httpclient5/src/test/java/org/apache/hc/client5/http/examples/ClientInterceptors.java

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 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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
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 * 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.
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package org.apache.hc.client5.http.examples;

import java.io.IOException;
import java.util.concurrent.atomic.AtomicLong;

import org.apache.hc.client5.http.classic.methods.HttpGet;
import org.apache.hc.client5.http.impl.ChainElement;
import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import org.apache.hc.core5.http.ClassicHttpResponse;
import org.apache.hc.core5.http.ContentType;
import org.apache.hc.core5.http.EntityDetails;
import org.apache.hc.core5.http.Header;
import org.apache.hc.core5.http.HttpException;
import org.apache.hc.core5.http.HttpRequest;
import org.apache.hc.core5.http.HttpRequestInterceptor;
import org.apache.hc.core5.http.HttpStatus;
import org.apache.hc.core5.http.io.entity.EntityUtils;
import org.apache.hc.core5.http.io.entity.StringEntity;
import org.apache.hc.core5.http.message.BasicClassicHttpResponse;
import org.apache.hc.core5.http.message.StatusLine;
import org.apache.hc.core5.http.protocol.HttpContext;

/**
 * This example demonstrates how to insert custom request interceptor and an execution interceptor
 * to the request execution chain.
 */
public class ClientInterceptors {

    public static void main(final String[] args) throws Exception {
        try (final CloseableHttpClient httpclient = HttpClients.custom()

                // Add a simple request ID to each outgoing request

                .addRequestInterceptorFirst(new HttpRequestInterceptor() {

                    private final AtomicLong count = new AtomicLong(0);

                    @Override
                    public void process(
                            final HttpRequest request,
                            final EntityDetails entity,
                            final HttpContext context) throws HttpException, IOException {
                        request.setHeader("request-id", Long.toString(count.incrementAndGet()));
                    }
                })

                // Simulate a 404 response for some requests without passing the message down to the backend

                .addExecInterceptorAfter(ChainElement.PROTOCOL.name(), "custom", (request, scope, chain) -> {

                    final Header idHeader = request.getFirstHeader("request-id");
                    if (idHeader != null && "13".equalsIgnoreCase(idHeader.getValue())) {
                        final ClassicHttpResponse response = new BasicClassicHttpResponse(HttpStatus.SC_NOT_FOUND, "Oppsie");
                        response.setEntity(new StringEntity("bad luck", ContentType.TEXT_PLAIN));
                        return response;
                    } else {
                        return chain.proceed(request, scope);
                    }
                })
                .build()) {

            for (int i = 0; i < 20; i++) {
                final HttpGet httpget = new HttpGet("http://httpbin.org/get");

                System.out.println("Executing request " + httpget.getMethod() + " " + httpget.getUri());

                httpclient.execute(httpget, response -> {
                    System.out.println("----------------------------------------");
                    System.out.println(httpget + "->" + new StatusLine(response));
                    EntityUtils.consume(response.getEntity());
                    return null;
                });
            }
        }
    }

}