I am trying to use an API from https://us.mc-api.net/ for a project and I have made this as a test.
public static void main(String[] args){
try {
URL url = new URL("http://us.mc-api.net/v3/uuid/193nonaxishsl/csv/");
BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
String line;
while ((line = in.readLine()) != null) {
System.out.println(line);
}
in.close();
}
catch (MalformedURLException e) {
e.printStackTrace();
}
catch (IOException e) {
e.printStackTrace();
System.out.println("I/O Error");
}
}
}
And this is giving me an IOException error but when ever I open the same page in my web browser I get
false,Unknown-Username
which is what I want to get from the code. I am new and don't really know why it is happening or why.
EDIT: StackTrace
java.io.FileNotFoundException: http://us.mc-api.net/v3/uuid/193nonaxishsl/csv/
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
at java.net.URL.openStream(Unknown Source)
at com.theman1928.Test.Main.main(Main.java:13)
The URL is returning status code 404 and therefore the input stream (mild guess here) is not being created and therefore is null. Sort the status code and you should be OK.
Ran it with this CSV and it is fine: other csv
If the error code is important to you then you can use HttpURLConnection:
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
System.out.println("code:"+conn.getResponseCode());
In that way you can process the response code before proceeding with a quick if-then-else check.
I tried it with the Apache HTTP libraries. The API endpoint seems to return a status code of 404, hence your error. Code I used is below.
public static void main(String[] args) throws URISyntaxException, ClientProtocolException, IOException {
HttpClient httpclient = HttpClients.createDefault();
URIBuilder builder = new URIBuilder("http://us.mc-api.net/v3/uuid/193nonaxishsl/csv/");
URI uri = builder.build();
HttpGet request = new HttpGet(uri);
HttpResponse response = httpclient.execute(request);
System.out.println(response.getStatusLine().getStatusCode()); // 404
}
Switching out the http://us.mc-api.net/v3/uuid/193nonaxishsl/csv/ with www.example.com or whatever returns a status code of 200, which further proves an error with the API endpoint. You can take a look at [Apache HTTP Components] library here.
This has to do with how the wire protocols are working in comparison with the java.net classes and an actual browser. A browser is going to be much more sophisticated than the simple java.net API you are using.
If you want to get the equivalent response value in Java, then you need to use a richer HTTP API.
This code will give you the same response as the browser; however, you need to download the Apache HttpComponents jars
The code:
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import javax.net.ssl.HttpsURLConnection;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.impl.client.HttpClients;
public class TestDriver
{
public static void main(String[] args)
{
try
{
String url = "http://us.mc-api.net/v3/uuid/193nonaxishsl/csv";
HttpGet httpGet = new HttpGet(url);
getResponseFromHTTPReq(httpGet, url);
}
catch (Throwable e)
{
e.printStackTrace();
}
}
private static String getResponseFromHTTPReq(HttpUriRequest httpReq, String url)
{
HttpClient httpclient = HttpClients.createDefault();
// Execute and get the response.
HttpResponse response = null;
HttpEntity entity = null;
try
{
response = httpclient.execute(httpReq);
entity = response.getEntity();
}
catch (IOException ioe)
{
throw new RuntimeException(ioe);
}
if (entity == null)
{
String errMsg = "No response entity back from " + url;
throw new RuntimeException(errMsg);
}
String returnRes = null;
InputStream is = null;
BufferedReader buf = null;
try
{
is = entity.getContent();
buf = new BufferedReader(new InputStreamReader(is, "UTF-8"));
System.out.println("Response Code : " + response.getStatusLine().getStatusCode());
StringBuilder sb = new StringBuilder();
String s = null;
while (true)
{
s = buf.readLine();
if (s == null || s.length() == 0)
{
break;
}
sb.append(s);
}
returnRes = sb.toString();
System.out.println("Response: [" + returnRes + "]");
}
catch (UnsupportedOperationException | IOException e)
{
throw new RuntimeException(e);
}
finally
{
if (buf != null)
{
try
{
buf.close();
}
catch (IOException e)
{
}
}
if (is != null)
{
try
{
is.close();
}
catch (IOException e)
{
}
}
}
return returnRes;
}
}
Outputs:
Response Code : 404
Response: [false,Unknown-Username]
I am successfully using this code to send HTTP requests with some parameters via GET method
void sendRequest(String request)
{
// i.e.: request = "http://example.com/index.php?param1=a¶m2=b¶m3=c";
URL url = new URL(request);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setInstanceFollowRedirects(false);
connection.setRequestMethod("GET");
connection.setRequestProperty("Content-Type", "text/plain");
connection.setRequestProperty("charset", "utf-8");
connection.connect();
}
Now I may need to send the parameters (i.e. param1, param2, param3) via POST method because they are very long.
I was thinking to add an extra parameter to that method (i.e. String httpMethod).
How can I change the code above as little as possible to be able to send paramters either via GET or POST?
