I have a short Android-Java client program which sends a basic information to bottle-python server with POST method. In the first version of code, server does not show anything. However, In the second version it works but I cannot understand what this additional line do because it has anything to do with posting content. I really appreciate if someone helps me figure this out.(There is nothing wrong with the server code since I can properly send request with python requests and my browsers).
This is the first version of client code:
String url = "http://192.168.1.23:8080/";
URL obj = new URL(url);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
con.setDoOutput(true);
OutputStream os = con.getOutputStream();
PrintStream myPusher = new PrintStream(os );
myPusher.print("param1=hey");
Second version:
String url = "http://192.168.1.23:8080/";
URL obj = new URL(url);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
con.setDoOutput(true);
OutputStream os = con.getOutputStream();
PrintStream myPusher = new PrintStream(os );
myPusher.print("param1=hey");
InputStream in= con.getInputStream(); //Nothing changed but only this additional line
Bottle(python) server:
#app.route('/', method="POST")
def hello():
print("it works")
name = request.forms.get("param1")
print(name)
return name
#app.route('/')
def hello():
i=0
print("it works")
run(app, host="192.168.1.23", port=8080)
With first client code server shows nothing.
With second code server shows:
it works
hey
192.168.1.24 - - [31/Dec/2018 17:10:28] "POST / HTTP/1.1" 200 3
Which is as I expected.
With your first code snippet the output stream is still open. So the server does not know if it got the complete request. Probably just closing the stream would work as well.
However, I would make at least a call to getResponseCode to see the outcome of the request.
Your java code seems incomplete for sending a post request.
I think by using this code, you can make it work for yourself.
The PrintStream is a buffered type, this means you should add a flush operation after each print(), or use println() instead.
Related
I'm having problems doing a Postman REST call copying a REST call in Java.
I tried to set request properties on Postman the same way they're set in Java, but it's not working.
I have to send a base64 string with this call (i put in italic the code line where this is done in Java code)
URLConnection connection = new URL(url + content).openConnection();
connection.setDoOutput(true);
connection.setUseCaches(false);
connection.setConnectTimeout(timeout);
((HttpURLConnection) connection).setRequestMethod("POST");
connection.setRequestProperty("Accept", "*/*");
connection.setRequestProperty("Connection", "keep-alive");
connection.setRequestProperty("Content-Type", "application/json; charset=utf-8");
OutputStream output = connection.getOutputStream();
JSONObject conf = new JSONObject();
conf.put("signedEvidence", String.format("%s", baos));
*output.write(conf.toString().getBytes());*
output.flush();
checkHttpStatus(connection);
I configured Postman like this:
And i receive this answer:
EDIT - In few words: the REST call works fine in Java, but i need to do some of these calls in Postman with my own variable (the service i'm calling do some works with base64 string i pass him).
EDIT2 - Main problem, in my opinion, is the line:
output.write(conf.toString().getBytes());
which set the base64 in my Java call, and i don't understand/know how to do the same in my Postman call.
Try only adding the following values:
Then, add the content type and the values which you need to pass.
I requested to send some parameters from java file using post method. I did
String urlParameters = "param1=a¶m2=b¶m3=c";
URL url = new URL("http://testing/index.jsp");
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());
writer.write(urlParameters);
writer.flush();
But from receiver's end asks me to send it in body instead of url parameter. I am not sure what I am doing wrong. Please explain me how this code will work and what changes has to be done if I want to send info in request body.
i believe you either need to call the connect() method on the URLConnection at the end, or call a method that would cause the connect to be called for you, like fetching the resulting input stream.
Also you should think about what format the body should be in. Often people like to use standard formats like json, but you will have to decide that between you and the people implementing the server.
I've read lots and tried lots relating to HTTP POSTS using HttpURLConnection and almost everything I come across has a similar structure which starts with these 3 lines:
url = new URL(targetURL);
connection = (HttpURLConnection)url.openConnection();
connection.setRequestMethod("POST");
When I try this I always get a "Connection Already Established" exception when calling setRequestMethod, which makes perfect sense as I'm clearly calling openConnection before setting the request type. Although reading the docs openConnection doesn't actually open the connection in theory.
There are several posts about this problem on SO such as this and this. I don't understand however why every piece of advice about how to write this code has these 3 lines in this order.
I'm guessing this code must work in most instances as someone must have tested it, so why doesn't this code work for me? How should I be writing this code?
I am aware these are other libraries I can use out there, I'm just wondering why this doesn't work.
Why the suspect code in the question has been duplicated all over the internet is something I can't answer. Nor can I answer why it seems to work for some people and not others. I can however answer the other question now, mainly thanks to this link that Luiggi pointed me to.
The key here is understanding the intricacies of the HttpURLConnection class. When first created the class defaults to a "GET" request method, so nothing needs to be changed in this instance. The following is rather unintuitive, but to set the request method to "POST" you should not call setRequestMethod("POST"), but rather setDoOutput(true) which implicitly sets the request method to post. Once you've done that you're good to go.
