I would like to make a simple HTTP POST using JSON in Java.
Let's say the URL is www.site.com
and it takes in the value {"name":"myname","age":"20"} labeled as 'details' for example.
How would I go about creating the syntax for the POST?
I also can't seem to find a POST method in the JSON Javadocs.
Here is what you need to do:
Get the Apache HttpClient, this would enable you to make the required request
Create an HttpPost request with it and add the header application/x-www-form-urlencoded
Create a StringEntity that you will pass JSON to it
Execute the call
The code roughly looks like (you will still need to debug it and make it work):
// #Deprecated HttpClient httpClient = new DefaultHttpClient();
HttpClient httpClient = HttpClientBuilder.create().build();
try {
HttpPost request = new HttpPost("http://yoururl");
StringEntity params = new StringEntity("details={\"name\":\"xyz\",\"age\":\"20\"} ");
request.addHeader("content-type", "application/x-www-form-urlencoded");
request.setEntity(params);
HttpResponse response = httpClient.execute(request);
} catch (Exception ex) {
} finally {
// #Deprecated httpClient.getConnectionManager().shutdown();
}
You can make use of Gson library to convert your java classes to JSON objects.
Create a pojo class for variables you want to send
as per above Example
{"name":"myname","age":"20"}
becomes
class pojo1
{
String name;
String age;
//generate setter and getters
}
once you set the variables in pojo1 class you can send that using the following code
String postUrl = "www.site.com";// put in your url
Gson gson = new Gson();
HttpClient httpClient = HttpClientBuilder.create().build();
HttpPost post = new HttpPost(postUrl);
StringEntity postingString = new StringEntity(gson.toJson(pojo1));//gson.tojson() converts your pojo to json
post.setEntity(postingString);
post.setHeader("Content-type", "application/json");
HttpResponse response = httpClient.execute(post);
and these are the imports
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.HttpClientBuilder;
and for GSON
import com.google.gson.Gson;
#momo's answer for Apache HttpClient, version 4.3.1 or later. I'm using JSON-Java to build my JSON object:
JSONObject json = new JSONObject();
json.put("someKey", "someValue");
CloseableHttpClient httpClient = HttpClientBuilder.create().build();
try {
HttpPost request = new HttpPost("http://yoururl");
StringEntity params = new StringEntity(json.toString());
request.addHeader("content-type", "application/json");
request.setEntity(params);
httpClient.execute(request);
// handle response here...
} catch (Exception ex) {
// handle exception here
} finally {
httpClient.close();
}
It's probably easiest to use HttpURLConnection.
http://www.xyzws.com/Javafaq/how-to-use-httpurlconnection-post-data-to-web-server/139
You'll use JSONObject or whatever to construct your JSON, but not to handle the network; you need to serialize it and then pass it to an HttpURLConnection to POST.
protected void sendJson(final String play, final String prop) {
Thread t = new Thread() {
public void run() {
Looper.prepare(); //For Preparing Message Pool for the childThread
HttpClient client = new DefaultHttpClient();
HttpConnectionParams.setConnectionTimeout(client.getParams(), 1000); //Timeout Limit
HttpResponse response;
JSONObject json = new JSONObject();
try {
HttpPost post = new HttpPost("http://192.168.0.44:80");
json.put("play", play);
json.put("Properties", prop);
StringEntity se = new StringEntity(json.toString());
se.setContentType(new BasicHeader(HTTP.CONTENT_TYPE, "application/json"));
post.setEntity(se);
response = client.execute(post);
/*Checking response */
if (response != null) {
InputStream in = response.getEntity().getContent(); //Get the data in the entity
}
} catch (Exception e) {
e.printStackTrace();
showMessage("Error", "Cannot Estabilish Connection");
}
Looper.loop(); //Loop in the message queue
}
};
t.start();
}
Try this code:
HttpClient httpClient = new DefaultHttpClient();
try {
HttpPost request = new HttpPost("http://yoururl");
StringEntity params =new StringEntity("details={\"name\":\"myname\",\"age\":\"20\"} ");
request.addHeader("content-type", "application/json");
request.addHeader("Accept","application/json");
request.setEntity(params);
HttpResponse response = httpClient.execute(request);
// handle response here...
