jdk-sandbox: comparison jdk/test/java/net/httpclient/HttpInputStreamTest.java

equal deleted inserted replaced

-:1ad58e0cbf16
+:7133f144981a
+/*
+* Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
+* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+*
+* This code is free software; you can redistribute it and/or modify it
+* under the terms of the GNU General Public License version 2 only, as
+* published by the Free Software Foundation.
+*
+* This code is distributed in the hope that it will be useful, but WITHOUT
+* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+* version 2 for more details (a copy is included in the LICENSE file that
+* accompanied this code).
+*
+* You should have received a copy of the GNU General Public License version
+* 2 along with this work; if not, write to the Free Software Foundation,
+* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+*
+* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+* or visit www.oracle.com if you need additional information or have any
+* questions.
+*/
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.net.URI;
+import jdk.incubator.http.HttpClient;
+import jdk.incubator.http.HttpHeaders;
+import jdk.incubator.http.HttpRequest;
+import jdk.incubator.http.HttpResponse;
+import java.nio.ByteBuffer;
+import java.nio.charset.Charset;
+import java.util.Locale;
+import java.util.Optional;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionStage;
+import java.util.concurrent.Flow;
+import java.util.stream.Stream;
+/*
+* @test
+* @summary An example on how to read a response body with InputStream...
+* @run main/othervm HttpInputStreamTest
+* @author daniel fuchs
+*/
+public class HttpInputStreamTest {
+public static boolean DEBUG = Boolean.getBoolean("test.debug");
+/**
+* A simple HttpResponse.BodyHandler that creates a live
+* InputStream to read the response body from the underlying ByteBuffer
+* Flow.
+* The InputStream is made immediately available for consumption, before
+* the response body is fully received.
+*/
+public static class HttpInputStreamHandler
+implements HttpResponse.BodyHandler<InputStream>    {
+public static final int MAX_BUFFERS_IN_QUEUE = 1;
+private final int maxBuffers;
+public HttpInputStreamHandler() {
+this(MAX_BUFFERS_IN_QUEUE);
+}
+public HttpInputStreamHandler(int maxBuffers) {
+this.maxBuffers = maxBuffers <= 0 ? MAX_BUFFERS_IN_QUEUE : maxBuffers;
+}
+@Override
+public synchronized HttpResponse.BodyProcessor<InputStream>
+apply(int i, HttpHeaders hh) {
+return new HttpResponseInputStream(maxBuffers);
+}
+/**
+* An InputStream built on top of the Flow API.
+*/
+private static class HttpResponseInputStream extends InputStream
+implements HttpResponse.BodyProcessor<InputStream> {
+// An immutable ByteBuffer sentinel to mark that the last byte was received.
+private static final ByteBuffer LAST = ByteBuffer.wrap(new byte[0]);
+// A queue of yet unprocessed ByteBuffers received from the flow API.
+private final BlockingQueue<ByteBuffer> buffers;
+private volatile Flow.Subscription subscription;
+private volatile boolean closed;
+private volatile Throwable failed;
+private volatile ByteBuffer current;
+HttpResponseInputStream() {
+this(MAX_BUFFERS_IN_QUEUE);
+}
+HttpResponseInputStream(int maxBuffers) {
+int capacity = maxBuffers <= 0 ? MAX_BUFFERS_IN_QUEUE : maxBuffers;
+this.buffers = new ArrayBlockingQueue<>(capacity);
+}
+@Override
+public CompletionStage<InputStream> getBody() {
+// Return the stream immediately, before the
+// response body is received.
+// This makes it possible for senAsync().get().body()
+// to complete before the response body is received.
+return CompletableFuture.completedStage(this);
+}
+// Returns the current byte buffer to read from.
+// If the current buffer has no remaining data, will take the
+// next buffer from the buffers queue, possibly blocking until
+// a new buffer is made available through the Flow API, or the
+// end of the flow is reached.
+private ByteBuffer current() throws IOException {
+while (current == null || !current.hasRemaining()) {
+// Check whether the stream is claused or exhausted
+if (closed || failed != null) {
+throw new IOException("closed", failed);
+}
+if (current == LAST) break;
+try {
+// Take a new buffer from the queue, blocking
+// if none is available yet...
+if (DEBUG) System.err.println("Taking Buffer");
+current = buffers.take();
+if (DEBUG) System.err.println("Buffer Taken");
+// Check whether some exception was encountered
+// upstream
+if (closed || failed != null) {
+throw new IOException("closed", failed);
+}
+// Check whether we're done.
+if (current == LAST) break;
+// Inform the producer that it can start sending
+// us a new buffer
+Flow.Subscription s = subscription;
+if (s != null) s.request(1);
+} catch (InterruptedException ex) {
+// continue
+}
+}
+assert current == LAST || current.hasRemaining();
+return current;
+}
+@Override
+public int read(byte[] bytes, int off, int len) throws IOException {
+// get the buffer to read from, possibly blocking if
+// none is available
+ByteBuffer buffer;
+if ((buffer = current()) == LAST) return -1;
+// don't attempt to read more than what is available
+// in the current buffer.
