文章目录
- InetAddress
- 端口
- InetSocketAddress
- URL
- 获取网页代码 爬虫
- 传输协议 UDP TCP
- 聊天室示例
InetAddress
- 创建InetAddress对象,从本地,ip,或者域名创建
import java.net.InetAddress;
import java.net.UnknownHostException;
public class TestIP {
public static void main(String[] args) throws UnknownHostException {
InetAddress addr = InetAddress.getLocalHost();
System.out.println(addr.getHostAddress());
System.out.println(addr.getHostName());
addr = InetAddress.getByName("www.baidu.com");
System.out.println(addr.getHostAddress());
System.out.println(addr.getHostName());
addr = InetAddress.getByName("39.156.66.14"); System.out.println(addr.getHostAddress());
System.out.println(addr.getHostAddress());
System.out.println(addr.getHostName());
}
}
端口
- 两个字节,0-65535,区分一个电脑的不同网络应用程序
- 公认端口0-1023,注册端口1024-49151,私有端口49152-65535
- 8080,Tomcat的端口,1521,Oracle,3306,mysql
- windows下查看端口,netstat -ano命令。
- 过滤端口 netstat -ano | findstr “808”
- 查找应用程序 tasklist | findstr “808”
InetSocketAddress
- new InetSocketAddress(地址|域名,端口);
import java.net.InetSocketAddress;
public class TestSocketAddress {
public static void main(String[] args) {
InetSocketAddress address = new InetSocketAddress("127.0.0.1",8080);
InetSocketAddress address1 = new InetSocketAddress("www.baidu.com",8080);
System.out.println(address.getHostName());
System.out.println(address.getAddress());
System.out.println(address.getPort());
}
}
URL
- URI 统一资源标识符
- URL 统一资源定位符
- URN 统一资源名称
- http默认端口是80
import java.net.MalformedURLException;
import java.net.URL;
public class TestURL {
public static void main(String[] args) throws MalformedURLException {
URL url = new URL("https://www.baidu.com/s?ie=utf-8&f=8&rsv_bp=1&rsv_idx=2&tn=baiduhome_pg&wd=java&rsv_spt=1&oq=%2526lt%253B9.156.66.14&rsv_pq=98b4ebc900033cdd&rsv_t=b50aYzbLYicGgZtJnHCgENvOQx0v6JlZvtmGJ7GOiPllohOtrF0K0Us6S%2BEA6nMWh9xF&rqlang=cn&rsv_enter=1&rsv_dl=tb&rsv_sug3=6&rsv_sug2=0&prefixsug=java&rsp=3&inputT=1104&rsv_sug4=10013020");
System.out.println("协议:"+url.getProtocol());
System.out.println("域名:"+url.getHost());
System.out.println("端口:"+url.getPort());
System.out.println("请求资源:"+url.getFile());
System.out.println("请求资源1:"+url.getPath());
System.out.println("参数:"+url.getQuery());
System.out.println("锚点:"+url.getRef());
}
}
获取网页代码 爬虫
- 获取网页代码,使用HttpURLConnection模拟浏览器登录。谷歌浏览器打开网页,F12,查看请求信息
- 获取信息后还要经过进一步的处理

package MyPro12;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
public class TestSpider {
public static void main(String[] args) throws Exception {
URL url = new URL("https://www.dianping.com");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("User-Agent","Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36");
BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream(),"UTF-8"));
String msg = null;
while ((msg = br.readLine())!=null){
System.out.println(msg);
}
br.close();
}
public void test()throws Exception{
URL url = new URL("https://www.jd.com");
InputStream is = url.openStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is,"UTF-8"));
String msg = null;
while ((msg = br.readLine())!=null){
System.out.println(msg);
}
br.close();
}
}
传输协议 UDP TCP
- TCP 面向连接,比较可靠的字节流通信,占用资源多,效率低
- UDP 非面向连接不可靠,收到也不确认,非常简单,开销小
- 套接字 socket,socket连接传输层和应用层
- socket编程
UDP
- DatagramSocket,用于接收或发送的套接字
- DatagramPacket数据包
- 仅基于该数据包中包含的信息,每个消息从一台机器路由到另一台机器。 从一台机器发送到另一台机器的多个分组可能会有不同的路由,并且可能以任何顺序到达。
- udp示例,先开启接受端,再开启发送。接收端的端口,与发送端的InetSocketAddress端口一致。
- 发送端,发送数据,字节数组
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketException;
public class UdpClient {
public static void main(String[] args) throws Exception {
System.out.println("发送方启动....");
DatagramSocket client = new DatagramSocket(9998);
String data = "武汉加油";
byte[] datas = data.getBytes();
DatagramPacket packet = new DatagramPacket(datas,0,datas.length,
new InetSocketAddress("localhost",9999));
client.send(packet);
System.out.println("发送完毕");
client.close();
}
}
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
public class UdpServer {
public static void main(String[] args) throws Exception {
System.out.println("接收端....");
DatagramSocket server = new DatagramSocket(9999);
byte[] container = new byte[1024*60];
DatagramPacket packet= new DatagramPacket(container,0,container.length);
server.receive(packet);
byte[] data = packet.getData();
int len = packet.getLength();
System.out.println("收到数据:\n" + new String(data,0,len));
server.close();
}
}
聊天室示例
- 某个客户端发送消息,其他所有人都能收到,或者给指定人发送消息
- Chat.java 服务端。核心部分
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.CopyOnWriteArrayList;
public class Chat {
