Day38 网络编程(了解即可)
1. 计算机网络
2. 网络编程
实现多台计算机之间实现数据的共享和传递,网络应用程序主要组成为:网络编程+IO流+多线程
3. 网络模型
两台计算机之间的通信是根据什么规则来走的(OSI & TCP/IP)
此处简单了解该模型就行《TCP/IP详解》《TCP协议簇》
4. 网络编程三要素
网络通讯的模型:请求-响应,客户端-服务端
三要素:IP地址,端口,协议(数据传输的规则)
4.1. IP地址
理解:网络中计算机的唯一标识(IP地址是一个32位的二进制数据)
注意:127.0.0.1表示本机地址
4.2. 端口号
理解:应用程序在电脑上的唯一标识
每个网络程序都会至少有一个逻辑端口
用于标识进程的逻辑地址,不同进程的标识不同
有效端口:065535,其中01024系统使用或保留端口。
注意:端口与协议有关:TCP和UDP的端口互不相干,同一个协议的端口不能重复,不同协议的可以重复
4.3. 网络协议
理解:通信规则,就是数据的传输规则
TCP:建立连接,形成传输数据的通道;在连接中进行大数据量传输;通过三次握手完成连接,是可靠协议;必须建立连接,效率会稍低,例如:打电话
UDP:将数据源和目的封装到数据包中,不需要建立连接;每个数据报的大小在限制在64k;因无连接,是不可靠协议;不需要建立连接,速度快:例如发短信
HTTP…
5. InetAddress类
理解:用来表示主机的信息
注意:一个域名 对应 多个IP地址
public class Test01 {
public static void main(String[] args) throws UnknownHostException {
//获取本机的IP地址
// InetAddress localHost = InetAddress.getLocalHost();
// System.out.println(localHost);
//获取域名对应的服务器地址
// InetAddress byName = InetAddress.getByName("www.baidu.com");
// System.out.println(byName);
//获取域名对应的所有的服务器地址
InetAddress[] allByName = InetAddress.getAllByName("www.baidu.com");
for (InetAddress inetAddress : allByName) {
System.out.println(inetAddress);
}
}
}
6. Socket
Scoket也叫套接字,其表示的是IP地址和端口号的组合。
网络编程主要就是指Socket编程,网络间的通信其实就是Socket间的通信,数据就通过IO流在两个Scoket间进行传递。
7. TCP编程
理解:客户端(发送一个请求),服务端(接收到这个请求,给予响应)
API:Socket,ServerSocket
7.1. 简单的TCP通信
编写服务端程序
//服务端
public class Server {
public static void main(String[] args) throws IOException {
//大堂经理
ServerSocket server = new ServerSocket(8080);
//18号技师
//注意:accept()是线程阻塞的方法,该方法会等待客户端的连接成功后才生成一个Socket对象与之交互
Socket socket = server.accept();
//2.接受来自客户端的数据
BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream(), "GBK"));
String readLine = br.readLine();
System.out.println(readLine);
//3.向客户端发送数据
PrintStream ps = new PrintStream(socket.getOutputStream());
ps.println("18号技师:今年18岁");
br.close();
ps.close();
server.close();
}
}
编写客户端程序
//客户端
public class Client {
public static void main(String[] args) throws UnknownHostException, IOException {
//注意:关闭流相当于关闭Socket!!!
