1.1网络通信的要素
通信双方地址：
-
ip
-
端口号
规则：网络通信协议
TCP/IP参考模型：
1.2 IP
ip地址：InetAddress
-
唯一定位一台网络上的计算机
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127.0.0.1 ：本机（localhost）
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ip地址的分类
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ipv4/ipv6
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ipv4 127.0.0.1，4个字节组成，范围 0~255
-
ipv6 128位，8个无符号整数
-
-
公网（互联网）、私网（局域网）分类
-
ABCD类地址
-
192.168.xx.xx，专门给组织内部使用的
-
-
-
域名：记忆IP问题
//测试IP
public class TestInetAddress {
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);
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();
}
}
}
1.3 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0~65535
-
TCP、UDP：65535*2 TCP用了80端口，UDP也可以用80端口，这两个协议不冲突。单个协议下，端口号不能冲突。
-
端口分类
-
公有端口 0~1023
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HTTP: 80
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HTTPS: 443
-
FTP: 21
-
Telnet: 23
-
-
程序注册端口：1024~49151，分配用户或者程序
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Tomcat: 8080
-
MySQL: 3306
-
Oracle: 1521
-
-
动态、私有：49152~65535
netstat -ano #查看所有的端口
netstat -ano|findstr "5900" #查看指定的端口
tasklist|findstr "8696" #查看指定端口的进程
Ctrl+shift+ESC #打开任务管理器
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1.4通信协议
TCP/IP（网络互连协议）协议簇：实际上是一组协议
重要：
-
TCP：用户传输协议
-
UDP：用户数据报协议
TCP UDP 对比
TCP：打电话
-
连接，稳定
-
三次握手 四次挥手
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客户端、服务端
-
传输完成，释放连接，效率低
UDP：发短信
-
不连接，不稳定
-
客户端、服务端：没有明确的界限
-
不管有没有准备好，都可以发送
-
DDOS：分布式拒绝服务攻击（洪水攻击）
1.5 TCP实现聊天
客户端
-
连接服务器 Socket
-
发送消息
package com.kuang.leson02;
import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import java.nio.charset.StandardCharsets;
// 客户端
public class TcpClientDemo01 {
public static void main(String[] args) {
Socket socket = null;
OutputStream os = null;
try {
//1. 客户端连接服务器要知道服务器的地址、端口号
InetAddress serverIP = InetAddress.getByName("127.0.0.1");
int port = 9999;
//2. 创建一个Socket连接
socket =new Socket(serverIP,port);
//3. 发送消息 IO流
os = socket.getOutputStream();
os.write("万事顺意，平安喜乐".getBytes());
} catch (Exception e) {
e.printStackTrace();
}finally{
if(os!=null){
try {
os.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(socket!=null){
try {
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
服务器
-
建立服务的端口 ServerSocket
-
等待用户连接 accept
-
接收用的消息
package com.kuang.leson02;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;
// 服务端
public class TcpServerDemo01 {
public static void main(String[] args) {
ServerSocket serverSocket = null;
Socket socket = null;
InputStream is = null;
ByteArrayOutputStream baos = null;
try {
//1. 服务器得有一个地址
serverSocket = new ServerSocket(9999);
// 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();
// 4.管道流
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 {
//关闭资源
if(baos!=null){
try {
baos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(is!=null){
try {
is.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 TCP文件上传实现
客户端读取文件，服务端接收文件
package com.kuang.leson02;
import java.io.*;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
//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"),9000);
//2. 创建一个输出流
OutputStream os = socket.getOutputStream();
//3. 文件流
FileInputStream fis = new FileInputStream(new File("BasicGrammar/lib/a.jpg"));
//4. 写出文件
byte[] buffer = new byte[1024];
int len;
while((len = fis.read(buffer))!=-1){
os.write(buffer,0,len);
}
//通知服务器已经结束
socket.shutdownOutput();
//确定服务器接收完毕，才能够断开连接
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());
// 关闭资源
baos.close();
inputStream.close();
fis.close();
os.close();
socket.close();
}
}
package com.kuang.leson02;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
//服务器端
public class TcpServerDemo02 {
public static void main(String[] args) throws Exception {
//1. 创建服务
ServerSocket serverSocket = new ServerSocket(9000);
//2. 监听客户端的连接
Socket socket = serverSocket.accept();//阻塞时监听，会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("BasicGrammar/lib/d.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("接收完毕".getBytes());
// 关闭资源
fos.close();
is.close();
socket.close();
serverSocket.close();
}
}
Tomcat
1.7 UDP
发短信：不用连接，但需要知道对方的地址
发送端
package com.kuang.lesson03;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
//不需要连接服务器
public class UdpDemo01 {
public static void main(String[] args) throws Exception {
//1. 建立一个Socket
DatagramSocket socket = new DatagramSocket();
//2. 建个包
String msg = "上海疫情早日清零";
//发送给谁
InetAddress localhost = InetAddress.getByName("localhost");
int port = 9090;
// 数据，数据的长度，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();
}
}
接收端
package com.kuang.lesson03;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
public class UdoDemo02 {
public static void main(String[] args) throws Exception {
// 开放端口
DatagramSocket socket = new DatagramSocket(9090);
// 接收数据包
byte[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);
socket.receive(packet);//阻塞接收
System.out.println(packet.getAddress().getHostName());
System.out.println(new String(packet.getData(),0,packet.getLength()));
//关闭连接
socket.close();
}
}
单向聊天
循环发送消息
package com.kuang.chat;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketException;
import java.nio.charset.StandardCharsets;
public class UdpSenderDemo01 {
public static void main(String[] args) throws Exception {
DatagramSocket socket = new DatagramSocket(8888);
while(true){
//准备数据：控制台读取 System.in
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String data = reader.readLine();
byte[] datas = data.getBytes();
DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress("localhost",6666));
socket.send(packet);
if(data.equals("byebye")){
break;
}
}
socket.close();
}
}
循环接收消息
package com.kuang.chat;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
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);
socket.receive(packet);//阻塞式接收包裹
//断开连接
byte[] data = packet.getData();
String receiveData = new String(data,0, data.length);
System.out.println(receiveData);
if(receiveData.equals("byebye")){
break;
}
}
socket.close();
}
}
在线咨询：双方都可以是发送方，也都可以是接收方
发送线程
package com.kuang.chat;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketException;
public class talkSend implements Runnable{
DatagramSocket socket = null;
BufferedReader reader = null;
private int fromPort;
private String toIp;
private int toPort;
public talkSend(int fromPort,String toIp,int toPort){
this.fromPort= fromPort;
this.toIp = toIp;
this.toPort = toPort;
try {
socket = new DatagramSocket(8888);
reader = new BufferedReader(new InputStreamReader(System.in));
} catch (Exception e) {
e.printStackTrace();
}
}
接收线程
package com.kuang.chat;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
public class talkReceive implements Runnable{
DatagramSocket socket = null;
private int port;
private String msgFrom;
public talkReceive(int port,String msgFrom){
this.port = port;
this.msgFrom = msgFrom;
try {
socket = new DatagramSocket(port);
} catch (SocketException e) {
e.printStackTrace();
}
}
二者对话
package com.kuang.chat;
public class teacherTalk {
public static void main(String[] args) {
new Thread(new talkSend(5554,"localhost",6060)).start();
new Thread(new talkReceive(9999,"学生")).start();
}
}
package com.kuang.chat;
public class studentTalk {
public static void main(String[] args) {
new Thread(new talkSend(7777,"localhost",9999)).start();
new Thread(new talkReceive(6060,"老师")).start();
}
}
1.8 URL(统一资源定位符)