+int read = Math.min(buffer.remaining(), len);
+assert read > 0 && read <= buffer.remaining();
+// buffer.get() will do the boundary check for us.
+buffer.get(bytes, off, read);
+return read;
+}
+@Override
+public int read() throws IOException {
+ByteBuffer buffer;
+if ((buffer = current()) == LAST) return -1;
+return buffer.get() & 0xFF;
+}
+@Override
+public void onSubscribe(Flow.Subscription s) {
+this.subscription = s;
+s.request(Math.max(2, buffers.remainingCapacity() + 1));
+}
+@Override
+public synchronized void onNext(ByteBuffer t) {
+try {
+if (DEBUG) System.err.println("next buffer received");
+buffers.put(t);
+if (DEBUG) System.err.println("buffered offered");
+} catch (Exception ex) {
+failed = ex;
+try {
+close();
+} catch (IOException ex1) {
+// OK
+}
+}
+}
+@Override
+public void onError(Throwable thrwbl) {
+failed = thrwbl;
+}
+@Override
+public synchronized void onComplete() {
+subscription = null;
+onNext(LAST);
+}
+@Override
+public void close() throws IOException {
+synchronized (this) {
+closed = true;
+Flow.Subscription s = subscription;
+if (s != null) {
+s.cancel();
+}
+subscription = null;
+}
+super.close();
+}
+}
+}
+/**
+* Examine the response headers to figure out the charset used to
+* encode the body content.
+* If the content type is not textual, returns an empty Optional.
+* Otherwise, returns the body content's charset, defaulting to
+* ISO-8859-1 if none is explicitly specified.
+* @param headers The response headers.
+* @return The charset to use for decoding the response body, if
+*         the response body content is text/...
+*/
+public static Optional<Charset> getCharset(HttpHeaders headers) {
+Optional<String> contentType = headers.firstValue("Content-Type");
+Optional<Charset> charset = Optional.empty();
+if (contentType.isPresent()) {
+final String[] values = contentType.get().split(";");
+if (values[0].startsWith("text/")) {
+charset = Optional.of(Stream.of(values)
+.map(x -> x.toLowerCase(Locale.ROOT))
+.map(String::trim)
+.filter(x -> x.startsWith("charset="))
+.map(x -> x.substring("charset=".length()))
+.findFirst()
+.orElse("ISO-8859-1"))
+.map(Charset::forName);
+}
+}
+return charset;
+}
+public static void main(String[] args) throws Exception {
+HttpClient client = HttpClient.newHttpClient();
+HttpRequest request = HttpRequest
+.newBuilder(new URI("http://hg.openjdk.java.net/jdk9/sandbox/jdk/shortlog/http-client-branch/"))
+.GET()
+.build();
+// This example shows how to return an InputStream that can be used to
+// start reading the response body before the response is fully received.
+// In comparison, the snipet below (which uses
+// HttpResponse.BodyHandler.asString()) obviously will not return before the
+// response body is fully read:
+//
+// System.out.println(
+//    client.sendAsync(request, HttpResponse.BodyHandler.asString()).get().body());
+CompletableFuture<HttpResponse<InputStream>> handle =
+client.sendAsync(request, new HttpInputStreamHandler());
+if (DEBUG) System.err.println("Request sent");
+HttpResponse<InputStream> pending = handle.get();
+// At this point, the response headers have been received, but the
+// response body may not have arrived yet. This comes from
+// the implementation of HttpResponseInputStream::getBody above,
+// which returns an already completed completion stage, without
+// waiting for any data.
+// We can therefore access the headers - and the body, which
+// is our live InputStream, without waiting...
+HttpHeaders responseHeaders = pending.headers();
+// Get the charset declared in the response headers.
+// The optional will be empty if the content type is not
+// of type text/...
+Optional<Charset> charset = getCharset(responseHeaders);
+try (InputStream is = pending.body();
+// We assume a textual content type. Construct an InputStream
+// Reader with the appropriate Charset.
+// charset.get() will throw NPE if the content is not textual.
+Reader r = new InputStreamReader(is, charset.get())) {
+char[] buff = new char[32];
+int off=0, n=0;
+if (DEBUG) System.err.println("Start receiving response body");
+if (DEBUG) System.err.println("Charset: " + charset.get());
+// Start consuming the InputStream as the data arrives.
+// Will block until there is something to read...
+while ((n = r.read(buff, off, buff.length - off)) > 0) {
+assert (buff.length - off) > 0;
+assert n <= (buff.length - off);
+if (n == (buff.length - off)) {
+System.out.print(buff);
+off = 0;
+} else {
+off += n;
+}
+assert off < buff.length;
+}
+// last call to read may not have filled 'buff' completely.
+// flush out the remaining characters.
+assert off >= 0 && off < buff.length;
+for (int i=0; i < off; i++) {
+System.out.print(buff[i]);
+}
+// We're done!
+System.out.println("Done!");
+}
+}
+}