Send HTTP POST/GET request using HttpURLConnection in java

HttpURLConnectionExample.java

package com.hprog99;
 
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
 
import javax.net.ssl.HttpsURLConnection;
 
public class HttpURLConnectionExample {
 
	private final String USER_AGENT = "Mozilla/5.0";
 
	public static void main(String[] args) throws Exception {
 
		HttpURLConnectionExample http = new HttpURLConnectionExample();
 
		System.out.println("GET Request Using HttpURLConnection");
		http.sendGet();
                System.out.println();
		System.out.println("POST Request Using HttpURLConnection");
		http.sendPost();
 
	}
 
	// HTTP GET request
	private void sendGet() throws Exception {
	    
	    String username="hitenpratap";
        StringBuilder stringBuilder = new StringBuilder("https://twitter.com/search");
        stringBuilder.append("?q=");
        stringBuilder.append(URLEncoder.encode(username, "UTF-8"));
        
        URL obj = new URL(stringBuilder.toString());
 
		HttpURLConnection con = (HttpURLConnection) obj.openConnection();
		con.setRequestMethod("GET");
		con.setRequestProperty("User-Agent", USER_AGENT);
		connection.setRequestProperty("Accept-Charset", "UTF-8");
 
		System.out.println("\nSending request to URL : " + url);
		System.out.println("Response Code : " + con.getResponseCode());
		System.out.println("Response Message : " + con.getResponseMessage());
 
		BufferedReader in = new BufferedReader(
		        new InputStreamReader(con.getInputStream()));
		String line;
		StringBuffer response = new StringBuffer();
 
		while ((line = in.readLine()) != null) {
			response.append(line);
		}
		in.close();
 
		System.out.println(response.toString());
 
	}
 
	private void sendPost() throws Exception {
	    
	    StringBuilder tokenUri=new StringBuilder("param1=");
        tokenUri.append(URLEncoder.encode("params1","UTF-8"));
        tokenUri.append("&param2=");
        tokenUri.append(URLEncoder.encode("param2","UTF-8"));
        tokenUri.append("&param3=");
        tokenUri.append(URLEncoder.encode("param3","UTF-8"));
 
		String url = "https://example.com";
		URL obj = new URL(url);
		HttpsURLConnection con = (HttpsURLConnection) obj.openConnection();
 
		con.setRequestMethod("POST");
		con.setRequestProperty("User-Agent", USER_AGENT);
		con.setRequestProperty("Accept-Language", "UTF-8");
 
		con.setDoOutput(true);
		OutputStreamWriter outputStreamWriter = new OutputStreamWriter(con.getOutputStream());
        outputStreamWriter.write(params.toString());
        outputStreamWriter.flush();
 
		int responseCode = con.getResponseCode();
		System.out.println("\nSending 'POST' request to URL : " + url);
		System.out.println("Post parameters : " + urlParameters);
		System.out.println("Response Code : " + responseCode);
 
		BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
		String inputLine;
		StringBuffer response = new StringBuffer();
 
		while ((inputLine = in.readLine()) != null) {
			response.append(inputLine);
		}
		in.close();
 
		System.out.println(response.toString());
 
	}
 
}

Thanks for this. I was able to do my first Java send post with this :D I've added some suggestion to the comment.

Line 79: params does not exist.
Line 84: urlParameters does not exist.

With the tokenUri it's easier to read if was like this:
StringBuilder tokenUri=new StringBuilder("param1=");
tokenUri.append(URLEncoder.encode("value1","UTF-8"));
tokenUri.append("&param2=");
tokenUri.append(URLEncoder.encode("value2","UTF-8"));
tokenUri.append("&param3=");
tokenUri.append(URLEncoder.encode("value3","UTF-8"));

Cheers

Thank you it really helped

on line 40 connection.setRequestProperty("Accept-Charset", "UTF-8");
in this line you use "connection" where is it define in code or is it a java class, if it is java class so how i get its scope?

how to open another page?????

I am unable to send the parameters still through the post request even thought i used URLencoder

any help ??

This code worked for me

            URL url = new URL("https://ai.web.com/nov/index.php");
	Map<String,Object> params = new LinkedHashMap<>();
	params.put("accessid", "asasasasas");
	params.put("uid", "sasasasa");
	params.put("uname", "asasaa");
	params.put("agent", "sasasasasaddd");
	params.put("query", "adewewewe");
            StringBuilder postData = new StringBuilder();
	for (Map.Entry<String,Object> param : params.entrySet()) {
		if (postData.length() != 0) postData.append('&');
		postData.append(URLEncoder.encode(param.getKey(), "UTF-8"));
		postData.append('=');
		postData.append(URLEncoder.encode(String.valueOf(param.getValue()), "UTF-8"));
	}
	byte[] postDataBytes = postData.toString().getBytes("UTF-8");
	HttpURLConnection conn = (HttpURLConnection)url.openConnection();
	conn.setRequestMethod("POST");
	conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
	conn.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length));
	conn.setDoOutput(true);
	conn.getOutputStream().write(postDataBytes);
	Reader in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
	StringBuilder data = new StringBuilder();
	for (int c; (c = in.read()) >= 0;) {
		data.append((char)c);
	}
	String intentData = data.toString();
	System.out.println(intentData);	

I was able to post the post, but I can not read the json return in php

connect to URL

// connecting to URL
public void connectToUrl(){
 doTrustToCertificates();//  
 URL url = new URL("https://www.example.com");
 HttpURLConnection conn = (HttpURLConnection)url.openConnection(); 
 System.out.println("ResponseCode ="+conn.getResponseCode());

}