网络编程
网络编程
网络编程的目的:数据交换,通信
网络通信的要素
1.通信双方的地址
ip
端口号
192.168.16.124:5900
2.规则:网络通信的协议
OSI 7层协议模型与TCP/IP 4层协议模型
OSI 7层协议模型
TCP/IP 4层协议模型
小结:
1.网络编程中有两个主要的问题
- 如何准确的定位到网络上的一台或多台主机
- 找到主机之后如何进行通信
2.网络编程中的要素
- IP和端口号 IP类
- 网络通信协议 udp,tcp类
3.Java是面向对象编程,万物皆可对象
ip
ip地址:InetAddress类
-
唯一定义一台网络上的计算机
-
127.0.0.1:本机 localhost
-
ip地址的分类
-
公网(互联网)--私网(局域网)
- ABCD类地址
- 192.168.xx.xx,专门给组织内部使用(局域网)
-
ipv4/ipv6
- ipv4 像127.0.0.1这样的,4个字节组成,每个字节的范围0~255,有42亿个ipv4地址;30亿在北美,亚洲4亿,2011年就用尽了
- ipv6 :128位,8个无符号整数形如: fe80::cddd:c6b0:d9a6:e5e8%14 或 2000:0c4d:dcsx:sdsa:hcdd:anan:sdkd:sjak 很多了,无穷多
-
-
域名:记忆IP问题
- IP 对应着 www.baidu.com
package mynet;
import java.net.InetAddress;
import java.net.UnknownHostException;
public class TestInetAdress01 {
public static void main(String[] args) {
try {
//获取网络ip
InetAddress inetAddress1 = InetAddress.getByName("java.sun.com");
System.out.println(inetAddress1);
InetAddress inetAddress2 = InetAddress.getByName("www.baidu.com");
System.out.println(inetAddress2);
//获取本地ip
InetAddress inetAddress3 = InetAddress.getByName("127.0.0.1");
System.out.println(inetAddress3);
InetAddress inetAddress4 = InetAddress.getByName("localhost");
System.out.println(inetAddress4);
InetAddress localHost = InetAddress.getLocalHost();
System.out.println(localHost);
System.out.println("===========");
//常用方法
System.out.println(inetAddress2.getAddress());//获取地址
System.out.println(inetAddress2.getCanonicalHostName());//获取此IP地址的完全限定域名
System.out.println(inetAddress2.getHostAddress());//返回ip地址字符串
System.out.println(inetAddress2.getHostName());//获取此IP地址的主机名
} 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,端口号用来区分软件
- 端口号被规定为0~65535
- TCP,UDP:每个协议都为0~65535范围;在相同的协议下,端口号不可以重复;在不同的协议下,端口号可以重复
- 端口的分类
- 共有端口0-1023
- HTTP:80
- HTTPS:443
- FTP:21
- TELNET:23
- 程序注册端口:1024-49151粉嫩配给用户或程序
- Tomcat:8080
- MySQL:3306
- Oracle:1521
- 动态、私有的端口:49152——65535
- 共有端口0-1023
cmd查看端口号的命令:
netstat -ano 查看所有的端口
netstat -ano|findstr "5900" 查看指定的端口号
tasklist|findstr "8696" 查看指定端口的进程
Ctrl+shift+ESC:打开任务管理器
InetSocketAddress类
这个类实现一个IP套接字地址(IP地址+端口号),它也可以是一对(主机名+端口号),在这种情况下,将尝试解析主机名。
package mynet;
import java.net.InetSocketAddress;
public class TestInetSocketAddress01 {
public static void main(String[] args) {
InetSocketAddress inetSocketAddress1 = new InetSocketAddress("127.0.0.1",8080);
System.out.println(inetSocketAddress1);
InetSocketAddress inetSocketAddres2 = new InetSocketAddress("localhost", 8080);
System.out.println(inetSocketAddres2);
System.out.println(inetSocketAddres2.getAddress());//IP地址
System.out.println(inetSocketAddres2.getPort());//端口
System.out.println(inetSocketAddres2.getHostName());//主机名
}
}
通信协议
协议:约定,好比我们现在说的普通话
网络通信协议:速率,传输码率,代码结构,传输控制......
问题:十分复杂?
大事化小:分层!
TCP/IP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
出名的协议:
- TCP:用户传输协议
- IP:网络互连协议
TCP和UDP的对比
TCP:打电话
- 连接,稳定
- 三次握手 四次挥手
三次握手,建立连接
最少需要三次,保证稳定连接
A:你瞅啥?
B:瞅你咋地?
