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 * You should have received a copy of the GNU General Public License version

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package openjdk.http.tutorial.exercise1;

import java.io.IOException;

import java.io.UncheckedIOException;

import java.net.URI;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.nio.file.StandardOpenOption;

import java.util.Arrays;

import java.util.Map;

import java.util.concurrent.CompletableFuture;

import java.util.function.Function;

import com.fasterxml.jackson.core.type.TypeReference;

import com.fasterxml.jackson.databind.ObjectMapper;

import jdk.incubator.http.HttpClient;

import jdk.incubator.http.HttpRequest;

import jdk.incubator.http.HttpResponse;

import jdk.incubator.http.HttpResponse.BodyHandler;

import static java.lang.System.out;

import static java.util.stream.Collectors.joining;

import static jdk.incubator.http.HttpClient.Version.*;

import static jdk.incubator.http.HttpResponse.BodyHandler.*;

/**

 * @author Chris Hegarty

 */

public class Retrievals {

    /**

     * Exercise 1.

     *

     * Retrieve the response status code from a request to the given

     * URI. The returned response code will be a int.

     *

     * Hint: use the discard BodyHandler since the response body is not

     * interesting.

     *

     * Hint: static imports reduce boilerplate when using BodyHandlers

     * and BodyProcessors, e.g. import static

     * jdk.incubator.http.HttpResponse.BodyHandler.discard

     */

    public static int retrieveTheStatusCode(URI uri)

        throws IOException, InterruptedException

    {

        HttpClient client = HttpClient.newBuilder().version(HTTP_1_1).build();

        HttpRequest request = HttpRequest.newBuilder(uri).GET().build();

        HttpResponse<?> response = client.send(request, discard(null));

        return response.statusCode();

    }

    /**

     * Exercise 1.

     *

     * Retrieve the response body from a given URI. Return the response

     * body as a String.

     *

     * Hint: use the asString BodyHandler to convert the HTTP response

     * body to a String.

     *

     * Hint: static imports reduce boilerplate when using BodyHandlers

     * and BodyProcessors, e.g. import static

     * jdk.incubator.http.HttpResponse.BodyHandler.asString

     */

    public static String retrieveResourceAsString(URI uri)

        throws IOException, InterruptedException

    {

        HttpClient client = HttpClient.newBuilder().version(HTTP_1_1).build();

        HttpRequest request = HttpRequest.newBuilder(uri).GET().build();

        HttpResponse<String> response = client.send(request, asString());

        return response.body();

    }

    /**

     * Exercise 2.

     *

     * Retrieve the response body from a given URI, streaming teh body

     * out to a file. Return the file's Path.

     *

     * Hint: use {@linkplain BodyHandler#asFile} to stream the HTTP

     * response body to a file.

     */

    public static Path retrieveResourceAsFile(URI uri)

        throws IOException, InterruptedException

    {

        HttpClient client = HttpClient.newBuilder().build();

        HttpRequest request = HttpRequest.newBuilder()

                .uri(uri)

                .version(HTTP_1_1)

                .GET()

                .build();

        HttpResponse<Path> response = client.send(request,

                asFile(Paths.get("retrieveResourceAsFile.txt"), StandardOpenOption.TRUNCATE_EXISTING, StandardOpenOption.WRITE));

        System.out.println("CHEGAR:   sc=" + response.statusCode());

        System.out.println("CHEGAR:   by=" + Files.readAllLines(response.body()).stream().collect(joining()));

        return response.body();

    }

    /**

     * Asserts that the response code is 200 ( OK ).

     *

     * Can be used in CompletableFuture pipelines when checking the

     * response of an {@linkplain HttpClient#sendAsync} call. For

     * example:

     *    client.sendAsync(request, bodyHandler)

     *          .thenApply(Retrievals::require200StatusCode)

     *          .thenApply(...)

     *

     */

    public static <T> HttpResponse<T> require200StatusCode(HttpResponse<T> response) {

        int sc = response.statusCode();

        if (sc != 200) {

            IOException e = new IOException("Expected 200, got: " + sc);

            throw new UncheckedIOException(e);

        }

        return response;

    }

    /**

     *  Exercise 3.

     *

     * Retrieve the response body from a given URI, using the

     * asynchronous send API, sendAsync. Return a CompletableFuture that

     * completes with the response body as a String.

     *

     * Hint: The {@linkplain CompletableFuture#thenApply(Function)}

     * method can be used to map the HttpResponse to a String.

     */

    public static CompletableFuture<String> retrieveResourceAsStringUsingAsyncAPI(URI uri) {

        return HttpClient.newHttpClient()

                .sendAsync(HttpRequest.newBuilder(uri).version(HTTP_1_1).build(), asString())  // TODO: why version needed?

                .thenApply(Retrievals::require200StatusCode)

                .thenApply(HttpResponse::body);

    }

    /**

     * Wrapper around Jackson's ObjectMapper that provides an unchecked

     * {@code readValue}, what can be used to help solve the next

     * exercise, 4.

     */

    public static class UncheckedObjectMapper extends ObjectMapper {

        /** Parses the given JSON string into a Map. */

        Map<String,String> readValue(String content) {

            try {

                return this.readValue(content, new TypeReference<>(){});

            } catch (IOException ioe) {

                throw new UncheckedIOException(ioe);

            }

        }

    }

    /**

     * Exercise 4.

     *

     * Retrieve the response body from a given URI. The response body

     * will be in the JSON format. The Jackson based UncheckedObjectMapper

     * ( above ) can be used to parse the String response body into a

     * Map.

     *

     * Hint: The asynchronous send API will allow construction of a

     * pipeline of CompletableFutures.

     *

     * Hint: The {@linkplain CompletableFuture#thenApply(Function)}

     * method can be used to map the HttpResponse to a String, and then

     * again from a Sting to a Map ( via the object mapper ).

     */

    public CompletableFuture<Map<String,String>> JSONBodyAsMap(URI uri) {

        UncheckedObjectMapper objectMapper = new UncheckedObjectMapper();

        return HttpClient.newHttpClient()

                .sendAsync(HttpRequest.newBuilder(uri).version(HTTP_1_1).build(), asString())

                .thenApply(HttpResponse::body)

                .thenApply(objectMapper::readValue);

    }

    /**

     * Post the given {@code data}, and receive the same data in

     * response. Return the response body data as a String.

     */

    public static String postData(URI uri, String data)

        throws IOException, InterruptedException

    {

        HttpClient client = HttpClient.newBuilder().build();

        HttpRequest request = HttpRequest.newBuilder()

                .uri(uri)

                .version(HTTP_1_1)

                .POST(HttpRequest.BodyProcessor.fromString(data))

                .build();

        HttpResponse<String> response = client.send(request, asString());

        return response.body();

    }

     // JSON processor

}