I was hoping that changing
connection.setRequestMethod("GET");
to
connection.setRequestMethod("POST");
would have done the trick, but the parameters are still sent via GET method.
Has HttpURLConnection got any method that would help?
Is there any helpful Java construct?
Any help would be very much appreciated.
In a GET request, the parameters are sent as part of the URL.
In a POST request, the parameters are sent as a body of the request, after the headers.
To do a POST with HttpURLConnection, you need to write the parameters to the connection after you have opened the connection.
This code should get you started:
String urlParameters = "param1=a¶m2=b¶m3=c";
byte[] postData = urlParameters.getBytes( StandardCharsets.UTF_8 );
int postDataLength = postData.length;
String request = "http://example.com/index.php";
URL url = new URL( request );
HttpURLConnection conn= (HttpURLConnection) url.openConnection();
conn.setDoOutput( true );
conn.setInstanceFollowRedirects( false );
conn.setRequestMethod( "POST" );
conn.setRequestProperty( "Content-Type", "application/x-www-form-urlencoded");
conn.setRequestProperty( "charset", "utf-8");
conn.setRequestProperty( "Content-Length", Integer.toString( postDataLength ));
conn.setUseCaches( false );
try( DataOutputStream wr = new DataOutputStream( conn.getOutputStream())) {
wr.write( postData );
}
Here is a simple example that submits a form then dumps the result page to System.out. Change the URL and the POST params as appropriate, of course:
import java.io.*;
import java.net.*;
import java.util.*;
class Test {
public static void main(String[] args) throws Exception {
URL url = new URL("http://example.net/new-message.php");
Map<String,Object> params = new LinkedHashMap<>();
params.put("name", "Freddie the Fish");
params.put("email", "fishie#seamail.example.com");
params.put("reply_to_thread", 10394);
params.put("message", "Shark attacks in Botany Bay have gotten out of control. We need more defensive dolphins to protect the schools here, but Mayor Porpoise is too busy stuffing his snout with lobsters. He's so shellfish.");
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"));
for (int c; (c = in.read()) >= 0;)
System.out.print((char)c);
}
}
If you want the result as a String instead of directly printed out do:
StringBuilder sb = new StringBuilder();
for (int c; (c = in.read()) >= 0;)
sb.append((char)c);
String response = sb.toString();
I couldn't get Alan's example to actually do the post, so I ended up with this:
String urlParameters = "param1=a¶m2=b¶m3=c";
URL url = new URL("http://example.com/index.php");
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());
writer.write(urlParameters);
writer.flush();
String line;
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
writer.close();
reader.close();
I find HttpURLConnection really cumbersome to use. And you have to write a lot of boilerplate, error prone code. I needed a lightweight wrapper for my Android projects and came out with a library which you can use as well: DavidWebb.
The above example could be written like this:
Webb webb = Webb.create();
webb.post("http://example.com/index.php")
.param("param1", "a")
.param("param2", "b")
.param("param3", "c")
.ensureSuccess()
.asVoid();
You can find a list of alternative libraries on the link provided.
import java.net.*;
public class Demo{
public static void main(){
String data = "data=Hello+World!";
URL url = new URL("http://localhost:8084/WebListenerServer/webListener");
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestMethod("POST");
con.setDoOutput(true);
con.getOutputStream().write(data.getBytes("UTF-8"));
con.getInputStream();
}
}
i have read above answers and have created a utility class to simplify HTTP request. i hope it will help you.
Method Call
// send params with Hash Map
HashMap<String, String> params = new HashMap<String, String>();
params.put("email","me#example.com");
params.put("password","12345");
//server url
String url = "http://www.example.com";
// static class "HttpUtility" with static method "newRequest(url,method,callback)"
HttpUtility.newRequest(url,HttpUtility.METHOD_POST,params, new HttpUtility.Callback() {
#Override
public void OnSuccess(String response) {
// on success
System.out.println("Server OnSuccess response="+response);
}
#Override
public void OnError(int status_code, String message) {
// on error
System.out.println("Server OnError status_code="+status_code+" message="+message);
}
});
Utility Class
import java.io.*;
import java.net.*;
import java.util.HashMap;
import java.util.Map;
import static java.net.HttpURLConnection.HTTP_OK;
public class HttpUtility {
public static final int METHOD_GET = 0; // METHOD GET
public static final int METHOD_POST = 1; // METHOD POST
// Callback interface
public interface Callback {
// abstract methods
public void OnSuccess(String response);
public void OnError(int status_code, String message);
}
// static method
public static void newRequest(String web_url, int method, HashMap < String, String > params, Callback callback) {
// thread for handling async task
new Thread(new Runnable() {
