Parse JSON from HttpURLConnection object

You can get raw data using below method. BTW, this pattern is for Java 6. If you are using Java 7 or newer, please consider try-with-resources pattern.

public String getJSON(String url, int timeout) {    HttpURLConnection c = null;    try {        URL u = new URL(url);        c = (HttpURLConnection) u.openConnection();        c.setRequestMethod("GET");        c.setRequestProperty("Content-length", "0");        c.setUseCaches(false);        c.setAllowUserInteraction(false);        c.setConnectTimeout(timeout);        c.setReadTimeout(timeout);        c.connect();        int status = c.getResponseCode();        switch (status) {            case 200:            case 201:                BufferedReader br = new BufferedReader(new InputStreamReader(c.getInputStream()));                StringBuilder sb = new StringBuilder();                String line;                while ((line = br.readLine()) != null) {                    sb.append(line+"\n");                }                br.close();                return sb.toString();        }    } catch (MalformedURLException ex) {        Logger.getLogger(getClass().getName()).log(Level.SEVERE, null, ex);    } catch (IOException ex) {        Logger.getLogger(getClass().getName()).log(Level.SEVERE, null, ex);    } finally {       if (c != null) {          try {              c.disconnect();          } catch (Exception ex) {             Logger.getLogger(getClass().getName()).log(Level.SEVERE, null, ex);          }       }    }    return null;}

And then you can use returned string with Google Gson to map JSON to object of specified class, like this:

String data = getJSON("http://localhost/authmanager.php");AuthMsg msg = new Gson().fromJson(data, AuthMsg.class);System.out.println(msg);

There is a sample of AuthMsg class:

public class AuthMsg {    private int code;    private String message;    public int getCode() {        return code;    }    public void setCode(int code) {        this.code = code;    }    public String getMessage() {        return message;    }    public void setMessage(String message) {        this.message = message;    }}

JSON returned by http://localhost/authmanager.php must look like this:

{"code":1,"message":"Logged in"}

Regards

Define the following function (not mine, not sure where I found it long ago):

private static String convertStreamToString(InputStream is) {BufferedReader reader = new BufferedReader(new InputStreamReader(is));StringBuilder sb = new StringBuilder();String line = null;try {    while ((line = reader.readLine()) != null) {        sb.append(line + "\n");    }} catch (IOException e) {    e.printStackTrace();} finally {    try {        is.close();    } catch (IOException e) {        e.printStackTrace();    }}return sb.toString();

}

Then:

String jsonReply;if(conn.getResponseCode()==201 || conn.getResponseCode()==200)    {        success = true;        InputStream response = conn.getInputStream();        jsonReply = convertStreamToString(response);        // Do JSON handling here....    }

In addition, if you wish to parse your object in case of http error (400-5** codes),You can use the following code: (just replace 'getInputStream' with 'getErrorStream':

    BufferedReader rd = new BufferedReader(            new InputStreamReader(conn.getErrorStream()));    StringBuilder sb = new StringBuilder();    String line;    while ((line = rd.readLine()) != null) {        sb.append(line);    }    rd.close();    return sb.toString();