private static CopyOnWriteArrayList<Channel> all =new CopyOnWriteArrayList<Channel>();
public static void main(String[] args) throws IOException {
System.out.println("-----Server-----");
ServerSocket server =new ServerSocket(8888);
while(true) {
Socket client =server.accept();
System.out.println("一个客户端建立了连接");
Channel c =new Channel(client);
all.add(c);
new Thread(c).start();
}
}
static class Channel implements Runnable{
private DataInputStream dis;
private DataOutputStream dos;
private Socket client;
private boolean isRunning;
private String name;
public Channel(Socket client) {
this.client = client;
try {
dis = new DataInputStream(client.getInputStream());
dos =new DataOutputStream(client.getOutputStream());
isRunning =true;
this.name =receive();
this.send("欢迎你的到来");
sendOthers(this.name+"来了shsxt聊天室",true);
} catch (IOException e) {
System.out.println("---1------");
release();
}
}
private String receive() {
String msg ="";
try {
msg =dis.readUTF();
} catch (IOException e) {
System.out.println("---2------");
release();
}
return msg;
}
private void send(String msg) {
try {
dos.writeUTF(msg);
dos.flush();
} catch (IOException e) {
System.out.println("---3------");
release();
}
}
private void sendOthers(String msg,boolean isSys) {
boolean isPrivate = msg.startsWith("@");
if(isPrivate) {
int idx =msg.indexOf(":");
String targetName = msg.substring(1,idx);
msg = msg.substring(idx+1);
for(Channel other: all) {
if(other.name.equals(targetName)) {
other.send(this.name +"悄悄地对您说:"+msg);
break;
}
}
}else {
for(Channel other: all) {
if(other==this) {
continue;
}
if(!isSys) {
other.send(this.name +"对所有人说:"+msg);
}else {
other.send(msg);
}
}
}
}
private void release() {
this.isRunning = false;
SxtUtils.close(dis,dos,client);
all.remove(this);
sendOthers(this.name+"离开大家庭...",true);
}
@Override
public void run() {
while(isRunning) {
String msg = receive() ;
if(!msg.equals("")) {
sendOthers(msg,false);
}
}
}
}
}
- Client.java 客户端,开启多个模拟多个用户。idea需要在Edit Configuration中勾选Allow parallel run
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Socket;
import java.net.UnknownHostException;
public class Client {
public static void main(String[] args) throws UnknownHostException, IOException {
System.out.println("-----Client-----");
BufferedReader br =new BufferedReader(new InputStreamReader(System.in));
System.out.println("请输入用户名:");
String name =br.readLine();
Socket client =new Socket("localhost",8888);
new Thread(new Send(client,name)).start();
new Thread(new Receive(client)).start();
}
}
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Socket;
public class Send implements Runnable {
private BufferedReader console ;
private DataOutputStream dos;
private Socket client;
private boolean isRunning;
private String name;
public Send(Socket client,String name) {
this.client =client;
console =new BufferedReader(new InputStreamReader(System.in));
this.isRunning = true;
this.name = name;
try {
dos =new DataOutputStream(client.getOutputStream());
send(name);
} catch (IOException e) {
System.out.println("==1==");
this.release();
}
}
@Override
public void run() {
while(isRunning) {
String msg = getStrFromConsole();
if(!msg.equals("")) {
send(msg);
}
}
}
private void send(String msg) {
try {
dos.writeUTF(msg);
dos.flush();
} catch (IOException e) {
System.out.println(e);
System.out.println("===3==");
release();
}
}
private String getStrFromConsole() {
try {
return console.readLine();
} catch (IOException e) {
e.printStackTrace();
}
return "";
}
private void release() {
this.isRunning = false;
SxtUtils.close(dos,client);
}
}
import java.io.DataInputStream;
import java.io.IOException;
import java.net.Socket;
public class Receive implements Runnable {
private DataInputStream dis ;
private Socket client;
private boolean isRunning;
public Receive(Socket client) {
this.client = client;
this.isRunning = true;
try {
dis =new DataInputStream(client.getInputStream());
} catch (IOException e) {
System.out.println("====2=====");
release();
}
}
private String receive() {
String msg ="";
try {
msg =dis.readUTF();
} catch (IOException e) {
System.out.println("====4====");
release();
}
return msg;
}
@Override
public void run() {
while(isRunning) {
String msg =receive();
if(!msg.equals("")) {
System.out.println(msg);
}
}
}
private void release() {
this.isRunning = false;
SxtUtils.close(dis,client);
}
}
import java.io.Closeable;
public class SxtUtils {
public static void close(Closeable... targets ) {
for(Closeable target:targets) {
try {
if(null!=target) {
target.close();
}
}catch(Exception e) {
}
}
}
}