#Override
public void run() {
try {
String url = web_url;
// write GET params,append with url
if (method == METHOD_GET && params != null) {
for (Map.Entry < String, String > item: params.entrySet()) {
String key = URLEncoder.encode(item.getKey(), "UTF-8");
String value = URLEncoder.encode(item.getValue(), "UTF-8");
if (!url.contains("?")) {
url += "?" + key + "=" + value;
} else {
url += "&" + key + "=" + value;
}
}
}
HttpURLConnection urlConnection = (HttpURLConnection) new URL(url).openConnection();
urlConnection.setUseCaches(false);
urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); // handle url encoded form data
urlConnection.setRequestProperty("charset", "utf-8");
if (method == METHOD_GET) {
urlConnection.setRequestMethod("GET");
} else if (method == METHOD_POST) {
urlConnection.setDoOutput(true); // write POST params
urlConnection.setRequestMethod("POST");
}
//write POST data
if (method == METHOD_POST && params != null) {
StringBuilder postData = new StringBuilder();
for (Map.Entry < String, String > item: params.entrySet()) {
if (postData.length() != 0) postData.append('&');
postData.append(URLEncoder.encode(item.getKey(), "UTF-8"));
postData.append('=');
postData.append(URLEncoder.encode(String.valueOf(item.getValue()), "UTF-8"));
}
byte[] postDataBytes = postData.toString().getBytes("UTF-8");
urlConnection.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length));
urlConnection.getOutputStream().write(postDataBytes);
}
// server response code
int responseCode = urlConnection.getResponseCode();
if (responseCode == HTTP_OK && callback != null) {
BufferedReader reader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
StringBuilder response = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
response.append(line);
}
// callback success
callback.OnSuccess(response.toString());
reader.close(); // close BufferReader
} else if (callback != null) {
// callback error
callback.OnError(responseCode, urlConnection.getResponseMessage());
}
urlConnection.disconnect(); // disconnect connection
} catch (IOException e) {
e.printStackTrace();
if (callback != null) {
// callback error
callback.OnError(500, e.getLocalizedMessage());
}
}
}
}).start(); // start thread
}
}
I see some other answers have given the alternative, I personally think that intuitively you're doing the right thing ;). Sorry, at devoxx where several speakers have been ranting about this sort of thing.
That's why I personally use Apache's HTTPClient/HttpCore libraries to do this sort of work, I find their API to be easier to use than Java's native HTTP support. YMMV of course!
GET and POST method set like this... Two types for api calling 1)get() and 2) post() . get() method to get value from api json array to get value & post() method use in our data post in url and get response.
public class HttpClientForExample {
private final String USER_AGENT = "Mozilla/5.0";
public static void main(String[] args) throws Exception {
HttpClientExample http = new HttpClientExample();
System.out.println("Testing 1 - Send Http GET request");
http.sendGet();
System.out.println("\nTesting 2 - Send Http POST request");
http.sendPost();
}
// HTTP GET request
private void sendGet() throws Exception {
String url = "http://www.google.com/search?q=developer";
HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet(url);
// add request header
request.addHeader("User-Agent", USER_AGENT);
HttpResponse response = client.execute(request);
System.out.println("\nSending 'GET' request to URL : " + url);
System.out.println("Response Code : " +
response.getStatusLine().getStatusCode());
BufferedReader rd = new BufferedReader(
new InputStreamReader(response.getEntity().getContent()));
StringBuffer result = new StringBuffer();
String line = "";
while ((line = rd.readLine()) != null) {
result.append(line);
}
System.out.println(result.toString());
}
// HTTP POST request
private void sendPost() throws Exception {
String url = "https://selfsolve.apple.com/wcResults.do";
HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost(url);
// add header
post.setHeader("User-Agent", USER_AGENT);
List<NameValuePair> urlParameters = new ArrayList<NameValuePair>();
urlParameters.add(new BasicNameValuePair("sn", "C02G8416DRJM"));
urlParameters.add(new BasicNameValuePair("cn", ""));
urlParameters.add(new BasicNameValuePair("locale", ""));
urlParameters.add(new BasicNameValuePair("caller", ""));
urlParameters.add(new BasicNameValuePair("num", "12345"));
post.setEntity(new UrlEncodedFormEntity(urlParameters));
HttpResponse response = client.execute(post);
System.out.println("\nSending 'POST' request to URL : " + url);
System.out.println("Post parameters : " + post.getEntity());
System.out.println("Response Code : " +
response.getStatusLine().getStatusCode());
BufferedReader rd = new BufferedReader(
new InputStreamReader(response.getEntity().getContent()));
StringBuffer result = new StringBuffer();
String line = "";
while ((line = rd.readLine()) != null) {
result.append(line);
}
System.out.println(result.toString());
}
}
I had the same issue. I wanted to send data via POST.