A:干一场!
四次挥手,断开连接
A:我要走了!
B:你真的要走了吗?
B:你真的真的要走了吗?
A:我真的要走了!
- 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,都可以发给你
TCP协议
客户端
1.连接服务器 Socket
2.发送消息
package mynet;
import java.io.IOException;
import java.io.OutputStream;
import java.net.Socket;
//客户端
public class TcpClientDemo01 {
public static void main(String[] args) {
try ( //连接服务器端口
Socket socket = new Socket("localhost", 9900);
//发送消息 IO流
OutputStream outputStream = socket.getOutputStream();){
outputStream.write("hello, world".getBytes());
} catch (IOException e) {
e.printStackTrace();
}
}
}
服务器
1.建立服务器的端口 ServiceSocket
2.等待用户的连接accept
3.接收用户的消息
package mynet;
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 TcpServiceDemo01 {
public static void main(String[] args) {
try (//创建服务器的端口
ServerSocket serverSocket = new ServerSocket(9900);
//接收客户端请求
Socket accept = serverSocket.accept();//与客户端socket对象相对应
//读取客户端消息
InputStream inputStream = accept.getInputStream();
//管道流
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
){
byte[] buffer = new byte[1024];
int len = 0;
while ((len = inputStream.read(buffer)) != -1){
byteArrayOutputStream.write(buffer,0,len);
}
System.out.println(byteArrayOutputStream.toString());
} catch (IOException e) {
e.printStackTrace();
}
}
}
TCP文件上传实现
客户端:
package mynet;
import javax.lang.model.element.VariableElement;
import java.io.*;
import java.net.InetAddress;
import java.net.Socket;
public class TcpClientDemo02 {
public static void main(String[] args) {
try (//连接服务器
Socket socket = new Socket(InetAddress.getByName("localhost"), 8888);
//发送请求
OutputStream outputStream = socket.getOutputStream();
FileInputStream fileInputStream = new FileInputStream("C:\\test\\头像1.jpg");
//接收服务器端 的消息
InputStream inputStream = socket.getInputStream();
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();){
byte[] buffer = new byte[1024];
int len = 0;
while ((len = fileInputStream.read(buffer)) != -1){
outputStream.write(buffer,0,len);
}
//通知服务器,我已经接受完毕
socket.shutdownOutput();//如果没有这步,服务器一直在接收数据,停不下来
//接收服务器端 的消息
byte[] buffer2 = new byte[1024];
int len2 =0;
while ((len2 = inputStream.read(buffer2)) != -1){
byteArrayOutputStream.write(buffer2,0,len2);
}
System.out.println(byteArrayOutputStream.toString());
} catch (IOException e) {
e.printStackTrace();
}
}
}
服务器端:
package mynet;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
public class TcpServerDemo02 {
public static void main(String[] args) {
try (//创建服务器IP,端口号
ServerSocket serverSocket = new ServerSocket(8888);
//接受请求
Socket accept = serverSocket.accept();
InputStream inputStream = accept.getInputStream();
FileOutputStream fileOutputStream = new FileOutputStream("C:\\test\\复制头像111.jpg");
//通知客户端接收完毕
OutputStream outputStream = accept.getOutputStream();){
byte[] buffer = new byte[1024];
int len = 0;
while ((len = inputStream.read(buffer))!=-1){
fileOutputStream.write(buffer,0,len);
}
//通知客户端接收完毕
outputStream.write("我接收完毕了".getBytes());
} catch (IOException e) {
e.printStackTrace();
}
}
}
Tomcat服务器
服务器
- 自定义service
- Tomcat服务器 service:Java后台开发
客户端
- 自定义client
- 浏览器browser
UDP
发短信:不用连接,需要知道对方的地址
UDP协议发送和接收消息:
发送端:
package mynet;
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 UdpClientDemo01 {
public static void main(String[] args) throws Exception {
//建立一个socket连接
DatagramSocket datagramSocket = new DatagramSocket();
//建立数据包
String str = "你好啊";
DatagramPacket packet = new DatagramPacket(str.getBytes(),0,str.getBytes().length, InetAddress.getByName("localhost"),9090);
//发送数据包
datagramSocket.send(packet);
//关闭连接
datagramSocket.close();
}
}
接收端:
package mynet;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
//还是要等待对方的连接
public class UdpServerDemo01 {
public static void main(String[] args) throws IOException {
//建立一个socket连接
DatagramSocket datagramSocket = new DatagramSocket(9090);
//接受数据包
byte[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);
datagramSocket.receive(packet);//阻塞接收
System.out.println(packet.getAddress());
System.out.println(new String(packet.getData()));
//关闭连接
datagramSocket.close();
}
}
循环发送消息
package mynet;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
public class TcpSender01 {