}catch (Exception ex) {
// handle exception here
} finally {
httpClient.getConnectionManager().shutdown();
}
I found this question looking for solution about how to send post request from java client to Google Endpoints. Above answers, very likely correct, but not work in case of Google Endpoints.
Solution for Google Endpoints.
Request body must contains only JSON string, not name=value pair.
Content type header must be set to "application/json".
post("http://localhost:8888/_ah/api/langapi/v1/createLanguage",
"{\"language\":\"russian\", \"description\":\"dsfsdfsdfsdfsd\"}");
public static void post(String url, String json ) throws Exception{
String charset = "UTF-8";
URLConnection connection = new URL(url).openConnection();
connection.setDoOutput(true); // Triggers POST.
connection.setRequestProperty("Accept-Charset", charset);
connection.setRequestProperty("Content-Type", "application/json;charset=" + charset);
try (OutputStream output = connection.getOutputStream()) {
output.write(json.getBytes(charset));
}
InputStream response = connection.getInputStream();
}
It sure can be done using HttpClient as well.
You can use the following code with Apache HTTP:
String payload = "{\"name\": \"myname\", \"age\": \"20\"}";
post.setEntity(new StringEntity(payload, ContentType.APPLICATION_JSON));
response = client.execute(request);
Additionally you can create a json object and put in fields into the object like this
HttpPost post = new HttpPost(URL);
JSONObject payload = new JSONObject();
payload.put("name", "myName");
payload.put("age", "20");
post.setEntity(new StringEntity(payload.toString(), ContentType.APPLICATION_JSON));
For Java 11 you can use the new HTTP client:
HttpClient client = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder()
.uri(URI.create("http://localhost/api"))
.header("Content-Type", "application/json")
.POST(ofInputStream(() -> getClass().getResourceAsStream(
"/some-data.json")))
.build();
client.sendAsync(request, BodyHandlers.ofString())
.thenApply(HttpResponse::body)
.thenAccept(System.out::println)
.join();
You can use publishers from InputStream, String, File. Converting JSON to a String or IS can be done with Jackson.
Java 11 standardization of HTTP client API that implements HTTP/2 and Web Socket, and can be found at java.net.HTTP.*:
String payload = "{\"name\": \"myname\", \"age\": \"20\"}";
HttpClient client = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder(URI.create("www.site.com"))
.header("content-type", "application/json")
.POST(HttpRequest.BodyPublishers.ofString(payload))
.build();
HttpResponse<String> response = client.send(request, BodyHandlers.ofString());
Java 8 with apache httpClient 4
CloseableHttpClient client = HttpClientBuilder.create().build();
HttpPost httpPost = new HttpPost("www.site.com");
String json = "details={\"name\":\"myname\",\"age\":\"20\"} ";
try {
StringEntity entity = new StringEntity(json);
httpPost.setEntity(entity);
// set your POST request headers to accept json contents
httpPost.setHeader("Accept", "application/json");
httpPost.setHeader("Content-type", "application/json");
try {
// your closeablehttp response
CloseableHttpResponse response = client.execute(httpPost);
// print your status code from the response
System.out.println(response.getStatusLine().getStatusCode());
// take the response body as a json formatted string
String responseJSON = EntityUtils.toString(response.getEntity());
// convert/parse the json formatted string to a json object
JSONObject jobj = new JSONObject(responseJSON);
//print your response body that formatted into json
System.out.println(jobj);
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
I recomend http-request built on apache http api.
HttpRequest<String> httpRequest = HttpRequestBuilder.createPost(yourUri, String.class)
.responseDeserializer(ResponseDeserializer.ignorableDeserializer()).build();
public void send(){
ResponseHandler<String> responseHandler = httpRequest.execute("details", yourJsonData);
int statusCode = responseHandler.getStatusCode();
String responseContent = responseHandler.orElse(null); // returns Content from response. If content isn't present returns null.
}
If you want send JSON as request body you can:
ResponseHandler<String> responseHandler = httpRequest.executeWithBody(yourJsonData);
I higly recomend read documentation before use.