I used the following code:
URL url = new URL("http://example.com/getval.php");
Map<String,Object> params = new LinkedHashMap<>();
params.put("param1", param1);
params.put("param2", param2);
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"));
}
String urlParameters = postData.toString();
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());
writer.write(urlParameters);
writer.flush();
String result = "";
String line;
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
while ((line = reader.readLine()) != null) {
result += line;
}
writer.close();
reader.close()
System.out.println(result);
I used Jsoup for parse:
Document doc = Jsoup.parseBodyFragment(value);
Iterator<Element> opts = doc.select("option").iterator();
for (;opts.hasNext();) {
Element item = opts.next();
if (item.hasAttr("value")) {
System.out.println(item.attr("value"));
}
}
Try this pattern:
public static PricesResponse getResponse(EventRequestRaw request) {
// String urlParameters = "param1=a¶m2=b¶m3=c";
String urlParameters = Piping.serialize(request);
HttpURLConnection conn = RestClient.getPOSTConnection(endPoint, urlParameters);
PricesResponse response = null;
try {
// POST
OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());
writer.write(urlParameters);
writer.flush();
// RESPONSE
BufferedReader reader = new BufferedReader(new InputStreamReader((conn.getInputStream()), StandardCharsets.UTF_8));
String json = Buffering.getString(reader);
response = (PricesResponse) Piping.deserialize(json, PricesResponse.class);
writer.close();
reader.close();
} catch (Exception e) {
e.printStackTrace();
}
conn.disconnect();
System.out.println("PricesClient: " + response.toString());
return response;
}
public static HttpURLConnection getPOSTConnection(String endPoint, String urlParameters) {
return RestClient.getConnection(endPoint, "POST", urlParameters);
}
public static HttpURLConnection getConnection(String endPoint, String method, String urlParameters) {
System.out.println("ENDPOINT " + endPoint + " METHOD " + method);
HttpURLConnection conn = null;
try {
URL url = new URL(endPoint);
conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod(method);
conn.setDoOutput(true);
conn.setRequestProperty("Content-Type", "text/plain");
} catch (IOException e) {
e.printStackTrace();
}
return conn;
}
This answer covers the specific case of the POST Call using a Custom Java POJO.
Using maven dependency for Gson to serialize our Java Object to JSON.
Install Gson using the dependency below.
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.8.5</version>
<scope>compile</scope>
</dependency>
For those using gradle can use the below
dependencies {
implementation 'com.google.code.gson:gson:2.8.5'
}
Other imports used:
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.*;
import org.apache.http.impl.client.CloseableHttpClient;
import com.google.gson.Gson;
Now, we can go ahead and use the HttpPost provided by Apache
private CloseableHttpClient httpclient = HttpClients.createDefault();
HttpPost httppost = new HttpPost("https://example.com");
Product product = new Product(); //custom java object to be posted as Request Body
Gson gson = new Gson();
String client = gson.toJson(product);
httppost.setEntity(new StringEntity(client, ContentType.APPLICATION_JSON));
httppost.setHeader("RANDOM-HEADER", "headervalue");
//Execute and get the response.
HttpResponse response = null;
try {
response = httpclient.execute(httppost);
} catch (IOException e) {
throw new InternalServerErrorException("Post fails");
}
Response.Status responseStatus = Response.Status.fromStatusCode(response.getStatusLine().getStatusCode());
return Response.status(responseStatus).build();
The above code will return with the response code received from the POST Call
here i sent jsonobject as parameter //jsonobject={"name":"lucifer","pass":"abc"}//serverUrl = "http://192.168.100.12/testing" //host=192.168.100.12
public static String getJson(String serverUrl,String host,String jsonobject){
StringBuilder sb = new StringBuilder();
String http = serverUrl;
HttpURLConnection urlConnection = null;
try {
URL url = new URL(http);
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setDoOutput(true);
urlConnection.setRequestMethod("POST");
urlConnection.setUseCaches(false);
urlConnection.setConnectTimeout(50000);
urlConnection.setReadTimeout(50000);
urlConnection.setRequestProperty("Content-Type", "application/json");
urlConnection.setRequestProperty("Host", host);
urlConnection.connect();
//You Can also Create JSONObject here
OutputStreamWriter out = new OutputStreamWriter(urlConnection.getOutputStream());
out.write(jsonobject);// here i sent the parameter
out.close();
int HttpResult = urlConnection.getResponseCode();
if (HttpResult == HttpURLConnection.HTTP_OK) {
BufferedReader br = new BufferedReader(new InputStreamReader(
urlConnection.getInputStream(), "utf-8"));
String line = null;
while ((line = br.readLine()) != null) {
sb.append(line + "\n");
}
br.close();
Log.e("new Test", "" + sb.toString());
return sb.toString();
} else {
Log.e(" ", "" + urlConnection.getResponseMessage());
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
} finally {
if (urlConnection != null)
urlConnection.disconnect();
}
return null;
}
Hello pls use this class to improve your post method
public static JSONObject doPostRequest(HashMap<String, String> data, String url) {
try {
RequestBody requestBody;
MultipartBuilder mBuilder = new MultipartBuilder().type(MultipartBuilder.FORM);
if (data != null) {
for (String key : data.keySet()) {
String value = data.get(key);
Utility.printLog("Key Values", key + "-----------------" + value);
mBuilder.addFormDataPart(key, value);
}
} else {
mBuilder.addFormDataPart("temp", "temp");
}
requestBody = mBuilder.build();
Request request = new Request.Builder()
.url(url)
.post(requestBody)
.build();
OkHttpClient client = new OkHttpClient();
Response response = client.newCall(request).execute();
String responseBody = response.body().string();
Utility.printLog("URL", url);
Utility.printLog("Response", responseBody);
return new JSONObject(responseBody);
} catch (UnknownHostException | UnsupportedEncodingException e) {
JSONObject jsonObject=new JSONObject();
try {
jsonObject.put("status","false");
jsonObject.put("message",e.getLocalizedMessage());
} catch (JSONException e1) {
e1.printStackTrace();
}
Log.e(TAG, "Error: " + e.getLocalizedMessage());
} catch (Exception e) {
e.printStackTrace();
JSONObject jsonObject=new JSONObject();
try {
jsonObject.put("status","false");
jsonObject.put("message",e.getLocalizedMessage());
} catch (JSONException e1) {
e1.printStackTrace();
}
Log.e(TAG, "Other Error: " + e.getLocalizedMessage());
}
return null;
}
I higly recomend http-request built on apache http api.
