An efficient utility class for sending Apple push notification (Apns) over HTTP 2.0

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.mycompany</groupId>
    <artifactId>AppleNotificationH2</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <alpn-boot-version>8.1.6.v20151105</alpn-boot-version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>com.squareup.okhttp3</groupId>
            <artifactId>okhttp</artifactId>
            <version>3.4.1</version>
        </dependency>
        <dependency>
            <groupId>com.squareup.okhttp3</groupId>
            <artifactId>logging-interceptor</artifactId>
            <version>3.4.1</version>
        </dependency>
    </dependencies>
    
</project>

PushClass.java

import java.io.FileInputStream;
import java.io.IOException;
import java.security.KeyManagementException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.UnrecoverableKeyException;
import java.security.cert.CertificateException;
import java.util.Arrays;
import java.util.Collections;
import java.util.concurrent.TimeUnit;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.KeyManager;
import javax.net.ssl.KeyManagerFactory;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSession;
import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;
import okhttp3.CipherSuite;
import okhttp3.ConnectionSpec;
import okhttp3.MediaType;
import okhttp3.OkHttpClient;
import okhttp3.Protocol;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;
import okhttp3.TlsVersion;
import okhttp3.logging.HttpLoggingInterceptor;


public class PushClass {

    public static final MediaType JSON
            = MediaType.parse("application/json; charset=utf-8");
    private static final String url = "https://api.development.push.apple.com/3/device/DEVICE_ID";
    private static final String json = "{\"aps\" :{\"alert\" : \"Hello\"}}";

    public static void main(String[] args) throws IOException {
        OkHttpClient client = getOkHttpClient();
        RequestBody body = RequestBody.create(JSON, json);
        Request request = new Request.Builder()
                .url(url)
                .post(body)
                .build();
        Response response = client.newCall(request).execute();
        System.out.println("Response=>" + response.body().string());

    }

    private static final int CONNECT_TIMEOUT_MILLIS = 2 * 60; // 2 minute
    private static final int READ_TIMEOUT_MILLIS = 2 * 60; // 2 minute

    private static OkHttpClient getOkHttpClient() {
        HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
        interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
        OkHttpClient.Builder builder = new OkHttpClient.Builder()
                .protocols(Arrays.asList(Protocol.HTTP_2, Protocol.HTTP_1_1))
                .retryOnConnectionFailure(true);
        //if (BuildConfig.DEBUG) {
        try {
            ConnectionSpec spec = new ConnectionSpec.Builder(ConnectionSpec.MODERN_TLS)
                    .tlsVersions(TlsVersion.TLS_1_2, TlsVersion.TLS_1_1)
                    .cipherSuites(CipherSuite.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
                            CipherSuite.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384,
                            CipherSuite.TLS_RSA_WITH_AES_256_GCM_SHA384,
                            CipherSuite.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
                            CipherSuite.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
                            CipherSuite.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
                            CipherSuite.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256)
                    .build();
            builder.connectionSpecs(Collections.singletonList(spec));
            builder.sslSocketFactory(getSslContext().getSocketFactory(), getTrustManagers());
            builder.hostnameVerifier(hostNameVerifire());
        } catch (CertificateException | KeyStoreException | NoSuchAlgorithmException | KeyManagementException | IOException | UnrecoverableKeyException e) {
            e.printStackTrace();
        }

        builder.addNetworkInterceptor(interceptor);
        //  }
        return builder.readTimeout(READ_TIMEOUT_MILLIS, TimeUnit.SECONDS)
                .connectTimeout(CONNECT_TIMEOUT_MILLIS, TimeUnit.SECONDS)
                .build();
    }

    private static SSLContext getSslContext() throws CertificateException, KeyStoreException, IOException, NoSuchAlgorithmException, KeyManagementException, UnrecoverableKeyException {
        KeyStore clientStore = KeyStore.getInstance("PKCS12");
        clientStore.load(new FileInputStream("CERT_FILE_PATH"), "PASSWORD".toCharArray());

        KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
        kmf.init(clientStore, "PASSWORD".toCharArray());
        KeyManager[] kms = kmf.getKeyManagers();

        X509TrustManager tms = getTrustManagers();
        SSLContext sslContext;
        sslContext = SSLContext.getInstance("TLS");
        sslContext.init(kms, new TrustManager[]{tms}, new SecureRandom());
        return sslContext;

    }

    private static X509TrustManager getTrustManagers() throws KeyStoreException, IOException, NoSuchAlgorithmException, CertificateException {
        String keyStoreType = KeyStore.getDefaultType();
        KeyStore trustStore = KeyStore.getInstance(keyStoreType);
        trustStore.load(null, null);
        TrustManagerFactory tmf = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
        tmf.init((KeyStore) null);
        TrustManager[] trustManagers = tmf.getTrustManagers();
        if (trustManagers.length != 1 || !(trustManagers[0] instanceof X509TrustManager)) {
            throw new IllegalStateException("Unexpected default trust managers:"
                    + Arrays.toString(trustManagers));
        }
        return (X509TrustManager) trustManagers[0];
    }

    public static HostnameVerifier hostNameVerifire() {
        HostnameVerifier hostnameVerifier = new HostnameVerifier() {
            @Override
            public boolean verify(String hostname, SSLSession session) {
                //   Log.i(TAG, "HOST NAME " + hostname);
                HostnameVerifier hv = HttpsURLConnection.getDefaultHostnameVerifier();
                return true;
            }
        };
        return hostnameVerifier;
    }
}

if you are using net beans, add ALPN JAR in VM option by right-clicking on
project-properties-run; in VM option add -Xbootclasspath/p:ALPN_BOOT_JAR_PATH.
Make sure ALPN boot jar is loaded in vm.