I am trying to create a simple post request to a web API and parse the response received. After quite a lot of search, I was able to come up with the following code:
public class access {
public static void main(String[] args) {
HttpClient httpclient = HttpClients.createDefault();
HttpPost httppost = new HttpPost("https://xxxxx/RSAM_API/api/Logon");
httppost.setHeader("Accept", "application/json");
httppost.setHeader("Content-type", "application/json");
// Request parameters and other properties.
List<NameValuePair> urlParameters = new ArrayList<NameValuePair>(2);
urlParameters.add(new BasicNameValuePair("UserId", "xxxxxx"));
urlParameters.add(new BasicNameValuePair("Password", "xxxxxxx"));
try {
httppost.setEntity(new UrlEncodedFormEntity(urlParameters));
//Execute and get the response.
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
BufferedReader rd = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
String line;
while(null !=(line=rd.readLine())){
System.out.println(line);
}
}
catch (Exception e){
e.printStackTrace();
}
}
}
In the above code, I am doing an post request to the URL login endpoint. the response I see after parsing it is:
An error occurred, please try again or contact the administrator with this error id, 26225
I am able to login to the URL through the browser manually. Not sure where I am going wrong in the code.
Is my approach correct in the first place? Can I be sure that my code is right? If it is, why is the response an error?
Any help would be appreciated. Thank you.
I have a dropwizard service in whitch i implemented a post request who consumes APPLICATION_FORM_URLENCODED media type and uses #FormParam annotation
Then in my client i'm using Apache HttpClient to make a post request like this:
public void sendPost(String path, JsonObject params) throws Exception {
String url = "http://" + TS_API_HOST + ":" + TS_API_PORT + "/" + path;
CloseableHttpClient httpClient = HttpClients.createDefault();
HttpPost httpPost = new HttpPost(url);
httpPost.setHeader("Content-Type", "application/x-www-form-urlencoded");
List<NameValuePair> nvps = new ArrayList<NameValuePair>();
Iterator<String> keys = params.keySet().iterator();
while(keys.hasNext()){
String currentKey = keys.next();
nvps.add(new BasicNameValuePair(currentKey, params.get(currentKey).toString()));
}
System.out.println(nvps.toString());
httpPost.setEntity(new UrlEncodedFormEntity(nvps));
CloseableHttpResponse response = httpClient.execute(httpPost);
try {
System.out.println(response.getStatusLine());
HttpEntity entity2 = response.getEntity();
// do something useful with the response body
// and ensure it is fully consumed
EntityUtils.consume(entity2);
} finally {
response.close();
}
}
The url and params I'm passing are correct but i keep getting 400 bad request as a response.
In Postman it works very well...
I'm sending parameters from my android app to the backend and trying to retrieve the parameters sent by my android clients in my POST Method but I keep getting null parameters even though the clients are sending parameters which are not null.
Java POST Method:
#POST
#Produces({ "application/json" })
#Path("/login")
public LoginResponse Login(#FormParam("email") String email, #FormParam("password") String password) {
LoginResponse response = new LoginResponse();
if(email != null && password != null && email.length() != 0 && password.length() != 0){
//Detect if null or empty
//Code
}
return response;
}
Android Client:
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://MY_APP_NAME.appspot.com/user/login");
String json = "";
JSONObject jsonObject = new JSONObject();
try {
jsonObject.accumulate("email", "roger#gmail.com");
jsonObject.accumulate("password", "123");
json = jsonObject.toString();
StringEntity se = new StringEntity(json);
httppost.setEntity(se);
httppost.setHeader("Content-Type", "application/json");
httppost.setHeader("ACCEPT", "application/json");
HttpResponse httpResponse = httpclient.execute(httppost);
}
catch(Exception ex) { }
I believe the Content-Type of the method and the client is the same as well. Why am I not receiving the parameters from the Java Backend Method?
