Allow setting a custom EventListener in ApiClientBuilder

clients/line-bot-client-base/src/main/java/com/linecorp/bot/client/base/ApiClientBuilder.java

@@ -30,13 +30,16 @@
 import com.fasterxml.jackson.databind.DeserializationFeature;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
+import com.linecorp.bot.client.base.http.EventListenerAdapter;
 import com.linecorp.bot.client.base.http.HttpAuthenticator;
 import com.linecorp.bot.client.base.http.HttpChain;
+import com.linecorp.bot.client.base.http.HttpEventListener;
 import com.linecorp.bot.client.base.http.HttpInterceptor;
 import com.linecorp.bot.client.base.http.HttpResponse;
 import com.linecorp.bot.jackson.ModelObjectMapper;
 
 import okhttp3.Dispatcher;
+import okhttp3.EventListener;
 import okhttp3.Interceptor;
 import okhttp3.OkHttpClient;
 import okhttp3.Request;
@@ -89,6 +92,13 @@ public ApiClientBuilder(URI apiEndPoint, Class<T> clientClass, ExceptionBuilder
      */
     private List<Interceptor> additionalInterceptors = new ArrayList<>();
 
+    /**
+     * Custom EventListener
+     *
+     * <p>You can add your own EventListener.
+     */
+    private EventListener eventListener;
+
     private Proxy proxy;
 
     private HttpAuthenticator proxyAuthenticator;
@@ -141,6 +151,11 @@ public ApiClientBuilder<T> addInterceptor(HttpInterceptor interceptor) {
         return this;
     }
 
+    public ApiClientBuilder<T> setEventListener(HttpEventListener httpEventListener) {
+        this.eventListener = new EventListenerAdapter(httpEventListener);
+        return this;
+    }
+
     /**
      * The maximum number of requests to execute concurrently.
      * Default: 64
@@ -230,6 +245,10 @@ public T build() {
             }
         });
 
+        if (this.eventListener != null) {
+            okHttpClientBuilder.eventListener(this.eventListener);
+        }
+
         if (this.proxy != null) {
             okHttpClientBuilder.proxy(this.proxy);
         }
@@ -262,6 +281,7 @@ public String toString() {
                 + ", readTimeout=" + readTimeout
                 + ", writeTimeout=" + writeTimeout
                 + ", additionalInterceptors=" + additionalInterceptors
+                + ", eventListener=" + eventListener
                 + ", maxRequests=" + maxRequests
                 + ", maxRequestsPerHost=" + maxRequestsPerHost
                 + '}';

clients/line-bot-client-base/src/main/java/com/linecorp/bot/client/base/http/EventListenerAdapter.java

