java6-网络通信

1，几个常用类

• 服务器端socket：ServerSocket
• 客户端socket：Socket
• IP地址：InetAddress

2，简单的聊天对话系统

//服务器端
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

public class simpleServer {
    public static final int SERVER_PORT = 40000;
    public static final Charset SERVER_CHARSET = StandardCharsets.UTF_8;
    public static final String BYE = "bye";

    public static void main(String[] args) throws IOException {
        talkWithClient();
    }

    private static void talkWithClient() throws IOException {
        System.out.println("Server启动，在端口 " + SERVER_PORT + " 监听。。。");
        try(
            ServerSocket ss = new ServerSocket(SERVER_PORT);    //监听端口
            Socket s = ss.accept(); //建立连接
        ){
            Chat chat = new Chat("客户端", "成功建立连接", s);
            chat.chatting();
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

//客户端
import java.io.IOException;
import java.net.Socket;

public class simpleClinet {
    public static void main(String[] args) throws IOException {
        talkWithServer();
    }

    private static void talkWithServer() throws IOException {
        try(
                //localhost == 127.0.0.1 == 本机IP
            Socket socket = new Socket("localhost", simpleServer.SERVER_PORT);
        ){
            Chat chat = new Chat("服务器端", null, socket);
            chat.chatting();
        } catch (Exception e){
            e.printStackTrace();
        }
    }
}

//对话类
import java.io.*;
import java.net.Socket;
import java.util.Scanner;

public class Chat {

    private String from;
    private String greetings;
    private Socket socket;

    public Chat(String from, String greetings, Socket socket){
        this.from = from;
        this.greetings = greetings;
        this.socket = socket;
    }

    public void chatting() throws IOException {
        Scanner sc = new Scanner(System.in);

        try(
            BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream(), simpleServer.SERVER_CHARSET));
            PrintWriter pw = new PrintWriter(new OutputStreamWriter(socket.getOutputStream(), simpleServer.SERVER_CHARSET));
        ){
            System.out.println("Socket连接成功！");
            if(greetings!=null){
                pw.println("你好，" + from + "。 " + greetings);
                pw.flush();
            }
            while (true){
                String line = br.readLine();
                if(line.trim().equalsIgnoreCase(simpleServer.BYE)){
                    System.out.println("对方要求断开连接！");
                    pw.println(simpleServer.BYE);
                    pw.flush();
                    break;
                }else{
                    System.out.println("来自 "+from+" 的消息："+line);
                }
                line = sc.nextLine();
                pw.println(line);
                pw.flush();
            }
        }catch (Exception e){
            e.printStackTrace();
        }
        System.out.println("聊天结束。");
    }

}

3，简单的聊天系统-V2-不用chat类

//服务器端
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.Scanner;

public class simpleServer {
    public static final int SERVER_PORT = 40000;
    public static final Charset SERVER_CHARSET = StandardCharsets.UTF_8;
    public static final String BYE = "bye";

    public static void main(String[] args) throws IOException {
        talkWithClient();
    }

    static void talkWithClient() throws IOException {
        try(
            ServerSocket ss = new ServerSocket(SERVER_PORT);
            Socket s = ss.accept();
            BufferedReader br = new BufferedReader(
                    new InputStreamReader(s.getInputStream(), SERVER_CHARSET));
            PrintWriter pw = new PrintWriter(
                    new OutputStreamWriter(s.getOutputStream(), SERVER_CHARSET));
            Scanner sc = new Scanner(System.in);
        ){
            System.out.println("成功建立连接！" + s.getRemoteSocketAddress());
            while(true){
                String line = br.readLine();
                if(line.trim().equalsIgnoreCase(BYE)){
                    pw.println(BYE);
                    pw.flush();
                    System.out.println("断开连接！");
                    break;
                }else{
                    System.out.println(line);
                    pw.println(sc.nextLine());
                    pw.flush();
                }
            }
        }catch (Exception e){
            e.printStackTrace();
        }
    }

}

//客户端
import java.io.*;
import java.net.Socket;
import java.util.Scanner;

public class simpleClinet {
    public static void main(String[] args) throws IOException {
        talkWithServer();
    }

    static void talkWithServer() throws IOException {
        try(
            Socket s = new Socket("localhost", simpleServer.SERVER_PORT);
            BufferedReader br = new BufferedReader(
                    new InputStreamReader(s.getInputStream(), simpleServer.SERVER_CHARSET));
            PrintWriter pw = new PrintWriter(
                    new OutputStreamWriter(s.getOutputStream(), simpleServer.SERVER_CHARSET));
            Scanner sc = new Scanner(System.in);
        ){
            System.out.println("链接到服务器："+s.getRemoteSocketAddress());
            while (true){
                pw.println(sc.nextLine());
                pw.flush();
                String line = br.readLine();
                if(line.trim().equalsIgnoreCase(simpleServer.BYE)){
                    pw.println(simpleServer.BYE);
                    pw.flush();
                    System.out.println("断开连接！");
                    break;
                }else {
                    System.out.println(line);
                }
            }
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

4，简单抓取网页内容

import java.io.*;
import java.net.*;
import java.nio.charset.StandardCharsets;

public class getHtmlContentAppMain {
    public static void main(String[] args) throws IOException {
        //域名解析
        InetAddress inetAddress = InetAddress.getByName("www.baidu.com");
        System.out.println("网站IP地址为："+inetAddress);

        //连接服务器
        Socket s = new Socket();
        SocketAddress sa = new InetSocketAddress(inetAddress, 80);
        s.connect(sa, 10000);   //10000为连接时限
        System.out.println("连接到服务器");

        //发送HTTP请求
        PrintWriter pw = new PrintWriter(
                new OutputStreamWriter(s.getOutputStream(), StandardCharsets.UTF_8));
        StringBuffer sb = new StringBuffer();
        sb.append("GET /index.html HTTP/1.1\r\n");
        sb.append("Host: www.baidu.com\r\n");
        sb.append("Connection: Keep-Alive\r\n");
        sb.append("\r\n");
        pw.println(sb.toString());
        pw.flush();

        //接收返回值
        BufferedReader br = new BufferedReader(
                new InputStreamReader(s.getInputStream(), StandardCharsets.UTF_8));
        br.lines().forEach(System.out::println);
    }
}