For your case you can see example:
private static final HttpRequest<String.class> HTTP_REQUEST =
HttpRequestBuilder.createPost("http://example.com/index.php", String.class)
.responseDeserializer(ResponseDeserializer.ignorableDeserializer())
.build();
public void sendRequest(String request){
String parameters = request.split("\\?")[1];
ResponseHandler<String> responseHandler =
HTTP_REQUEST.executeWithQuery(parameters);
System.out.println(responseHandler.getStatusCode());
System.out.println(responseHandler.get()); //prints response body
}
If you are not interested in the response body
private static final HttpRequest<?> HTTP_REQUEST =
HttpRequestBuilder.createPost("http://example.com/index.php").build();
public void sendRequest(String request){
ResponseHandler<String> responseHandler =
HTTP_REQUEST.executeWithQuery(parameters);
}
For general sending post request with http-request: Read the documentation and see my answers HTTP POST request with JSON String in JAVA, Sending HTTP POST Request In Java, HTTP POST using JSON in Java
I took Boann's answer and used it to create a more flexible query string builder that supports lists and arrays, just like php's http_build_query method:
public static byte[] httpBuildQueryString(Map<String, Object> postsData) throws UnsupportedEncodingException {
StringBuilder postData = new StringBuilder();
for (Map.Entry<String,Object> param : postsData.entrySet()) {
if (postData.length() != 0) postData.append('&');
Object value = param.getValue();
String key = param.getKey();
if(value instanceof Object[] || value instanceof List<?>)
{
int size = value instanceof Object[] ? ((Object[])value).length : ((List<?>)value).size();
for(int i = 0; i < size; i++)
{
Object val = value instanceof Object[] ? ((Object[])value)[i] : ((List<?>)value).get(i);
if(i>0) postData.append('&');
postData.append(URLEncoder.encode(key + "[" + i + "]", "UTF-8"));
postData.append('=');
postData.append(URLEncoder.encode(String.valueOf(val), "UTF-8"));
}
}
else
{
postData.append(URLEncoder.encode(key, "UTF-8"));
postData.append('=');
postData.append(URLEncoder.encode(String.valueOf(value), "UTF-8"));
}
}
return postData.toString().getBytes("UTF-8");
}
For those having trouble receiving the request on a php page using $_POST because you expect key-value pairs:
While all the answers where very helpful, I lacked some basic understanding on which string actually to post, since in the old apache HttpClient I used
new UrlEncodedFormEntity(nameValuePairs); (Java)
and then could use $_POST in php do get the key-value pairs.
To my understanding now one has build that string manually before posting. So the string needs to look like
val data = "key1=val1&key2=val2"
but instead just adding it to the url it is posted (in the header).