@@ -0,0 +1,185 @@
+/*
+ * Copyright 2025 LINE Corporation
+ *
+ * LINE Corporation licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
+package com.linecorp.bot.client.base.http;
+
+import java.io.IOException;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.Proxy;
+import java.util.List;
+
+import okhttp3.Call;
+import okhttp3.Connection;
+import okhttp3.EventListener;
+import okhttp3.Handshake;
+import okhttp3.HttpUrl;
+import okhttp3.Protocol;
+import okhttp3.Request;
+import okhttp3.Response;
+
+public class EventListenerAdapter extends EventListener {
+    private final HttpEventListener httpEventListener;
+
+    public EventListenerAdapter(HttpEventListener httpEventListener) {
+        this.httpEventListener = httpEventListener;
+    }
+
+    @Override
+    public void callStart(Call call) {
+        httpEventListener.callStart(new HttpCall(call));
+    }
+
+    @Override
+    public void proxySelectStart(Call call, HttpUrl url) {
+        httpEventListener.proxySelectStart(new HttpCall(call), new HttpEndpoint(url));
+    }
+
+    @Override
+    public void proxySelectEnd(Call call, HttpUrl url, List<Proxy> proxies) {
+        httpEventListener.proxySelectEnd(new HttpCall(call), new HttpEndpoint(url), proxies);
+    }
+
+    @Override
+    public void dnsStart(Call call, String domainName) {
+        httpEventListener.dnsStart(new HttpCall(call), domainName);
+    }
+
+    @Override
+    public void dnsEnd(Call call, String domainName, List<InetAddress> inetAddressList) {
+        httpEventListener.dnsEnd(new HttpCall(call), domainName, inetAddressList);
+    }
+
+    @Override
+    public void connectStart(Call call, InetSocketAddress inetSocketAddress, Proxy proxy) {
+        httpEventListener.connectStart(new HttpCall(call), inetSocketAddress, proxy);
+    }
+
+    @Override
+    public void secureConnectStart(Call call) {
+        httpEventListener.secureConnectStart(new HttpCall(call));
+    }
+
+    @Override
+    public void secureConnectEnd(Call call, Handshake handshake) {
+        httpEventListener.secureConnectEnd(new HttpCall(call), handshake != null ? new TlsHandshake(handshake) : null);
+    }
+
+    @Override
+    public void connectEnd(Call call, InetSocketAddress inetSocketAddress, Proxy proxy, Protocol protocol) {
+        httpEventListener.connectEnd(new HttpCall(call), inetSocketAddress, proxy, protocol != null ? new HttpProtocol(protocol) : null);
+    }
+
+    @Override
+    public void connectFailed(Call call, InetSocketAddress inetSocketAddress, Proxy proxy, Protocol protocol, IOException ioe) {
+        httpEventListener.connectFailed(new HttpCall(call), inetSocketAddress, proxy, protocol != null ? new HttpProtocol(protocol) : null, ioe);
+    }
+
+    @Override
+    public void connectionAcquired(Call call, Connection connection) {
+        httpEventListener.connectionAcquired(new HttpCall(call), new HttpConnection(connection));
+    }
+
+    @Override
+    public void connectionReleased(Call call, Connection connection) {
+        httpEventListener.connectionReleased(new HttpCall(call), new HttpConnection(connection));
+    }
+
+    @Override
+    public void requestHeadersStart(Call call) {
+        httpEventListener.requestHeadersStart(new HttpCall(call));
+    }
+
+    @Override
+    public void requestHeadersEnd(Call call, Request request) {
+        httpEventListener.requestHeadersEnd(new HttpCall(call), new HttpRequest(request));
+    }
+
+    @Override
+    public void requestBodyStart(Call call) {
+        httpEventListener.requestBodyStart(new HttpCall(call));
+    }
+
+    @Override
+    public void requestBodyEnd(Call call, long byteCount) {
+        httpEventListener.requestBodyEnd(new HttpCall(call), byteCount);
+    }
+
+    @Override
+    public void requestFailed(Call call, IOException ioe) {
+        httpEventListener.requestFailed(new HttpCall(call), ioe);
+    }
+
+    @Override
+    public void responseHeadersStart(Call call) {
+        httpEventListener.responseHeadersStart(new HttpCall(call));
+    }
+
+    @Override
+    public void responseHeadersEnd(Call call, Response response) {
+        httpEventListener.responseHeadersEnd(new HttpCall(call), new HttpResponse(response));
+    }
+
+    @Override
+    public void responseBodyStart(Call call) {
+        httpEventListener.responseBodyStart(new HttpCall(call));
+    }
+
+    @Override
+    public void responseBodyEnd(Call call, long byteCount) {
+        httpEventListener.responseBodyEnd(new HttpCall(call), byteCount);
+    }
+
+    @Override
+    public void responseFailed(Call call, IOException ioe) {
+        httpEventListener.responseFailed(new HttpCall(call), ioe);
+    }
+
+    @Override
+    public void callEnd(Call call) {
+        httpEventListener.callEnd(new HttpCall(call));
+    }
+
+    @Override
+    public void callFailed(Call call, IOException ioe) {
+        httpEventListener.callFailed(new HttpCall(call), ioe);
+    }
+
+    @Override
+    public void canceled(Call call) {
+        httpEventListener.canceled(new HttpCall(call));
+    }
+
+    @Override
+    public void satisfactionFailure(Call call, Response response) {
+        httpEventListener.satisfactionFailure(new HttpCall(call), new HttpResponse(response));
+    }
+
+    @Override
+    public void cacheHit(Call call, Response response) {
+        httpEventListener.cacheHit(new HttpCall(call), new HttpResponse(response));
+    }
+
+    @Override
+    public void cacheMiss(Call call) {
+        httpEventListener.cacheMiss(new HttpCall(call));
+    }
+
+    @Override
+    public void cacheConditionalHit(Call call, Response cachedResponse) {
+        httpEventListener.cacheConditionalHit(new HttpCall(call), new HttpResponse(cachedResponse));
+    }
+}

clients/line-bot-client-base/src/main/java/com/linecorp/bot/client/base/http/HttpCall.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2025 LINE Corporation
+ *
+ * LINE Corporation licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
+package com.linecorp.bot.client.base.http;
+
+import okhttp3.Call;
+
+public class HttpCall {
+    private final Call call;
+
+    public HttpCall(Call call) {
+        this.call = call;
+    }
+
+    public HttpRequest request() {
+        return new HttpRequest(call.request());
+    }
+
+    public Call toOkHttpCall() {
+        return call;
+    }
+}

clients/line-bot-client-base/src/main/java/com/linecorp/bot/client/base/http/HttpConnection.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2025 LINE Corporation
+ *
+ * LINE Corporation licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
+package com.linecorp.bot.client.base.http;
+
+import okhttp3.Connection;
+
+public class HttpConnection {
+    private final Connection connection;
+
+    public HttpConnection(Connection connection) {
+        this.connection = connection;
+    }
+
+    public Connection toOkHttpConnection() {
+        return connection;
+    }
+}

clients/line-bot-client-base/src/main/java/com/linecorp/bot/client/base/http/HttpEndpoint.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2025 LINE Corporation
+ *
+ * LINE Corporation licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
+package com.linecorp.bot.client.base.http;
+
+import okhttp3.HttpUrl;
+
+public class HttpEndpoint {
+    private final HttpUrl httpUrl;
+
+    public HttpEndpoint(HttpUrl httpUrl) {
+        this.httpUrl = httpUrl;
+    }
+
+    public HttpUrl toOkHttpUrl() {
+        return httpUrl;
+    }
+}