Java client POST to php script - empty $_POST

Question

I have researched extensively and cannot find a solution. I have been using the solutions provided to other users and it does not seem to work for me.

My java code:

public class Post {
public static void main(String[] args) { 
    String name = "Bobby";
    String address = "123 Main St., Queens, NY";
    String phone = "4445556666";

    String data = "";
    try { 
        // POST as urlencoded is basically key-value pairs
        // create key=value&key=value.... pairs
        data += "name=" + URLEncoder.encode(name, "UTF-8");
        data += "&address=" + 
            URLEncoder.encode(address, "UTF-8");
        data += "&phone=" + 
            URLEncoder.encode(phone, "UTF-8");

        // convert string to byte array, as it should be sent
        byte[] dataBytes = data.toString().getBytes("UTF-8");

        // open a connection to the site
        URL url = new URL("http://xx.xx.xx.xxx/yyy.php");
        HttpURLConnection conn = 
            (HttpURLConnection) url.openConnection();

        // tell the server this is POST & the format of the data.
        conn.setDoOutput(true);
        conn.setRequestProperty("Content-Type",
                "application/x-www-form-urlencoded");
        conn.setRequestMethod("POST");
        conn.setFixedLengthStreamingMode(dataBytes.length);
        conn.getOutputStream().write(dataBytes);

        conn.getInputStream();
        // Print out the echo statements from the php script
        BufferedReader in = new BufferedReader(
                new InputStreamReader(url.openStream()));

        String line;
        while((line = in.readLine()) != null) 
            System.out.println(line);

        in.close();
    } catch(Exception e) { 
        e.printStackTrace();
    }
}
}

and the php

<?php
echo $_POST["name"];
?>

The output I receive is an empty line. I tested to see if it was a php/server side issue by making an html form that sends data over to a similar script and prints the data on the screen and that worked. But, for the life of me, I cannot get this to work with a remote client. I am using Ubuntu server and Apache. Thank you in advance.

I'd recommend using a proper Java library to make the HTTP request, e.g. github.com/google/google-http-java-client — Michael Lihs
– Michael Lihs, Commented Feb 9, 2017 at 23:09

Andremoniy · Accepted Answer · 2017-02-09 22:57:12Z

2

The problem is actually in what you read as output. You are doing two requests: 1)conn.getInputStream(); - sends POST request with desired body

2)BufferedReader in = new BufferedReader( new InputStreamReader(url.openStream())); - sends empty GET request (!!)

Change it to:

// ...
conn.getOutputStream().write(dataBytes);

BufferedReader in = new BufferedReader(
         new InputStreamReader(conn.getInputStream()));

and see result.

answered Feb 9, 2017 at 22:57

Andremoniy

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1 Comment

BaneDad Over a year ago

That's it! Thank you so much. Looking at the apache logs, you are correct. I was sending an empty GET.

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