int port, String msgFrom) throws Exception {
this.port = port;
this.msgFrom = msgFrom;
socket = new DatagramSocket(this.port);
}
@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);
// 阻塞式接收
socket.receive(packet);
// 断开连接
byte[] data = packet.getData();
String receiveData = new String(data, 0, data.length);
System.out.println(msgFrom + ":" + receiveData);
if ("bye".equals(receiveData)) {
break;
}
} catch (Exception e) {
e.printStackTrace();
}
}
socket.close();
}
}
测试:学生线程
public class TalkStudent {
public static void main(String[] args) throws Exception {
// 开启两个线程
new Thread(new TalkSend(7777, "localhost", 10000)).start();
new Thread(new TalkReceive(8888, "老师")).start();
}
}
测试:老师线程
public class TalkTeacher {
public static void main(String[] args) throws Exception {
new Thread(new TalkSend(5555, "localhost", 8888)).start();
new Thread(new TalkReceive(10000, "学生")).start();
}
}
统一资源定位符:定位资源的,互联网上的资源
DNS域名解析
协议://ip地址:端口/项目名/资源
public class UrlDemo02 {
public static void main(String[] args) throws Exception {
//下载地址
URL url = new URL("https://m701.music.126.net/20200724114352/48a179e4bbf0205c0a711aa07bd689b1/jdyyaac/5409/060b/5253/ccf875c05f1a97a210f7e926d421c52d.m4a");
//连接下载资源
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
InputStream inputStream = conn.getInputStream();
FileOutputStream fos = new FileOutputStream("有何不可.m4a");
byte[] bytes = new byte[1024];
int len;
while ((len = inputStream.read(bytes)) != -1) {
//读取数据
fos.write(bytes, 0, len);
}
fos.close();
inputStream.close();
conn.disconnect();
}
}
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