//巴得伟
Socket socket = new Socket("127.0.0.1", 8080);
//1.向服务端发送数据
PrintStream ps = new PrintStream(socket.getOutputStream());
ps.println("巴得伟:小妹妹,你多大了?");
//4.接受来自服务端的数据
BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream(), "GBK"));
String readLine = br.readLine();
System.out.println(readLine);
ps.close();
br.close();
socket.close();
}
}
注意:先运行服务程序,再运行客户端程序
7.2 TCP案例
7.2.1 传输文件
服务端
public class Server {
public static void main(String[] args) throws IOException {
ServerSocket server = new ServerSocket(8080);//端口号要对应
Socket socket = server.accept();
BufferedInputStream bis = new BufferedInputStream(socket.getInputStream());
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("copy.mp4"));
byte[] bs = new byte[1024];
int len;
while((len = bis.read(bs)) != -1){
bos.write(bs, 0, len);
}
bis.close();
bos.close();
server.close();
}
}
客户端
public class Client {
public static void main(String[] args) throws UnknownHostException, IOException {
Socket socket = new Socket("127.0.0.1", 8080);
BufferedInputStream bis = new BufferedInputStream(new FileInputStream("视频.mp4"));
BufferedOutputStream bos = new BufferedOutputStream(socket.getOutputStream());
byte[] bs = new byte[1024];
int len;
while((len = bis.read(bs)) != -1){
bos.write(bs, 0, len);
}
bis.close();
bos.close();
socket.close();
}
}
7.2.2 单聊
public class Server {
public static void main(String[] args) throws IOException {
ServerSocket server = new ServerSocket(8080);
Socket socket = server.accept();
new ReceiveThread(socket).start();
Scanner scan = new Scanner(System.in);
PrintStream ps = new PrintStream(socket.getOutputStream());
while(true){
ps.println("18号技师:" + scan.next());
}
}
}
public class Client {
public static void main(String[] args) throws UnknownHostException, IOException {
Socket socket = new Socket("127.0.0.1", 8080);
new ReceiveThread(socket).start();
Scanner scan = new Scanner(System.in);
PrintStream ps = new PrintStream(socket.getOutputStream());
while(true){
ps.println("巴得伟:" + scan.next());
}
}
}
接收消息的多线程
public class ReceiveThread extends Thread{
private Socket socket;
public ReceiveThread(Socket socket) {
this.socket = socket;
}
@Override
public void run() {
try {
BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream(), "GBK"));
while(true){
String readLine = br.readLine();
System.out.println(readLine);
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
7.2.3 群聊
public class Server {
public static final ConcurrentHashMap<String, PrintStream> map = new ConcurrentHashMap<>();
public static void main(String[] args) throws IOException {
ServerSocket server = new ServerSocket(8080);
while(true){
Socket socket = server.accept();
String ip = socket.getInetAddress().toString();
PrintStream ps = new PrintStream(socket.getOutputStream());
map.put(ip, ps);
new ServerThread(socket).start();
}
}
}
public class Client {
public static void main(String[] args) throws UnknownHostException, IOException {
Socket socket = new Socket("127.0.0.1", 8080);
new ReceiveThread(socket).start();
Scanner scan = new Scanner(System.in);
PrintStream ps = new PrintStream(socket.getOutputStream());
while(true){
ps.println("巴得伟:" + scan.next());
}
}
}
public class ReceiveThread extends Thread{
private Socket socket;
public ReceiveThread(Socket socket) {
this.socket = socket;
}
@Override
public void run() {
try {
BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream(), "GBK"));
while(true){
String readLine = br.readLine();
System.out.println(readLine);
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
public class ServerThread extends Thread{
private Socket socket;
public ServerThread(Socket socket) {
this.socket = socket;
}
@Override
public void run() {
try {
//接受当前客户端的消息
BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream(), "GBK"));
while(true){
String readLine = br.readLine();
System.out.println(readLine);
//发送给其他客户端消息
Set<Entry<String,PrintStream>> entrySet = Server.map.entrySet();
for (Entry<String, PrintStream> entry : entrySet) {
String ip = entry.getKey();
PrintStream ps = entry.getValue();
if(!socket.etInetAddress().toString().equals(ip)){
ps.println(readLine);
}
}
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
8.TCP三次握手 和 四次挥手
9. UDP编程
UDP用户数据报包协议,UDP和TCP位于同一层----传输层,但它对于数据包的顺序错误或重发没有TCP可靠;UDP是一种面向无连接的通信协议。UDP向应用程序提供一种发送封装的原始IP数据报的方法,并且发送时无需建立连接,不保证可靠数据的传输
UDP — 发短信
TCP — 打电话
9.1 简单的UDP通信
注意:
1.UDP协议的Socket是DatagramSocket
2.7070表示的是自己的端口号,不是对方的端口号
public class Client01 {
public static void main(String[] args) throws IOException {
DatagramSocket socket = new DatagramSocket(7070);
//1.向客户端2发送数据
byte[] buf = "用良心做教育".getBytes();
DatagramPacket p = new DatagramPacket(buf , 0, buf.length, InetAddress.getByName("127.0.0.1"), 8080);
socket.send(p);
//4.接受来自客户端1的数据
buf = new byte[1024];
p = new DatagramPacket(buf , buf.length);
socket.receive(p);
System.out.println(new String(buf).trim());
socket.close();
}
}
public class Client02 {
public static void main(String[] args) throws IOException {
DatagramSocket socket = new DatagramSocket(8080);
//2.接受来自客户端1的数据
byte[] buf = new byte[1024];
DatagramPacket p = new DatagramPacket(buf , buf.length);
socket.receive(p);
System.out.println(new String(buf).trim());
//3.向客户端2发送数据
buf = "做真实的自己".getBytes();
p = new DatagramPacket(buf , 0, buf.length, InetAddress.getByName("127.0.0.1"), 7070);
socket.send(p);
socket.close();
}
}
9.2 UDP案例 之 单聊
public class Client01 {
public static void main(String[] args) throws SocketException {
DatagramSocket socket = new DatagramSocket(7070);
new ReceiveThread(socket).start();
new SendThread("巴得伟", "127.0.0.1", 8080, socket).start();
}
}
public class Client02 {
public static void main(String[] args) throws SocketException {
DatagramSocket socket = new DatagramSocket(8080);
new ReceiveThread(socket).start();
new SendThread("王益升", "127.0.0.1", 7070, socket).start();
}
}
public class ReceiveThread extends Thread{
private DatagramSocket socket;
public ReceiveThread(DatagramSocket socket) {
this.socket = socket;
}
@Override
public void run() {
while(true){
byte[] buf = new byte[1024];
DatagramPacket p = new DatagramPacket(buf , buf.length);
try {
socket.receive(p);
System.out.println(new String(buf).trim());
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
public class SendThread extends Thread{
private String nickName;
private String ip;
private int port;
private DatagramSocket socket;
public SendThread(String nickName, String ip, int port, DatagramSocket socket) {
this.nickName = nickName;
this.ip = ip;
this.port = port;
this.socket = socket;
}
@Override
public void run() {
Scanner scan = new Scanner(System.in);
while(true){
byte[] buf = (nickName + ":" + scan.next()).getBytes();
try {
DatagramPacket p = new DatagramPacket(buf, buf.length, InetAddress.getByName(ip), port);
socket.send(p);
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
9.3 TCP VS UDP
比较 | TCP | UDP |
---|---|---|
是否连接 | 面向连接 | 无面向连接 |
传输可靠性 | 可靠 | 不可靠 |
应用场合 | 传输大量数据 | 少量数据 |
速度 | 慢 | 快 |
10.HTTP
请求–resquest
响应–response
10.1 需求:获取淘宝商品周边类别
public class Test01 {
public static void main(String[] args) throws IOException {
String path = "https://suggest.taobao.com/sug?code=utf-8&q=%E8%80%90%E5%85%8B&callback=cb";
//创建链接对象
URL url = new URL(path);
//获取连接对象
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
//设置参数
connection.setConnectTimeout(5000);//设置连接超时时间
connection.setReadTimeout(5000);//设置读取数据超时时间
connection.setDoInput(true);//设置是否允许使用输入流
connection.setDoOutput(true);//设置是否允许使用输出流
//获取响应状态码
int code = connection.getResponseCode();
if(code == HttpURLConnection.HTTP_OK){
BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream(),"UTF-8"));
char[] cs = new char[1024];
int len;
while((len = br.read(cs)) != -1){
System.out.println(new String(cs, 0, len));
}
}else if(code == HttpURLConnection.HTTP_NOT_FOUND){
System.out.println("页面未找到");
}
}
}
10.2 需求:下载图片
public class Test02 {
public static void main(String[] args) throws IOException {
String path = "https://wx2.sinaimg.cn/mw690/e2438f6cly1hoo3qpm7vrj21111jk4mn.jpg";
//创建链接对象
URL url = new URL(path);
//获取连接对象
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
//设置参数
connection.setConnectTimeout(5000);//设置连接超时时间
connection.setReadTimeout(5000);//设置读取数据超时时间
connection.setDoInput(true);//设置是否允许使用输入流
connection.setDoOutput(true);//设置是否允许使用输出流
//获取响应状态码
int code = connection.getResponseCode();
if(code == HttpURLConnection.HTTP_OK){
BufferedInputStream bis = new BufferedInputStream(connection.getInputStream());
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("金智媛.jpg"));
byte[] bs = new byte[1024];
int len;
while((len = bis.read(bs)) != -1){
bos.write(bs, 0, len);
}
bis.close();
bos.close();
}else if(code == HttpURLConnection.HTTP_NOT_FOUND){
System.out.println("页面未找到");
}
}
}