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Am writing a service using the HTTPServer provided by com.sun.net.httpserver.HttpServer package. I need to send some sizable data as a byte stream to this service (say a million integers).
I have almost searched all the examples available, all point to sending a small GET request in the URL.
I need to know how to send the data as a POST request.
Also is there any limit on the data that can be sent?
Rather than persistent URL connection in the answer above, I would recommend using Apache HTTPClient libraries (if you are not using Spring for applet-servlet communication)
http://hc.apache.org/httpclient-3.x/
In this you can build a client and send a serialized object (for instance serialised to JSON string: https://code.google.com/p/google-gson/ ) as POST request over HTTP to your server:
public HttpResponse sendStuff (args) {
HttpPost post = null;
try {
HttpClient client = HttpClientBuilder.create().build();
post = new HttpPost(servletUrl);
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair(<nameString>, <valueString>));
post.setEntity(new UrlEncodedFormEntity(params));
HttpResponse response = client.execute(post);
response.getStatusLine().getStatusCode();
return response;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
However Spring saves you a lot of time and hassle so I would recommend to check it out
You can send the data for the POST request by writing bytes to the connections output stream as shown below
public static String excutePost(String targetURL, String urlParameters)
{
URL url;
HttpURLConnection connection = null;
try {
//Create connection
url = new URL(targetURL);
connection = (HttpURLConnection)url.openConnection();
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type",
"application/x-www-form-urlencoded");
connection.setRequestProperty("Content-Length", "" +
Integer.toString(urlParameters.getBytes().length));
connection.setRequestProperty("Content-Language", "en-US");
connection.setUseCaches (false);
connection.setDoInput(true);
connection.setDoOutput(true);
//Send request
DataOutputStream wr = new DataOutputStream (
connection.getOutputStream ());
wr.writeBytes (urlParameters);
wr.flush ();
wr.close ();
//Get Response
InputStream is = connection.getInputStream();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
String line;
StringBuffer response = new StringBuffer();
while((line = rd.readLine()) != null) {
response.append(line);
response.append('\r');
}
rd.close();
return response.toString();
} catch (Exception e) {
e.printStackTrace();
return null;
} finally {
if(connection != null) {
connection.disconnect();
}
}
}
With POST, there is no limit on the amount of data that can be sent. You can find out the details about the limitations of GET here maximum length of HTTP GET request?
If I got you right, you want to send requests in direction of your HTTPServer, as a GET request instead of using post.
In your HTTP Client implementation you can set the HTTP Headers and also the request Method:
HttpURLConnection connection = null;
try {
connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("GET"); //Or POST
} catch (IOException e) {
e.printStacktrace();
}
Related
I'm currently working on a project using an IoT platform " Thingsboard " where I've have created multiple devices, and I want to send data to each one of the devices from a JSON File, I'm using Rest Api to perform this request, but I've struggling for a while how to get the access token of my devices and parse each one of them in my request as a header param. I was just doing manually by getting them with Curl, but I want now to do it automatically. I know that Thingsboard has a Rest client Api written in java (https://thingsboard.io/docs/reference/rest-client/) so I've tried to use that in my script but I's not working. I'm new to working with Rest Api so if anybody can gie me a clue it would be so helpful.
