Making Rest Request with Android Volley

Step 1) add dependacy for Android Volley in app gradle file dependancy section

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:27.1.1'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    compile 'com.android.volley:volley:1.1.1'
}

Step 2) Add INTERNET Permission to android Manifes file: AndroidManifest.xml

Step 3) Add code for Volley

public class MainActivity extends AppCompatActivity {
    private ProgressBar pb;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        final TextView txtrs = findViewById(R.id.txtrs);

        Button btnControl = findViewById(R.id.btnControl);
        final RequestQueue qu =Volley.newRequestQueue(this);
        final String url = "https://www.iocare.in/discovery";
        pb = findViewById(R.id.progressBar);

        pb.setVisibility(View.GONE);

        btnControl.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                pb.setVisibility(View.VISIBLE);
                StringRequest stringRequest = new StringRequest(Request.Method.GET, url,
                        new Response.Listener() {
                            @Override
                            public void onResponse(String response) {
                                // Display the first 500 characters of the response string.
                                pb.setVisibility(View.GONE);
                                txtrs.setText("Response is: "+ response.substring(0,500));
                            }
                        }, new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        txtrs.setText("That didn't work!");
                    }
                });

// Add the request to the RequestQueue.
                qu.add(stringRequest);
            }
        });

        btnActivity.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intentActivity = new Intent(getApplicationContext(),ActivityData.class);
                intentActivity.putExtra("in.iocare.sqlitetest.data","Welcome to Data");
                startActivity(intentActivity);
            }
        });
        btnDatabase.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String url = "https://www.iocare.in";
                Uri webAddress = Uri.parse(url);
                Intent browserIntent = new Intent(Intent.ACTION_VIEW,webAddress);
                if(browserIntent.resolveActivity(getPackageManager())!=null){
                    startActivity(browserIntent);
                }

            }
        });
    }
}

 
Step 4:

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>

const char *ssid = "iocare";
const char *password = "iocare2018";

ESP8266WebServer server(80);

const int led1 = 5;
const int led2 = 4;

void handleControl() {
int lightno = server.arg("lightno").toInt();
int state = server.arg("state").toInt();
if (lightno == 1) {
if (state == 1) {
digitalWrite(led1, HIGH);
server.send(200, "text/html", "LED1 ON");
} else {
digitalWrite(led1, LOW);
server.send(200, "text/html", "LED1 OFF");
}
}

if (lightno == 2) {
if (state == 1) {
digitalWrite(led2, HIGH);
server.send(200, "text/html", "LED2 ON");
} else {
digitalWrite(led2, LOW);
server.send(200, "text/html", "LED2 OFF");
}
}

}

void handleNotFound() {

String message = "File Not Found\n\n";
message += "URI: ";
message += server.uri();
message += "\nMethod: ";
message += (server.method() == HTTP_GET) ? "GET" : "POST";
message += "\nArguments: ";
message += server.args();
message += "\n";

for (uint8_t i = 0; i < server.args(); i++) {
message += " " + server.argName(i) + ": " + server.arg(i) + "\n";
}

server.send(404, "text/plain", message);

}

void setup(void) {
pinMode(led1, OUTPUT);
pinMode(led2, OUTPUT);
digitalWrite(led1, 0);
digitalWrite(led2, 0);
Serial.begin(115200);

WiFi.mode(WIFI_STA);
WiFi.begin(ssid, password);
Serial.println("");

// Wait for connection
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}

Serial.println("");
Serial.print("Connected to ");
Serial.println(ssid);
Serial.print("IP address: ");
Serial.println(WiFi.localIP());

if (MDNS.begin("esp8266")) {
Serial.println("MDNS responder started");
}

server.on("/control", handleControl);

server.on("/inline", []() {
server.send(200, "text/plain", "this works as well");
});

server.onNotFound(handleNotFound);
server.begin();
Serial.println("HTTP server started");
}

void loop(void) {
server.handleClient();
}