The alternative would be to use a json-string instead:
val data = "{\"key1\":\"val1\",\"key2\":\"val2\"}" // {"key1":"val1","key2":"val2"}
and pull it in php without $_POST:
$json_params = file_get_contents('php://input');
// echo_p("Data: $json_params");
$data = json_decode($json_params, true);
Here you find a sample code in Kotlin:
class TaskDownloadTest : AsyncTask<Void, Void, Void>() {
override fun doInBackground(vararg params: Void): Void? {
var urlConnection: HttpURLConnection? = null
try {
val postData = JsonObject()
postData.addProperty("key1", "val1")
postData.addProperty("key2", "val2")
// reformat json to key1=value1&key2=value2
// keeping json because I may change the php part to interpret json requests, could be a HashMap instead
val keys = postData.keySet()
var request = ""
keys.forEach { key ->
// Log.i("data", key)
request += "$key=${postData.get(key)}&"
}
request = request.replace("\"", "").removeSuffix("&")
val requestLength = request.toByteArray().size
// Warning in Android 9 you need to add a line in the application part of the manifest: android:usesCleartextTraffic="true"
// https://stackoverflow.com/questions/45940861/android-8-cleartext-http-traffic-not-permitted
val url = URL("http://10.0.2.2/getdata.php")
urlConnection = url.openConnection() as HttpURLConnection
// urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded") // apparently default
// Not sure what these are for, I do not use them
// urlConnection.setRequestProperty("Content-Type", "application/json")
// urlConnection.setRequestProperty("Key","Value")
urlConnection.readTimeout = 5000
urlConnection.connectTimeout = 5000
urlConnection.requestMethod = "POST"
urlConnection.doOutput = true
// urlConnection.doInput = true
urlConnection.useCaches = false
urlConnection.setFixedLengthStreamingMode(requestLength)
// urlConnection.setChunkedStreamingMode(0) // if you do not want to handle request length which is fine for small requests
val out = urlConnection.outputStream
val writer = BufferedWriter(
OutputStreamWriter(
out, "UTF-8"
)
)
writer.write(request)
// writer.write("{\"key1\":\"val1\",\"key2\":\"val2\"}") // {"key1":"val1","key2":"val2"} JsonFormat or just postData.toString() for $json_params=file_get_contents('php://input'); json_decode($json_params, true); in php
// writer.write("key1=val1&key2=val2") // key=value format for $_POST in php
writer.flush()
writer.close()
out.close()
val code = urlConnection.responseCode
if (code != 200) {
throw IOException("Invalid response from server: $code")
}
val rd = BufferedReader(
InputStreamReader(
urlConnection.inputStream
)
)
var line = rd.readLine()
while (line != null) {
Log.i("data", line)
line = rd.readLine()
}
} catch (e: Exception) {
e.printStackTrace()
} finally {
urlConnection?.disconnect()
}
return null
}
}
Now I had to do an HTTP request class, it is probably not the most efficient class, but it works.
I collected some codes from this page and made it more dynamic.
Anyone who needs a complete code, I attached it below.
For an example of how to use it, you can look at the main method.
Also, if you are willing to improve classes online, you are more than welcome to help me make this class better.
import java.net.*;
import java.util.*;
import java.nio.charset.*;
import java.io.*;
public class HttpRequest {
String result = "";
HttpRequest(String _url, String _method, Map<String, String> _postData, String _contentType) {
try {
URL url = new URL( _url );
URLConnection con = url.openConnection();
HttpURLConnection http = (HttpURLConnection)con;
http.setRequestMethod(_method); // PUT is another valid option
http.setDoOutput(true);
StringJoiner sj = new StringJoiner("&");
for(Map.Entry<String,String> entry : _postData.entrySet())
sj.add(URLEncoder.encode(entry.getKey(), "UTF-8") + "=" + entry.getValue());
//sj.add(URLEncoder.encode(entry.getKey(), "UTF-8") + "=" + URLEncoder.encode(entry.getValue()));
byte[] out = sj.toString().getBytes(StandardCharsets.UTF_8);
int length = out.length;
http.setFixedLengthStreamingMode(length);
http.setRequestProperty("Content-Type", _contentType);
http.setRequestProperty( "charset", "utf-8");
http.setRequestProperty( "Content-Length", Integer.toString( length ));
http.setInstanceFollowRedirects( false );
http.setUseCaches( false );
http.connect();
try(OutputStream os = http.getOutputStream()) {
os.write(out);
}
if (http.getResponseCode() == HttpURLConnection.HTTP_OK) {
try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(http.getInputStream()))) {
String line;
while ((line = bufferedReader.readLine()) != null) {
result = result + line;
}
}
} else {
System.out.println("Bad response!");
}
}catch (IOException e) {
// writing exception to log
e.printStackTrace();
}
}
HttpRequest(String _url, String _method, Map<String, String> _postData) {
this(_url, _method, _postData, "text/html");
}
HttpRequest(String _url, String _method) {
this(_url, _method, new HashMap<String, String>());
}
HttpRequest(String _url) {
this(_url, "GET");
}
public String toString() {
return result;
}
public static void main(String[] args) {
// TODO Auto-generated method stub
Map<String, String> postData = new HashMap<String, String>();
postData.putIfAbsent("email", "test#test.com");
postData.putIfAbsent("password", "test");
HttpRequest result = new HttpRequest("https://httpbin.org/anything", "POST", postData, "application/x-www-form-urlencoded");
System.out.println(result.toString());
}
}
Appears that you also have to callconnection.getOutputStream() "at least once" (as well as setDoOutput(true)) for it to treat it as a POST.
So the minimum required code is:
URL url = new URL(urlString);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
//connection.setRequestMethod("POST"); this doesn't seem to do anything at all..so not useful
connection.setDoOutput(true); // set it to POST...not enough by itself however, also need the getOutputStream call...
connection.connect();
connection.getOutputStream().close();
You can even use "GET" style parameters in the urlString, surprisingly. Though that might confuse things.
You can also use NameValuePair apparently.
