Android/HttpRequest通信/okhttp3

必須

Android 2.3以降

AndroidManifest.xml

<uses-permission android:name="android.permission.INTERNET" />

インストール

app/build.gradle

dependencies {
  implementation 'com.squareup.okhttp3:okhttp:3.7.0'
}

参考：https://qiita.com/naoi/items/8d493f00b0bbbf8a666c

同期処理

import okhttp3.Call;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import okhttp3.ResponseBody;
String url = "https://api.github.com/feeds";
OkHttpClient client = new OkHttpClient();
try {
    Request request = new Request.Builder().url(url).build();
    Call call = client.newCall(request);
    Response response = call.execute();
    ResponseBody body = response.body();
    String res = body.string();
    Log.i("okhttp3", "res=" + res);
} catch (IOException e) {
}

同期処理なので、NetworkOnMainThreadExceptionエラーが出る場合はAcyncTask側で処理する必要がある

非同期処理

import android.os.Handler;
import android.os.Looper;
import android.util.Log;
import java.io.IOException;
import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import okhttp3.ResponseBody;
String url = "https://api.github.com/feeds";
OkHttpClient client = new OkHttpClient();
// RequestBody requestbodey = new FormBody.Builder()
//        .build();
Request request = new Request.Builder()
         .url(url)
         //.post(requestbodey)
         .get()
         .build();
client.newCall(request).enqueue(new Callback() {
     final Handler mainHandler = new Handler(Looper.getMainLooper());
     @Override
     public void onFailure(Call call, IOException e) {
         e.printStackTrace();
     }
     @Override
     public void onResponse(Call call, Response response) throws IOException {
         String result = response.body().string();
         String callString = call.toString();
         Log.i("okhttp3", "res=" + result);
     }
});

非同期なのでメインスレッド側に記述できる

参考：http://nandarou.hateblo.jp/entry/2017/05/23/180728

javax.net.ssl.SSLHandshakeException: javax.net.ssl.SSLProtocolException: SSL handshake aborted: エラーが起こる場合

Android 4.4でエラーが起こるらしい(Android4.1.1で自分はこのエラーを確認した)

List<CipherSuite> cipherSuites = new ArrayList<>();
       cipherSuites.addAll(ConnectionSpec.MODERN_TLS.cipherSuites());
       cipherSuites.add(CipherSuite.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA);
       cipherSuites.add(CipherSuite.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA);

ConnectionSpec legacyTls = new ConnectionSpec.Builder(ConnectionSpec.MODERN_TLS)
               .cipherSuites(cipherSuites.toArray(new CipherSuite[0]))
               .build();
OkHttpClient client = new OkHttpClient.Builder()
               .connectionSpecs(Arrays.asList(legacyTls, ConnectionSpec.CLEARTEXT))
               .build();

参考：https://github.com/square/okhttp/issues/4053