Android button to call www address

Question

I need to make a simple app with button that will call some URL. I got an apache server at my Rpi which I use to control GPIO by sending GET URL like this

http://192.168.0.105/index.php?pin=2&status=0.

In android studio I have only made a onclick button.

Problem is that I'm noob at java and android, so here's my question - what's the easiest way to make this button send URL? I found some tutorials about sending or receiving data from server but that's not what I want to do.

Answer 1

You can use this code inside of buttons on click event. To open URL on click.

Intent browserIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("<your URL>"));
startActivity(browserIntent);

Also if you want to connect as a web client, but not want to open in browser - you can use:

DefaultHttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet("http://www.someplace.com");

ResponseHandler<String> resHandler = new BasicResponseHandler();
String page = httpClient.execute(httpGet, resHandler);

Answer 2

1. Add permission to manifest: <uses-permission android:name="android.permission.INTERNET" />

2. Create a class:

   class RequestTask extends AsyncTask<String, String, String> {
       String response;
       ProgressDialog dialog;
   
       @Override
       protected String doInBackground(String... params) {
           try {
               DefaultHttpClient httpClient = new DefaultHttpClient();
               HttpGet httpGet = new HttpGet(params[0]); // or HttpPost if you need
   
               ResponseHandler<String> resHandler = new BasicResponseHandler();
               response = httpClient.execute(httpGet, resHandler);
          } catch (Exception e) {
              System.out.println("E: " + e);
          }
   
          return null;
       }
   
       @Override
       protected void onPreExecute() {
           dialog = new ProgressDialog(MainActivity.this);
           dialog.setMessage("Loading...");
           dialog.setIndeterminate(true);
           dialog.setCancelable(true);
           dialog.show();
           super.onPreExecute();
       }
   
       @Override
       protected void onPostExecute(String result) {
           dialog.dismiss();
           super.onPostExecute(result);
       }
   }
   

3. To call use: new RequestTask().execute("http://192.168.0.105/index.php?pin=2&status=0")

Answer 3

The easiest way is to use volley library.

In manifest declare internet permission outside application tag : <uses-permission android:name="android.permission.INTERNET" />

In build.gradle file add this line inside dependencies: implementation 'com.android.volley:volley:1.0.0'

Create a java file named VolleySingleton and copy the file contents from the file in github just don't copy the package name.

Inside the button click add these lines:

url = "http://192.168.0.105/index.php";
StringRequest postRequest = new StringRequest(Request.Method.POST, url, 
    new Response.Listener<String>() 
    {
        @Override
        public void onResponse(String response) {
            // response
            Log.d("Response", response);
            //Do what ever you need to do with the response here.
            //If you don't need to return any response just echo OK from the php so that you become sure that the thing is working fine.
        }
    }, 
    new Response.ErrorListener() 
    {
         @Override
         public void onErrorResponse(VolleyError error) {
             // error
             Log.d("Error.Response", response);
       }
    }
) {     
    @Override
    protected Map<String, String> getParams() 
    {  
            Map<String, String>  params = new HashMap<String, String>();  
            params.put("pin", "2");  
            params.put("status", "0");

            return params;  
    }
};

VolleySingleton.getmInstance(getApplicationContext()).addToRequestQue(postRequest);

Answer 4

I have created a similar functionality

See if you find it helpful

You need to get the permission to use Internet. In manifest file, declare internet permission outside application tag : <uses-permission android:name="android.permission.INTERNET" />

Create an activity (WebViewActivity.java)

public class WebViewActivity extends AppCompatActivity {

private static final String TAG = "WebViewActivity";
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_web_view);

    Log.d(TAG, "onCreate: Started");

    Bundle extras = getIntent().getExtras();
    assert extras != null;
    String pin = extras.getString("pin"); //you can use getInt("pin") also, but afterwards in the url, it will be converted to String back, so it is not needed
    String status = extras.getString("status"); //you can use getInt("status") also, but afterwards in the url, it will be converted to String back, so it is not needed

    WebView webView = new WebView(this);
    setContentView(webView);
    WebSettings webSettings = webView.getSettings();
    webSettings.setJavaScriptEnabled(true); //This is required to enable javascript that is required by some pages
    String url = "http://192.168.0.105/index.php?pin" + pin + "&status=" + status;

    webView.loadUrl(url);

    Log.d(TAG, "url accessed: " + url);

    finish();//If you need to see the output after accessing the http page, then remove this line. Otherwise just copy as it is 
}

}

In MainActivity, just start the above created activity.

public class MainActivity extends AppCompatActivity{
    int pin = 0, status = 2;// You can modify the values according to your requirements
    //....
    //....
    button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Intent intent = new Intent(getApplicationContext(), WebViewActivity.class);
                    intent.putExtra("pin", pin);
                    intent.putExtra("status", status);
                    startActivity(intent);
                    Toast.makeText(MainActivity.this, "URL Opened and pin, status values are successfully updated", Toast.LENGTH_SHORT).show();

                }
            });
    //....
    //....
}

If you are wondering what to put in the xml file(activity_web_view.xml) Just leave as it is, I used the below code to send values just as you are trying to send.

activity_web_view.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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=".WebViewActivity" />