The HttpURLConnection
class from java.net
package can be used to send a Java HTTP Request programmatically. In this article, you will learn how to use HttpURLConnection
in a Java program to send GET
and POST
requests and then print the response.
For this HttpURLConnection
example, you should have completed the Spring MVC Tutorial because it has URLs for GET
and POST
HTTP methods.
Consider deploying to a localhost
Tomcat server.
Java HTTP GET Request
localhost:8080/SpringMVCExample/
Java HTTP GET Request for Login Page
localhost:8080/SpringMVCExample/login
Java HTTP POST Request
localhost:8080/SpringMVCExample?userName=Pankaj
localhost:8080/SpringMVCExample/login?userName=Pankaj&pwd=apple123
- for multiple paramsThe HTML of the login page contains the following form:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "https://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Login Page</title>
</head>
<body>
<form action="home" method="post">
<input type="text" name="userName"><br>
<input type="submit" value="Login">
</form>
</body>
</html>
method
is POST
.action
is home
.
localhost:8080/SpringMVCExample/home
userName
is of type text
.You can construct a POST
request to:
localhost:8080/SpringMVCExample/home?userName=Pankaj
This will serve as the basis for the HttpURLConnection
example.
HttpURLConnection
ExampleHere are the steps for sending Java HTTP requests using HttpURLConnection
class:
URL
object from the GET
or POST
URL String.openConnection()
method on the URL object that returns an instance of HttpURLConnection
.HttpURLConnection
instance (default value is GET
).setRequestProperty()
method on HttpURLConnection
instance to set request header values (such as "User-Agent"
, "Accept-Language"
, etc).getResponseCode()
to get the response HTTP code. This way, we know if the request was processed successfully or if there was any HTTP error message thrown.GET
, use Reader
and InputStream
to read the response and process it accordingly.POST
, before the code handles the response, it needs to get the OutputStream
from the HttpURLConnection
instance and write POST
parameters into it.Here is an example program that uses HttpURLConnection
to send Java GET
and POST
requests:
package com.journaldev.utils;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
public class HttpURLConnectionExample {
private static final String USER_AGENT = "Mozilla/5.0";
private static final String GET_URL = "https://localhost:9090/SpringMVCExample";
private static final String POST_URL = "https://localhost:9090/SpringMVCExample/home";
private static final String POST_PARAMS = "userName=Pankaj";
public static void main(String[] args) throws IOException {
sendGET();
System.out.println("GET DONE");
sendPOST();
System.out.println("POST DONE");
}
private static void sendGET() throws IOException {
URL obj = new URL(GET_URL);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
con.setRequestMethod("GET");
con.setRequestProperty("User-Agent", USER_AGENT);
int responseCode = con.getResponseCode();
System.out.println("GET Response Code :: " + responseCode);
if (responseCode == HttpURLConnection.HTTP_OK) { // success
BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
// print result
System.out.println(response.toString());
} else {
System.out.println("GET request did not work.");
}
}
private static void sendPOST() throws IOException {
URL obj = new URL(POST_URL);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
con.setRequestMethod("POST");
con.setRequestProperty("User-Agent", USER_AGENT);
// For POST only - START
con.setDoOutput(true);
OutputStream os = con.getOutputStream();
os.write(POST_PARAMS.getBytes());
os.flush();
os.close();
// For POST only - END
int responseCode = con.getResponseCode();
System.out.println("POST Response Code :: " + responseCode);
if (responseCode == HttpURLConnection.HTTP_OK) { //success
BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
// print result
System.out.println(response.toString());
} else {
System.out.println("POST request did not work.");
}
}
}
Compile and run the code. It will produce the following output:
OutputGET Response Code :: 200
<html><head> <title>Home</title></head><body><h1> Hello world! </h1><P> The time on the server is March 6, 2015 9:31:04 PM IST. </P></body></html>
GET DONE
POST Response Code :: 200
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "https://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>User Home Page</title></head><body><h3>Hi Pankaj</h3></body></html>
POST DONE
Compare this output to the browser HTTP response.
If you have to send GET
and POST
requests over HTTPS protocol, then you need to use javax.net.ssl.HttpsURLConnection
instead of java.net.HttpURLConnection
. HttpsURLConnection
will handle the SSL handshake and encryption.
In this article, you learned how to use HttpURLConnection
in a Java program to send GET
and POST
requests and then print the response.
Continue your learning with more Java tutorials.
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HttpURLConnection sets “connection: keep-alive” by default for every request. I have written a HTTP server and I am keeping the TCP connection open as request header contains keep-alive. But when sending second request, HttpURLConnection is opening new TCP connection. Shouldn’t it use first TCP connection itself. I have tried closing input stream and disconnecting HttpURLConnection instance, but still HttpURLConnection instance always opens a new TCP connection. I have even tried setting property “http.maxConnections” to “1”. Is there any way in android to send multiple HTTP requests on a single persistent TCP connection ?
- Harish
Hi Pankaj, thank you so much for the post. I have an issue. When i’m trying to do a POST, i do : HttpsURLConnection con = (HttpsURLConnection) obj.openConnection(); But when it try to do : OutputStream os = con.getOutputStream(); This happened: javax.net.ssl.SSLHandshakeException: Received fatal alert: handshake_failure Is weird because when i did a POST to a google service it worked well, but with other API has this exception. Thak you for your help.