I am trying to mimic the functionality of this curl command in Java:
curl --basic --user username:password -d "" http://ipaddress/test/login
I wrote the following using Commons HttpClient 3.0 but somehow ended up getting an 500 Internal Server Error from the server. Can someone tell me if I'm doing anything wrong?
public class HttpBasicAuth {
private static final String ENCODING = "UTF-8";
/**
* #param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
try {
HttpClient client = new HttpClient();
client.getState().setCredentials(
new AuthScope("ipaddress", 443, "realm"),
new UsernamePasswordCredentials("test1", "test1")
);
PostMethod post = new PostMethod(
"http://address/test/login");
post.setDoAuthentication( true );
try {
int status = client.executeMethod( post );
System.out.println(status + "\n" + post.getResponseBodyAsString());
} finally {
// release any connection resources used by the method
post.releaseConnection();
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
And I later tried a Commons HttpClient 4.0.1 but still the same error:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.auth.AuthScope;
import org.apache.http.auth.UsernamePasswordCredentials;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
public class HttpBasicAuth {
private static final String ENCODING = "UTF-8";
/**
* #param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
try {
DefaultHttpClient httpclient = new DefaultHttpClient();
httpclient.getCredentialsProvider().setCredentials(
new AuthScope(AuthScope.ANY_HOST, AuthScope.ANY_PORT),
new UsernamePasswordCredentials("test1", "test1"));
HttpPost httppost = new HttpPost("http://host:post/test/login");
System.out.println("executing request " + httppost.getRequestLine());
HttpResponse response;
response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
System.out.println("----------------------------------------");
System.out.println(response.getStatusLine());
if (entity != null) {
System.out.println("Response content length: " + entity.getContentLength());
}
if (entity != null) {
entity.consumeContent();
}
httpclient.getConnectionManager().shutdown();
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
Have you tried this (using HttpClient version 4):
String encoding = Base64.getEncoder().encodeToString((user + ":" + pwd).getBytes());
HttpPost httpPost = new HttpPost("http://host:post/test/login");
httpPost.setHeader(HttpHeaders.AUTHORIZATION, "Basic " + encoding);
System.out.println("executing request " + httpPost.getRequestLine());
HttpResponse response = httpClient.execute(httpPost);
HttpEntity entity = response.getEntity();
Ok so this one works. Just in case anybody wants it, here's the version that works for me :)
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Base64;
public class HttpBasicAuth {
public static void main(String[] args) {
try {
URL url = new URL ("http://ip:port/login");
String encoding = Base64.getEncoder().encodeToString(("test1:test1").getBytes("UTF-8"));
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("POST");
connection.setDoOutput(true);
connection.setRequestProperty ("Authorization", "Basic " + encoding);
InputStream content = (InputStream)connection.getInputStream();
BufferedReader in =
new BufferedReader (new InputStreamReader (content));
String line;
while ((line = in.readLine()) != null) {
System.out.println(line);
}
} catch(Exception e) {
e.printStackTrace();
}
}
}
This is the code from the accepted answer above, with some changes made regarding the Base64 encoding. The code below compiles.
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import org.apache.commons.codec.binary.Base64;
public class HttpBasicAuth {
public static void main(String[] args) {
try {
URL url = new URL ("http://ip:port/login");
Base64 b = new Base64();
String encoding = b.encodeAsString(new String("test1:test1").getBytes());
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("POST");
connection.setDoOutput(true);
connection.setRequestProperty ("Authorization", "Basic " + encoding);
InputStream content = (InputStream)connection.getInputStream();
BufferedReader in =
new BufferedReader (new InputStreamReader (content));
String line;
while ((line = in.readLine()) != null) {
System.out.println(line);
}
}
catch(Exception e) {
e.printStackTrace();
}
}
}
A small update - hopefully useful for somebody - it works for me in my project:
I use the nice Public Domain class Base64.java from Robert Harder (Thanks Robert - Code availble here: Base64 - download and put it in your package).
and make a download of a file (image, doc, etc.) with authentication and write to local disk
Example:
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
public class HttpBasicAuth {
public static void downloadFileWithAuth(String urlStr, String user, String pass, String outFilePath) {
try {
// URL url = new URL ("http://ip:port/download_url");
URL url = new URL(urlStr);
String authStr = user + ":" + pass;
String authEncoded = Base64.encodeBytes(authStr.getBytes());
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setDoOutput(true);
connection.setRequestProperty("Authorization", "Basic " + authEncoded);
File file = new File(outFilePath);
InputStream in = (InputStream) connection.getInputStream();
OutputStream out = new BufferedOutputStream(new FileOutputStream(file));
for (int b; (b = in.read()) != -1;) {
out.write(b);
}
out.close();
in.close();
}
catch (Exception e) {
e.printStackTrace();
}
}
}
Here are a few points:
You could consider upgrading to HttpClient 4 (generally speaking, if you can, I don't think version 3 is still actively supported).
A 500 status code is a server error, so it might be useful to see what the server says (any clue in the response body you're printing?). Although it might be caused by your client, the server shouldn't fail this way (a 4xx error code would be more appropriate if the request is incorrect).