CHECKED:
The URL is correct and the connection is working
The Parameters sent by the app are not null
We hope i got you, try NameValuePair
public void postData() {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://www.yoursite.com/yourscript.php");
try {
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
nameValuePairs.add(new BasicNameValuePair("id", "123"));
nameValuePairs.add(new BasicNameValuePair("string", "Hey"));
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
// Execute HTTP Post Request
HttpResponse response = httpclient.execute(httppost);
} catch (ClientProtocolException e) {
// Catch Protocol Exception
} catch (IOException e) {
// Catch IOException
}
}
Just in case you have similar problems, I'd suggest using Fiddler
which is a free http inspector and debugger by which you can see the http request your app is sending to the backend server and the backend answer.
Best of luck
Please forgive me if I ask something stupid, I am a novice here. I need to implement OAuth in my Java application to authenticate against launchpad.net API. The documentation specifies an initiation of a token request with three parameters : oauth_consumer_key e.g. (name of my application), oauth_signature_method e.g. "PLAINTEXT" and oauth_signature e.g. The string "&". I realised that most OAuth libraries require that
I have already acquired a Consumer key and Consumer Id/Secret from
the OAuth provider (e.g as issued in Twitter), and most examples are organised in this manner. However, launchpad.net will issue these parameters only after issuance of request token (they use no third party provider). How can I proceed?I am currently stuck after trying some libraries that threw errors. Many thanks for any useful information. The official launchpad library is in python.
My initial code is below:
public class Quicky {
public static void main(String[] args) throws Exception {
CloseableHttpClient httpclient = HttpClients.createDefault();
try {
HttpGet httpGet = new HttpGet("https://launchpad.net/+request-token");
CloseableHttpResponse response1 = httpclient.execute(httpGet);
try {
System.out.println("Your current GET request status:" + response1.getStatusLine());
HttpEntity entity1 = response1.getEntity();
EntityUtils.consume(entity1);
} finally {
response1.close();
}
HttpRequest request;
HttpPost httpPost = new HttpPost("https://launchpad.net/+request-token");
PostMethod poster = new PostMethod();
List <NameValuePair> postParams = new ArrayList <NameValuePair>();
postParams.add(new BasicNameValuePair("oauth_customer_key", "XXXX"));
postParams.add(new BasicNameValuePair("oauth_signature_method", "PLAINTEXT"));
postParams.add(new BasicNameValuePair("oauth_signature", "&"));
httpPost.setEntity(new UrlEncodedFormEntity(postParams, "utf-8"));
// httpPost.setEntity(entity1);
httpclient.execute(httpPost);
HttpParameters requestParams = (HttpParameters) postParams;
CloseableHttpResponse response2 = httpclient.execute(httpPost);
try {
System.out.println("Your current POST request status:" + response2.getStatusLine());
HttpEntity entity2 = response2.getEntity();
// do something useful with the response body
// and ensure it is fully consumed
EntityUtils.consume(entity2);
} finally {
response2.close();
}
} finally {
httpclient.close();
}
}
}
I finally resolved the issue error messages after some research and code re-factoring. The correct code is below, maybe it could be useful to someone out there.
public class LaunchPadTokenRetriever {
public static void main(String[] args) throws ClientProtocolException, IOException{
CloseableHttpClient httpclient = HttpClients.createDefault();
HttpPost httpPost = new HttpPost("https://launchpad.net/+request-token");
httpPost.addHeader("Content-Type", "application/x-www-form-urlencoded");
List <NameValuePair> urlParams = new ArrayList <NameValuePair>();
urlParams.add(new BasicNameValuePair("oauth_signature", "&"));
urlParams.add(new BasicNameValuePair("oauth_consumer_key", "tester"));
urlParams.add(new BasicNameValuePair("oauth_signature_method", "PLAINTEXT"));
httpPost.setEntity(new UrlEncodedFormEntity(urlParams));
CloseableHttpResponse response = httpclient.execute(httpPost);
System.out.println(response);
try {
System.out.println(response.getStatusLine());
HttpEntity entity = response.getEntity();
ResponseHandler<String> responseHandler = new BasicResponseHandler();
String responseBody = httpclient.execute(httpPost, responseHandler);
System.out.println("Initial credentials ---> "+ responseBody);
System.out.println();
String getresponse = responseBody;
EntityUtils.consume(entity);
} finally {
response.close();
}
}
}