How to post&get Data through java.net.HttpURLConnection[Android/Java]


This article describes “How to post Data / get Data through java.net.HttpURLConnection to access the webservice”.


Set allow domain to res/xml/network_security_config.xml:

<?xml version="1.0" encoding="utf-8"?>
<network-security-config>
<domain-config usesCleartextTraffic="false">
<domain includeSubdomains="true">example.com</domain>
</domain-config>
</network-security-config>

Sample code for getting or posting data is as follows:

public class PostCall {
private static final String USER_AGENT = "Mozilla/5.0 (Linux; <Android Version>; <Build Tag etc.>) AppleWebKit/<WebKit Rev> (KHTML, like Gecko) Chrome/<Chrome Rev> Mobile Safari/<WebKit Rev>";

public void doSomething() {
String getResult = getUrl(new URL("http://example.com/get_end_point"));

MyRequest request = new MyRequest(something);
String postResult = postJson(new URL(SCRAPED_HTML_URL_END_POINT), new Gson().toJson(request));
String postResult = postJson(new URL("http://example.com/get_end_point"), );
}

private String getUrl(URL url) {
HttpURLConnection c = null;

try{
c = (HttpURLConnection)url.openConnection();
c.setRequestProperty("Content-length", "0");
c.setRequestProperty("User-Agent", USER_AGENT);
c.setRequestMethod("GET");
c.setRequestProperty("Content-Type", "application/json");
c.setUseCaches(false);
c.setAllowUserInteraction(false);
c.setConnectTimeout(3000);
c.setReadTimeout(3000);

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 "";
}

private String postJson(URL url, String json) {
HttpURLConnection c = null;

try{
c = (HttpURLConnection)url.openConnection();
c.setRequestProperty("Content-length", String.valueOf(json.getBytes().length));
c.setRequestProperty("User-Agent", USER_AGENT);
c.setRequestMethod("POST");
c.setRequestProperty("Content-Type", "application/json");
c.setDoInput(true);
c.setDoOutput(true);
c.setUseCaches(false);
c.setAllowUserInteraction(false);
c.setConnectTimeout(3000);
c.setReadTimeout(3000);

OutputStream os = c.getOutputStream();
os.write(json.getBytes());
os.flush();
os.close();

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 "";
}
}

🤔 Create Dummy Endpoint

mockable.io can create your API mock.

🗽 Special Thanks

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