I think setDoAuthentication(true) is the default (not sure). What could be useful to try is pre-emptive authentication works better:
client.getParams().setAuthenticationPreemptive(true);
Otherwise, the main difference between curl -d "" and what you're doing in Java is that, in addition to Content-Length: 0, curl also sends Content-Type: application/x-www-form-urlencoded. Note that in terms of design, you should probably send an entity with your POST request anyway.
while using Header array
String auth = Base64.getEncoder().encodeToString(("test1:test1").getBytes());
Header[] headers = {
new BasicHeader(HTTP.CONTENT_TYPE, ContentType.APPLICATION_JSON.toString()),
new BasicHeader("Authorization", "Basic " +auth)
};
Thanks for all answers above, but for me, I can not find Base64Encoder class, so I sort out my way anyway.
public static void main(String[] args) {
try {
DefaultHttpClient Client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet("https://httpbin.org/basic-auth/user/passwd");
String encoding = DatatypeConverter.printBase64Binary("user:passwd".getBytes("UTF-8"));
httpGet.setHeader("Authorization", "Basic " + encoding);
HttpResponse response = Client.execute(httpGet);
System.out.println("response = " + response);
BufferedReader breader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
StringBuilder responseString = new StringBuilder();
String line = "";
while ((line = breader.readLine()) != null) {
responseString.append(line);
}
breader.close();
String repsonseStr = responseString.toString();
System.out.println("repsonseStr = " + repsonseStr);
} catch (IOException e) {
e.printStackTrace();
}
}
One more thing, I also tried
Base64.encodeBase64String("user:passwd".getBytes());
It does NOT work due to it return a string almost same with
DatatypeConverter.printBase64Binary()
but end with "\r\n", then server will return "bad request".
Also following code is working as well, actually I sort out this first, but for some reason, it does NOT work in some cloud environment (sae.sina.com.cn if you want to know, it is a chinese cloud service). so have to use the http header instead of HttpClient credentials.
public static void main(String[] args) {
try {
DefaultHttpClient Client = new DefaultHttpClient();
Client.getCredentialsProvider().setCredentials(
AuthScope.ANY,
new UsernamePasswordCredentials("user", "passwd")
);
HttpGet httpGet = new HttpGet("https://httpbin.org/basic-auth/user/passwd");
HttpResponse response = Client.execute(httpGet);
System.out.println("response = " + response);
BufferedReader breader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
StringBuilder responseString = new StringBuilder();
String line = "";
while ((line = breader.readLine()) != null) {
responseString.append(line);
}
breader.close();
String responseStr = responseString.toString();
System.out.println("responseStr = " + responseStr);
} catch (IOException e) {
e.printStackTrace();
}
}
An easy way to login with a HTTP POST without doing any Base64 specific calls is to use the HTTPClient BasicCredentialsProvider
import java.io.IOException;
import static java.lang.System.out;
import org.apache.http.HttpResponse;
import org.apache.http.auth.AuthScope;
import org.apache.http.auth.UsernamePasswordCredentials;
import org.apache.http.client.CredentialsProvider;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.BasicCredentialsProvider;
import org.apache.http.impl.client.HttpClientBuilder;
//code
CredentialsProvider provider = new BasicCredentialsProvider();
UsernamePasswordCredentials credentials = new UsernamePasswordCredentials(user, password);
provider.setCredentials(AuthScope.ANY, credentials);
HttpClient client = HttpClientBuilder.create().setDefaultCredentialsProvider(provider).build();
HttpResponse response = client.execute(new HttpPost("http://address/test/login"));//Replace HttpPost with HttpGet if you need to perform a GET to login
int statusCode = response.getStatusLine().getStatusCode();
out.println("Response Code :"+ statusCode);
for HttpClient always use HttpRequestInterceptor
for example
httclient.addRequestInterceptor(new HttpRequestInterceptor() {
public void process(HttpRequest arg0, HttpContext context) throws HttpException, IOException {
AuthState state = (AuthState) context.getAttribute(ClientContext.TARGET_AUTH_STATE);
if (state.getAuthScheme() == null) {
BasicScheme scheme = new BasicScheme();
CredentialsProvider credentialsProvider = (CredentialsProvider) context.getAttribute(ClientContext.CREDS_PROVIDER);
Credentials credentials = credentialsProvider.getCredentials(AuthScope.ANY);
if (credentials == null) {
System.out.println("Credential >>" + credentials);
throw new HttpException();
}
state.setAuthScope(AuthScope.ANY);
state.setAuthScheme(scheme);
state.setCredentials(credentials);
}
}
}, 0);
HttpBasicAuth works for me with smaller changes
I use maven dependency
<dependency>
<groupId>net.iharder</groupId>
<artifactId>base64</artifactId>
<version>2.3.8</version>
</dependency>
Smaller change
String encoding = Base64.encodeBytes ((user + ":" + passwd).getBytes());