How to send WhatsApp Messages in Java

This article shows you how to send a WhatsApp message in Java.

Before the recipient can receive your WhatsApp message, she will need to register with the WhatsMate WA Gateway. Instructions are available on the official site. Unregistered users will never receive messages from the Gateway.

To send a WhatsApp message in Java, do this:

1. Copy the following source code to a Java file named WhatsappSender.java.

   	import java.io.BufferedReader;
   	import java.io.OutputStream;
   	import java.io.InputStreamReader;
   	import java.net.HttpURLConnection;
   	import java.net.URL;
   	public class WhatsappSender {
   	// TODO: Replace the following with your instance ID, Forever Green Client ID and Secret:
   	private static final String INSTANCE_ID = "YOUR_INSTANCE_ID_HERE";
   	private static final String CLIENT_ID = "YOUR_CLIENT_ID_HERE";
   	private static final String CLIENT_SECRET = "YOUR_CLIENT_SECRET_HERE";
   	private static final String WA_GATEWAY_URL = "http://api.whatsmate.net/v3/whatsapp/single/text/message/" + INSTANCE_ID;
   	/**
   	* Entry Point
   	*/
   	public static void main(String[] args) throws Exception {
   	String number = "12025550108"; // TODO: Specify the recipient's number here. NOT the gateway number
   	String message = "Howdy, isn't this exciting?"; // For multi-line messages, use "Line one \\n line two"
   	WhatsappSender.sendMessage(number, message);
   	}
   	/**
   	* Sends out a WhatsApp message via WhatsMate WA Gateway.
   	*/
   	public static void sendMessage(String number, String message) throws Exception {
   	// TODO: Should have used a 3rd party library to make a JSON string from an object
   	String jsonPayload = new StringBuilder()
   	.append("{")
   	.append("\"number\":\"")
   	.append(number)
   	.append("\",")
   	.append("\"message\":\"")
   	.append(message)
   	.append("\"")
   	.append("}")
   	.toString();
   	URL url = new URL(WA_GATEWAY_URL);
   	HttpURLConnection conn = (HttpURLConnection) url.openConnection();
   	conn.setDoOutput(true);
   	conn.setRequestMethod("POST");
   	conn.setRequestProperty("X-WM-CLIENT-ID", CLIENT_ID);
   	conn.setRequestProperty("X-WM-CLIENT-SECRET", CLIENT_SECRET);
   	conn.setRequestProperty("Content-Type", "application/json");
   	OutputStream os = conn.getOutputStream();
   	os.write(jsonPayload.getBytes());
   	os.flush();
   	os.close();
   	int statusCode = conn.getResponseCode();
   	System.out.println("Response from WA Gateway: \n");
   	System.out.println("Status Code: " + statusCode);
   	BufferedReader br = new BufferedReader(new InputStreamReader(
   	(statusCode == 200) ? conn.getInputStream() : conn.getErrorStream()
   	));
   	String output;
   	while ((output = br.readLine()) != null) {
   	System.out.println(output);
   	}
   	conn.disconnect();
   	}
   	}

   view raw WhatsappSender.java hosted with ❤ by GitHub
2. Customize the TODO lines:
   • Specify your gateway instance ID on line 9.
   • Specify your client ID and secret on lines 10 and 11.
   • Specify your target recipient on line 18. Remember to include the country code.
   • Specify your message on line 19.
3. Compile the Java file: javac WhatsappSender.java
4. Execute the class to send your message: java WhatsappSender

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