php - Sending Data From Android To Server with JSON data

Question

I am trying sending data from Android application to web server. My android application is working successfully.However php code have problems.

<?php
$json = $_SERVER['HTTP_JSON'];
echo "JSON: 
";
var_dump($json);
echo "

";

$data = json_decode($json,true);
echo "Array: 
";
var_dump($data);
echo "

";

$name = $data['name'];
$pos = $data['position'];
echo "Result: 
";
echo "Name     : ".$name."
 Position : ".$pos; 
?>

Errors:

Notice: Undefined index: HTTP_JSON in C:wampwwwjsonTest.php on line 2
( line 2 : $json = $_SERVER['HTTP_JSON']; )

I couldn't find these problems reason. Can you help me ? ( note: I am using wamp server )

Here is the relevant Android source:

// Create a new HttpClient and Post Header 
HttpClient httpclient = new DefaultHttpClient(); 
HttpPost httppost = new HttpPost("10.0.2.2:90/jsonTest.php";); 

JSONObject json = new JSONObject(); 
try { 
    json.put("name", "flower"); 
    json.put("position", "student"); 
    JSONArray postjson=new JSONArray(); 
    postjson.put(json); 
    httppost.setHeader("json",json.toString());
    httppost.getParams().setParameter("jsonpost",postjson); 
    System.out.print(json); 
    HttpResponse response = httpclient.execute(httppost); 

    if(response != null)
    {
    InputStream is = response.getEntity().getContent();

    BufferedReader reader = new BufferedReader(new InputStreamReader(is));
    StringBuilder sb = new StringBuilder();

    String line = null;
    try {
        while ((line = reader.readLine()) != null) {
            sb.append(line + "
");
        }
        } catch (IOException e) {
        e.printStackTrace();
        } finally {
        try {
        is.close();
        } catch (IOException e) {
        e.printStackTrace();
        }
        }
    text = sb.toString();
    }
    tv.setText(text);

}catch (ClientProtocolException e) {
    // TODO Auto-generated catch block
} catch (IOException e) {
    // TODO Auto-generated catch block
}

This code works successfully on android side(no error). But php side has problems.. Thanks.

Answer 1

This isn't where your JSON is:

$json = $_SERVER['HTTP_JSON'];

You possibly meant:

$json = $_POST['HTTP_JSON'];

Where HTTP_JSON is the POST variable name you gave to your JSON in your Android app.

The rest of the errors stem from the fact that json_decode is failing because you're not successfully reading the JSON data from the request. You can check the response of json_decode to check if it was successful as follows:

$data = json_decode($json,true);
if( $data === NULL)
{
    exit( 'Could not decode JSON');
}

Finally, passing true as the second parameter to json_encode means it will return an associative array, so you'd access elements like so:

$name = $data['name'];
$pos = $data['position'];

Make sure you read the docs for json_encode so you understand what it's doing.

Edit: Your problem is that you're accessing the $_POST parameter by the wrong name. You should be using:

$json = $_POST['jsonpost'];

Since the following line names the parameter "jsonpost":

httppost.getParams().setParameter("jsonpost",postjson);