here's a part of my code for the requests :
private static String token;
public String getToken() {
return token;
}
String paramValue = "param\\with\\backslash";
String yourURLStr = "http://host.com?param=" + java.net.URLEncoder.encode(paramValue, "UTF-8");
URL url2 = new URL("https://demo.thingsboard.io/api/v1/token/telemetry?token=$JWT_TOKEN");
HttpsURLConnection conn = (HttpsURLConnection) url2.openConnection();
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/json");
conn.setRequestProperty("Accept", "application/json");
conn.setRequestProperty(JWT_TOKEN_HEADER_PARAM, "Bearer" +token);
conn.setDoOutput(true);
OutputStream outStream = conn.getOutputStream();
OutputStreamWriter outStreamWriter = new OutputStreamWriter(outStream, "UTF-8");
outStreamWriter.write(list.toString());
outStreamWriter.flush();
outStreamWriter.close();
outStream.close();
String response = null;
System.out.println(conn.getResponseCode());
System.out.println(conn.getResponseMessage());
DataInputStream input1 = null;
input1 = new DataInputStream (conn.getInputStream());
while (null != ((response = input1.readLine()))) {
System.out.println(response);
input1.close ();
}
}
catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ParseException e) {
e.printStackTrace();
}
If you are trying to get the JWT-token to authenticate the following java should work:
Request request = Request.Post("http://THINGSBOARD_URL/api/auth/login");
String body = "{\"username\":\"tenant#thingsboard.org\", \"password\":\"tenant\"}";
request.bodyString(body,ContentType.APPLICATION_JSON);
request.setHeader("Content-Type", "application/json");
request.setHeader("Accept", "application/json");
HttpResponse httpResponse = request.execute().returnResponse();
System.out.println(httpResponse.getStatusLine());
if (httpResponse.getEntity() != null) {
String html = EntityUtils.toString(httpResponse.getEntity());
System.out.println(html);
}
Don't get confused with JWT-Token for tenant authentication and Access-Token for Device Authentication.
This question already has answers here:
Sending HTTP POST Request In Java
(12 answers)
Closed 4 years ago.
I am completely lost on how to send a POST request in Java. I understand how to do in Python with the request module, but no luck with Java. So, I was wondering if anyone could give me a clear example of how this is done via logging into a webpage such as instagram.com. I appreciate all responses. Thanks in advance.
if you do not want to use extra library，you can try HttpURLConnection:
public static String doPost(String url, String postData) {
PrintWriter out = null;
BufferedReader in = null;
String result = "";
try {
URL realUrl = new URL(url);
// build connection
URLConnection conn = realUrl.openConnection();
// set request properties
conn.setRequestProperty("accept", "*/*");
conn.setRequestProperty("connection", "Keep-Alive");
conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");
// enable output and input
conn.setDoOutput(true);
conn.setDoInput(true);
out = new PrintWriter(conn.getOutputStream());
// send POST DATA
out.print(postData);
out.flush();
in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String line;
while ((line = in.readLine()) != null) {
result += "/n" + line;
}
} catch (Exception e) {
e.printStackTrace();
}
finally {
try {
if (out != null) {
out.close();
}
if (in != null) {
in.close();
}
} catch (IOException ex) {
ex.printStackTrace();
}
}
return result;
}
You can use Spring Web RestTemplate:
new RestTemplate().postForObject(url, requestObject, responseType);
you can use OkHttp
https://github.com/square/okhttp
public static final MediaType JSON
= MediaType.parse("application/json; charset=utf-8");
OkHttpClient client = new OkHttpClient();
String post(String url, String json) throws IOException {
RequestBody body = RequestBody.create(JSON, json);
Request request = new Request.Builder()
.url(url)
.post(body)
.build();
Response response = client.newCall(request).execute();
return response.body().string();
}
I use a simple WebServer from http://www.java2s.com/Code/Java/Network-Protocol/AverysimpleWebserverWhenitreceivesaHTTPrequestitsendstherequestbackasthereply.htm
and Android code from Sending json object via http post method in android
In my main Activity:
AsyncT asyncT = new AsyncT();
asyncT.execute();
Class:
class AsyncT extends AsyncTask<Void,Void,Void>{
#Override
protected Void doInBackground(Void... params) {
try {
URL url = new URL(""); //Enter URL here
HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
httpURLConnection.setDoOutput(true);
httpURLConnection.setRequestMethod("POST"); // here you are telling that it is a POST request, which can be changed into "PUT", "GET", "DELETE" etc.
httpURLConnection.setRequestProperty("Content-Type", "application/json"); // here you are setting the `Content-Type` for the data you are sending which is `application/json`
httpURLConnection.connect();
JSONObject jsonObject = new JSONObject();
jsonObject.put("para_1", "arg_1");
DataOutputStream wr = new DataOutputStream(httpURLConnection.getOutputStream());
wr.writeBytes(jsonObject.toString());
wr.flush();
wr.close();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
}
The connection is established without any errors ("HostConnection::get() New Host Connection established"). However, I am not able to get in my Java server any information from the request. When I read from input stream
BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
System.out.println(in);
I get java.io.BufferedReader#4d7hge12
And this outputs nothing:
String line;
while ((line = in.readLine()) != null) {
if (line.length() == 0)
break;
System.out.println(line);
}
Don't re-invent the wheel and use a library for this.