Below, I believe, is what a post method should look like. This is for posting json, but can obviously be altered for any other content type.
public static String doPostSync(final String urlToRead, final String content) throws IOException {
final String charset = "UTF-8";
// Create the connection
HttpURLConnection connection = (HttpURLConnection) new URL(urlToRead).openConnection();
// setDoOutput(true) implicitly set's the request type to POST
connection.setDoOutput(true);
connection.setRequestProperty("Accept-Charset", charset);
connection.setRequestProperty("Content-type", "application/json");
// Write to the connection
OutputStream output = connection.getOutputStream();
output.write(content.getBytes(charset));
output.close();
// Check the error stream first, if this is null then there have been no issues with the request
InputStream inputStream = connection.getErrorStream();
if (inputStream == null)
inputStream = connection.getInputStream();
// Read everything from our stream
BufferedReader responseReader = new BufferedReader(new InputStreamReader(inputStream, charset));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = responseReader.readLine()) != null) {
response.append(inputLine);
}
responseReader.close();
return response.toString();
}
As per https://stackoverflow.com/a/3324964/436524, you need to call connection.setDoOutput(true) for it to expect a POST request.
This makes your code like this:
url = new URL(targetURL);
connection = (HttpURLConnection)url.openConnection();
connection.setDoOutput(true);
I am trying to make a HTTPS call using Java to a browser that uses the native login prompt.
http://blog.stevensanderson.com/2008/08/25/using-the-browsers-native-login-prompt/
Currently I'm using the below for HTTP and it works fine for other websites since I know the parameters to put in...however it fails for the above type of login (I am not sure how to capture the parameters...it's a login pop up..or if this is even the correct approach)....any ideas??..thanks
HttpUtility.sendPostRequest(requestURL, params);
String[] response = HttpUtility.readMultipleLinesRespone();
The server should respond to your first request with a WWW-Authenticate header and a status of 401. The header will contain details of the kind of authentication it's expecting.
Then you can try again after adding an Authorization header to your request in the correct format.
#alex: OK...I managed to make the HTTPS connection following your suggestion with this:
URL url = new URL("https://www.example.com/Login");
URLConnection urlConnection = url.openConnection();
urlConnection.setRequestProperty("Authorization", "Basic " + authString);
InputStream is = urlConnection.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
//then I read the input stream..
But when I tried to make another connection (say go to a different page after login) with this code in another method...taking URLConnection as the parameter:
//Below is in a method called account(URLConnection urlConnection)
URL url = new URL("https://www.example.com/account.aspx");
urlConnection = url.openConnection();
InputStream is = urlConnection.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
//again I read the input stream..
...it throws the below exception...same exception before logging in..how can I rectify?
Server returned HTTP response code: 401 for URL: https://www.example.com/account.aspx
You have probably moved on from this problem, but I recently had an issue that involved achieving functionality similar to the browser's native login prompt. I have solved it and written a post about it. Steven Sanderson's post was helpful for me too, in helping me understand certain concepts.
http://captaindanko.blogspot.com.au/2015/04/how-does-browsers-native-login-prompt.html
I have a php page in my server that accepts a couple of POST requests and process them. Lets say it's a simple page and the output is simply an echoed statement. With the URLConnection I established from a Java program to send the POST request, I tried to get the input using the input stream got through connection.getInputStream(). But All I get is the source of the page(the whole php script) and not the output it produces. We shall avoid socket connections here. Can this be done with Url connection or HttpRequest? How?
class htttp{
public static void main(String a[]) throws IOException{
URL url=new URL("http://localhost/test.php");
URLConnection conn = url.openConnection();
//((HttpURLConnection) conn).setRequestMethod("POST");
conn.setDoOutput(true);
conn.setDoInput(true);
OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
wr.write("Hello");
wr.flush();
wr.close();
InputStream ins = conn.getInputStream();
InputStreamReader isr = new InputStreamReader(ins);
BufferedReader in = new BufferedReader(isr);
String inputLine;
String result = "";
while( (inputLine = in.readLine()) != null )
result += inputLine;
System.out.print(result);
}
}
I get the whole source of the webpage test.php in result. But I want only the output of the php script.
The reason you get the PHP source itself, rather than the output it should be rendering, is that your local HTTP server - receiving your request targeted at http://localhost/test.php - decided to serve back the PHP source, rather than forward the HTTP request to a PHP processor to render the output.
Why this happens? that has to do with your HTTP server's configuration; there might be a few reasons for that. For starters, you should validate your HTTP server's configuration.
Which HTTP server are you using on your machine?
What happens when you browse http://localhost/test.php through your browser?
The problem here is not the Java code - the problem lies with the web server. You need to investigate why your webserver is not executing your PHP script but sending it back raw. You can begin by testing using a simple PHP scipt which returns a fixed result and is accessed using a GET request (from a web browser). Once that is working you can test using the one that responds to POST requests.