public static void main(String[] args) throws IOException {
DatagramSocket socket = new DatagramSocket(6666);
while (true){
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
String data = bufferedReader.readLine();
DatagramPacket packet = new DatagramPacket(data.getBytes(), 0, data.getBytes().length, InetAddress.getByName("localhost"), 8888);
socket.send(packet);
if (data.equals("bye")){
break;
}
}
}
}
循环接收消息
package mynet;
import java.io.IOException;
import java.net.*;
public class TcpReceiver01 {
public static void main(String[] args) throws IOException {
DatagramSocket socket = new DatagramSocket(8888);
while (true){
byte[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length, InetAddress.getByName("localhost"), 6666);
socket.receive(packet);
String receiveData = new String(packet.getData());
System.out.println(receiveData);
if (receiveData.equals("bye")){
break;
}
}
}
}
在线咨询:两人都可以是发送方,也都可以是接收方
UDP多线程在线咨询
package mynet;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.*;
public class TalkSend implements Runnable{
private DatagramSocket socket = null;
private BufferedReader bufferedReader = null;
private DatagramPacket packet = 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(fromPort);
bufferedReader = new BufferedReader(new InputStreamReader(System.in));
} catch (SocketException e) {
e.printStackTrace();
}
}
@Override
public void run() {
while (true){
try {
String data = bufferedReader.readLine();
packet = new DatagramPacket(data.getBytes(),0,data.getBytes().length,new InetSocketAddress(toIp,toPort));
socket.send(packet);
if (data.equals("bye")){
break;
}
} catch (IOException e) {
e.printStackTrace();
}
}
socket.close();
}
}
package mynet;
import java.io.IOException;
import java.net.*;
public class TalkRecieve implements Runnable{
private DatagramSocket socket = null;
private int port;
private String msgFrom;
public TalkRecieve(int port, String msgFrom) {
this.port = port;
this.msgFrom = msgFrom;
try {
socket = new DatagramSocket(this.port);
} catch (SocketException e) {
e.printStackTrace();
}
}
@Override
public void run() {
while (true){
try {
byte[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);;
socket.receive(packet);
String receiveData = new String(packet.getData());
System.out.println(this.msgFrom+":"+receiveData);
if (receiveData.equals("bye")){
break;
}
} catch (IOException e) {
e.printStackTrace();
}
}
socket.close();
}
}
package mynet;
public class StudentTalk {
public static void main(String[] args) {
new Thread(new TalkSend(6666,"localhost",5555)).start();
new Thread(new TalkRecieve(9999,"老师")).start();
}
}
package mynet;
public class TeacherTalk {
public static void main(String[] args) {
new Thread(new TalkRecieve(5555,"学生")).start();
new Thread(new TalkSend(8888,"localhost",9999)).start();
}
}
URL
URL:统一资源定位符:定位资源的,定位互联网上的某一个资源
DNS域名解析 www.baidu.com这----》ip地址xxxx.xxx.....xxx
格式:(只能少,不能多)
协议://ip地址:端口/项目名/资源
package mynet;
import java.net.MalformedURLException;
import java.net.URL;
public class TestURL01 {
public static void main(String[] args) throws MalformedURLException {
URL url = new URL("https://www.bilibili.com/video/BV1LJ411z7vY?p=12");
System.out.println(url.getProtocol());//协议
System.out.println(url.getHost());//主机ip
System.out.println(url.getPort());//端口号
System.out.println(url.getPath());//文件路径
System.out.println(url.getFile());//文件全路径
System.out.println(url.getQuery());//传递的参数
}
}
package mynet;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
//下载网络上的资源
public class TestURL02 {
public static void main(String[] args) {
try {
//下载地址
URL url = new URL("http://antiserver.kuwo.cn/anti.s?rid=MUSIC_40076906&response=res&format=mp3|aac&type=convert_url&br=128kmp3&agent=iPhone&callback=getlink&jpcallback=getlink.mp3");
//连接资源 HTTP
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
InputStream inputStream = connection.getInputStream();
FileOutputStream fos = new FileOutputStream("src\\mynet\\贝加尔湖畔-李健.mp3");
byte[] buffer = new byte[1024];
int len = 0;
while ((len = inputStream.read(buffer)) != -1){
fos.write(buffer,0,len);
}
fos.close();
inputStream.close();
connection.disconnect();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}