For example okhttp:
public static final MediaType JSON = MediaType.parse("application/json; charset=utf-8");
OkHttpClient client = new OkHttpClient();
String post(String url, String json) throws IOException {
RequestBody body = RequestBody.create(JSON, json);
Request request = new Request.Builder()
.url(url)
.post(body)
.build();
Response response = client.newCall(request).execute();
return response.body().string();
}
If you want to call a REST-API you can use retrofit (which is build ontop of okhttp)
Assuming you're doing this as a learning exercise, so using another library isn't what you're looking for, I would suggest a couple of things:
(1) install Wireshark and see what the actual response coming back the server is, does it look sensible?
(2) break that line of code out into separate lines, is the InputStream / InputStreamReader null?
How come I am only allowed to make posts to .com url's but not .asmx url's? Im a bit confused as what I want to generally do is send xml content to a .asmx url web service eventually. Can anyone supply me with tips why this doesn't work, and how I can post to a .asmx file?
public class POSTSenderExample {
public String echoCuties(String query) throws IOException {
// Encode the query
String encodedQuery = URLEncoder.encode(query, "UTF-8");
// This is the data that is going to be send to itcuties.com via POST request
// 'e' parameter contains data to echo
String postData = "e=" + encodedQuery;
URL url = new URL("http://echo.itgeeeks.asmx");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
connection.setRequestProperty("Content-Length", String.valueOf(postData.length()));
// Write data
OutputStream os = connection.getOutputStream();
os.write(postData.getBytes());
// Read response
StringBuilder responseSB = new StringBuilder();
BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String line;
while ( (line = br.readLine()) != null)
responseSB.append(line);
// Close streams
br.close();
os.close();
return responseSB.toString();
}
// Run this example
public static void main(String[] args) {
try {
System.out.println(new POSTSenderExample().echoCuties("Hi there!"));
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
}
Using "POST" is correct.
Instead of calling
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
you have to call
connection.setRequestProperty("Content-Type", "text/xml; charset=utf-8");
(if you are using utf-8 encoding which is probably the case).
You also have to set the SOAP Action in the http- Header:
connection.setRequestProperty("SOAPAction", SOAPAction);
You can find the SOAP Action eihter in the wsdl- file. What I did to find out all expected Parameters: I used a working WS Client, and traced the TCP traffic in order to find out the expected HTTP headers.
Why does this not work? I have also tried using HttpURLConnection class however this did not work either. The php page cannot find the posted data.
Note: im new to post requests with java.
public static String GetURL(String inUrl, String post) {
String inputLine = "";
try {
if (!inUrl.contains("http")) {
throw new Exception("Invalid URL");
} else {
Log.writeLog(inUrl);
URL url = new URL(inUrl);
//send post
URLConnection connection = url.openConnection();
//connection.setRequestMethod("POST");
connection.setDoOutput(true);
connection.setRequestProperty("Accept-Charset", "UTF-8");
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded;charset=UTF-8");
connection.connect();
OutputStream wr = connection.getOutputStream();
wr.write(post.getBytes());
wr.flush();
wr.close();
BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
inputLine = in.readLine();
in.close();
}
} catch (Exception ex) {
ex.printStackTrace();
Log.writeLog("Error getting url.");
}
return inputLine;
}
Since you didn't specify the error, it is hard for me to see where you went wrong.
However, I think it would be a lot easier to use an abstraction like HttpClient. Your code would look like this:
URI uri = new URIBuilder()
.setURI(inUrl)
.addHeader("Accept-Charset", "UTF-8")
.addHeader("Content-Type", "application/x-www-form-urlencoded")
.build();
HttpPost httpPost = new HttpPost(uri);
httpPost.setEntity(post);
Much cleaner than dealing with the low-level details of streams and connections.