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* version 2 for more details (a copy is included in the LICENSE file that
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*
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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
}