java - 如何在java中通过UDP数据报发送字符串数组？

Question

我用 java 编写了一个程序，用于从数据库检索数据并将其存储在名为 Records 的字符串数组中。该程序将String msg发送到包含测试客户端的服务器。您能否告诉我如何发送String [] Records而不是字符串消息？..

感谢您的帮助谢谢您

这是程序:

import java.io.*;
import java.net.*;
import java.sql.*;

public class Client {

public static void main(String[] args) {
String [] Records= new String[5];
 int x = 1;
 while (true){
        try {

            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            Connection con = DriverManager.getConnection("jdbc:odbc:DDS_DSN");
            Statement st = con.createStatement();



            PreparedStatement ps = con.prepareStatement(
                    "SELECT * FROM request_dns " +
                    "WHERE id = ?");
            ps.setInt(1, x);
ResultSet rs = ps.executeQuery();


            while ( rs.next() ) {
                Records[0]= rs.getString("id");
                Records[1]= rs.getString("source_ip");
                Records[2]= rs.getString("source_port");
                Records[3]= rs.getString("destination_ip");
                Records[4]= rs.getString("destination_port");

                System.out.println(Records[0]);
                System.out.println(Records[1]);
                System.out.println(Records[2]);
                System.out.println(Records[3]);
                System.out.println(Records[4]);
            }
            con.close();
        } catch (Exception e) {
            System.out.println(e);

        }


        DatagramSocket skt;

        try{

        skt =new DatagramSocket();
        String msg ="test client"; ///////////////// sent messege
        byte [] b = msg.getBytes();
        InetAddress host=InetAddress.getByName("localhost"); ///////// inserting the destination IP address

        int serverSocket =6700; ///////////////////port number

        ////////////////////////////////packet sender
        DatagramPacket request = new DatagramPacket (b,b.length,host,serverSocket);
        skt.send (request);

        /////////////////////packet receiver
       byte [] buffer = new byte [1000];
        DatagramPacket reply = new DatagramPacket (buffer,buffer.length);
        skt.receive(reply);
        System.out.println("client received \t"+new String(reply.getData()) );

        skt.close();




        }

        catch(Exception ex){

        }

x++;
}
    }

}

Answer 1

有很多很多方法可以做到这一点，但也许最简单的是将多个字符串转换为一个字符串，然后再转换回来。这样您的其余代码就会像现在一样。

String[] array = "a,b,c,d,e".split(",");
// to join multiple strings into one.
String s = Stream.of(array).collect(Collectors.joining(","));
// to split multiple strings from on.
String[] array2 = s.split(",");

您可能会找到更好的分隔符，例如 "|" 或 "\uffff"，具体取决于您使用的编码。

注意:UDP 是一种有损协议(protocol)，这意味着无法保证会收到数据包，并且发送方无法知道这已经发生。您可以添加协议(protocol)来减少传输损耗，但是使用执行此操作的现有库或 TCP 通常更简单。