HttpsURLConnection
In this tutorial you will learn how to fetch data from a network over a secure HTTPS connection via HttpsURLConnection.
Step 1: Dependencies
No external dependency is needed.
Step 2: Add Permissions
Add the following two permissions in your AndroidManifest.xml:
<!-- Add Internet capabilities to our application -->
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
Step 3: Design Layout
Design your Activity layout as follows:
activity_network.xml
Place a TextView and a ProgressBar inside a FrameLayout:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="fr.esilv.networkexample.NetworkActivity">
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Hello World!"/>
<ProgressBar
android:id="@+id/progressBar"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:visibility="gone"/>
</FrameLayout>
Step 4: Write Code
Create a NetworkActivity.java and add the following code:
NetworkActivity.java
package fr.esilv.networkexample;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ProgressBar;
import android.widget.TextView;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URL;
import javax.net.ssl.HttpsURLConnection;
public class NetworkActivity extends AppCompatActivity {
private TextView textView;
private ProgressBar progressBar;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_network);
textView = findViewById(R.id.textView);
progressBar = findViewById(R.id.progressBar);
new DownloadTask().execute("https://www.esilv.fr");
}
public NetworkInfo getActiveNetworkInfo() {
ConnectivityManager connectivityManager =
(ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
return networkInfo;
}
/**
* Converts the contents of an InputStream to a String.
*/
public String readStream(InputStream stream, int maxReadSize)
throws IOException {
Reader reader;
reader = new InputStreamReader(stream, "UTF-8");
char[] rawBuffer = new char[maxReadSize];
int readSize;
StringBuffer buffer = new StringBuffer();
while (((readSize = reader.read(rawBuffer)) != -1) && maxReadSize > 0) {
if (readSize > maxReadSize) {
readSize = maxReadSize;
}
buffer.append(rawBuffer, 0, readSize);
maxReadSize -= readSize;
}
return buffer.toString();
}
/**
* Given a URL, sets up a connection and gets the HTTP response body from the server.
* If the network request is successful, it returns the response body in String form. Otherwise,
* it will throw an IOException.
*/
private String downloadUrl(URL url) throws IOException {
InputStream stream = null;
HttpsURLConnection connection = null;
String result = null;
try {
connection = (HttpsURLConnection) url.openConnection();
// Timeout for reading InputStream arbitrarily set to 3000ms.
connection.setReadTimeout(3000);
// Timeout for connection.connect() arbitrarily set to 3000ms.
connection.setConnectTimeout(3000);
// For this use case, set HTTP method to GET.
connection.setRequestMethod("GET");
// Already true by default but setting just in case; needs to be true since this request
// is carrying an input (response) body.
connection.setDoInput(true);
// Open communications link (network traffic occurs here).
connection.connect();
int responseCode = connection.getResponseCode();
if (responseCode != HttpsURLConnection.HTTP_OK) {
throw new IOException("HTTP error code: " + responseCode);
}
// Retrieve the response body as an InputStream.
stream = connection.getInputStream();
if (stream != null) {
// Converts Stream to String with max length of 500.
result = readStream(stream, 2000);
}
} finally {
// Close Stream and disconnect HTTPS connection.
if (stream != null) {
stream.close();
}
if (connection != null) {
connection.disconnect();
}
}
return result;
}
/**
* Implementation of AsyncTask designed to fetch data from the network.
*/
private class DownloadTask extends AsyncTask<String, Integer, String> {
/**
* Cancel background network operation if we do not have network connectivity.
*/
@Override
protected void onPreExecute() {
NetworkInfo networkInfo = getActiveNetworkInfo();
if (networkInfo == null || !networkInfo.isConnected() ||
(networkInfo.getType() != ConnectivityManager.TYPE_WIFI
&& networkInfo.getType() != ConnectivityManager.TYPE_MOBILE)) {
// If no connectivity, cancel task and update Callback with null data.
textView.setText("no network");
cancel(true);
} else {
progressBar.setVisibility(View.VISIBLE);
}
}
/**
* Defines work to perform on the background thread.
*/
@Override
protected String doInBackground(String... urls) {
String result = null;
if (!isCancelled() && urls != null && urls.length > 0) {
String urlString = urls[0];
try {
URL url = new URL(urlString);
result = downloadUrl(url);
} catch (Exception e) {
}
}
return result;
}
/**
* Updates the DownloadCallback with the result.
*/
@Override
protected void onPostExecute(String result) {
progressBar.setVisibility(View.INVISIBLE);
if (result != null) {
textView.setText(result);
}
}
}
}