- Julian
Hi Pankaj, I am trying to invoke a REST API. I am getting the proper response when invoked from POSTMAN. But, when I am trying to call from a Java program, I am getting the response in some junk characters. try { URL url = new URL(“https://ucf5-zodx-fa-ext.oracledemos.com/fscmRestApi/resources/11.13.18.05/erpintegrations”);//your url i.e fetch data from . SOAPHttpsURLConnection conn = (SOAPHttpsURLConnection) url.openConnection(); conn.setRequestMethod(“POST”); String authString = “fin_impl” + “:” + “…”; // masked the password for security reasons String encodedAuth = Base64.getEncoder().encodeToString(authString.getBytes()); String authHeader = “Basic " + encodedAuth; conn.setRequestProperty (“Authorization”, authHeader); conn.setRequestProperty(“Content-Type”,“application/json”); conn.setRequestProperty(“Accept”,“application/json”); conn.setRequestProperty(“Accept-Encoding”,“gzip”); conn.setConnectTimeout(5000); conn.setDoOutput(true); OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream()); String output = “{ “; output = output + “\””+“OperationName”+”\”:" + “\”" + “importBulkData” + “\”,“; output = output + “\””+“DocumentContent”+“\”:" + “\”" + “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” + “\”,“; output = output + “\””+“ContentType”+“\”:" + “\”" + “zip” + “\”,“; output = output + “\””+“FileName”+“\”:" + “\”" + “apinvoiceimport.zip” + “\”,“; output = output + “\””+“JobName”+“\”:" + “\”" + “oracle/apps/ess/financials/payables/invoices/transactions,APXIIMPT” + “\”,“; output = output + “\””+“ParameterList”+“\”:" + “\”" + “#NULL,US1 Business Unit,#NULL,#NULL,#NULL,#NULL,#NULL,External,#NULL,#NULL,#NULL,1,#NULL” + “\”“; output = output + " }”; System.out.println(“before writing… " + output); wr.write(output); wr.flush(); BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream(), “UTF-8”)); while ((responseLine = br.readLine()) != null) { System.out.println(”… "+ responseLine + " … "); response.append(responseLine); } conn.disconnect(); } catch (Exception e) { System.out.println("Exception in NetClientGet:- " + e); } I am getting some junk and non-printable characters in the response. something as below: … ? Please help. Thanks, Hari
- Lakshmi Hari
I am getting error while sending below: Response Code: 405 Response: {“Message”:“The requested resource does not support http method ‘POST’.”} My Code: URL obj = new URL(strWebServiceUrl); con = (HttpsURLConnection) obj.openConnection(); //add request header //con.setRequestMethod(“GET”); con.setRequestProperty(“Content-Type”, “text/plain”); con.setRequestProperty(strHeaderKey, strHeaderValue); con.setDoOutput(true); os = con.getOutputStream(); os.flush(); int responseCode = con.getResponseCode(); if(responseCode!=200) { in = new BufferedReader( new InputStreamReader(con.getErrorStream())); } else { in = new BufferedReader( new InputStreamReader(con.getInputStream())); } String inputLine; StringBuffer response = new StringBuffer(); while ((inputLine = in.readLine()) != null) { response.append(inputLine); } if(responseCode!=200) { logger.error("Error Response Code from webservice is “+responseCode+” Response: “+response.toString()); System.out.println(response.toString()); } else { logger.info(” SUCCESSFUL response from web service: "+response.toString()); System.out.println(response.toString()); }
- Prem C
Hi , I am using Post method to send JSON object through proxy setting and header . Response I am getting 500 Internal server Error ? Please help me. Thx
- Paddy
How can i send a request body which contains nested Json for example using java.net.HttpURLConnection:- { “moduleId”: “abc”, “properties”: { “desired”: { “Graphs”: { “PersonDetection”: { “location”: “https://graphexample.yaml”, “version”: 1, “parameters”: {}, “enabled”: true, “status”: “started” } } } }
- Neha
Hello I have to send a GET request with parameter and get Json response from third party using API key. Kindly help.
- Ramya
here is my function below : , connection is made successfully because i receive response 200 but it send blank data to the POST request. hence my POST request makes entry to db with all fields blank except id i.e. which I am generating on POST request on server side. Note : when I capture the url and json string on debug mode , and send same through POSTMAN , data gets created successfully at DB and i receive 200. I am clueless now, how to debug the issue public static int POST(String urlstr, String jsonbody) { URL url = null; HttpURLConnection urlConnection = null; String result = “”; try { url = new URL(urlstr); urlConnection = (HttpURLConnection) url.openConnection(); urlConnection.setConnectTimeout(5000); urlConnection.setRequestProperty(“Content-Type”, “application/json”); urlConnection.setRequestProperty(“Accept”, “application/json”); urlConnection.setDoInput(true); urlConnection.setDoOutput(true); urlConnection.setRequestMethod(“POST”); OutputStream wr = urlConnection.getOutputStream(); wr.write(jsonbody.getBytes()); wr.flush(); wr.close(); System.out.println(“response code from server” + urlConnection.getResponseCode()); return urlConnection.getResponseCode(); } catch (Exception e) { e.printStackTrace(); return 500; }finally { urlConnection.disconnect(); } }
- seema
Hi Pankaj, I have one small required with this HTTP post connection, in postman I am using post method to pass a url and content from body section choosing raw option. I am able to open the connection but not sure how to post this body content in post call. can you please advise. Thanks in advance
- Teena
Hai I have to develop a program for get and post request can you help me for that.
- Krishnan