Node.js socket.send() 方法

socket.send()方法是 dgram 模块中 Socket 类的内置应用程序编程接口，用于将消息从一个套接字发送到另一个套接字。

句法：

socket.send(msg[, offset, length][, port][, address][, callback])

参数：此方法采用以下参数：

• msg：要发送的消息。
• offset：消息开始的缓冲区中的偏移量。
• 长度：消息中的字节数。
• 端口：目的端口。
• 地址：目标主机名或 IP 地址。
• callback：消息发送后调用。

返回值：此方法不返回任何值。

示例 1：文件名：index.js

Javascript

// Node.js program to demonstrate the
// server.send() method
 
// Importing dgram module
var dgram = require('dgram');
 
// Creating and initializing client
// and server socket
var client = dgram.createSocket("udp4");
var server = dgram.createSocket("udp4");
 
// Catching the message event
server.on("message", function (msg) {
 
// Displaying the client message
process.stdout.write("UDP String: " + msg + "\n");
 
// Exiting process
process.exit();
})
 
  // Binding server with port
  .bind(1234, () => {
 
  // Getting the reference of the server
  // by using ref() method
  const size = server.ref();
 
  // Display the result
  console.log(size.eventNames());
});
 
// Client sending message to server
// by using send() method
client.send("Hello", 0, 7, 1234, "localhost");

输出：

[ 'message' ]
UDP String: Hello

示例 2：文件名：index.js

Javascript

// Node.js program to demonstrate the
// server.send() method
 
// Importing dgram module
var dgram = require('dgram');
 
// Creating and initializing client
// and server socket
var client = dgram.createSocket("udp4");
var server = dgram.createSocket("udp4");
 
// Catching the message event
server.on("message", function (msg) {
 
  // Displaying the client message
  process.stdout.write("UDP String: " + msg + "\n");
 
  // Exiting process
  process.exit();
});
 
// Catching the listening event
server.on('listening', () => {
 
  // Getting address information for the server
  const address = server.address();
 
  // Display the result
  console.log(
`server listening ${address.address}:${address.port}`);
});
 
 
// Binding server with port address
// by using bind() method
server.bind(1234, () => {
 
  // Getting the reference of server
  // by using ref() method
  const size = server.ref();
 
  // display the result
  console.log(size.eventNames());
});
 
// Client sending message to server
// by using send() method
client.send("Hello", 0, 7, 1234, "localhost", (err) =>{
 
  if(err) throw err;
  console.log("message sent");
});

输出：

server listening 0.0.0.0:1234
[ 'message', 'listening' ]
message sent
UDP String: Hello

使用以下命令运行 index.js 文件：

node index.js

参考： https ://nodejs.org/dist/latest-v12.x/docs/api/dgram.html#dgram_socket_send_msg_offset_length_port_address_callback