Module java.net.http
Package java.net.http

Class HttpResponse.BodySubscribers

  • Enclosing interface:
    HttpResponse<T>
    public static class HttpResponse.BodySubscribers
extends Object
    Implementations of BodySubscriber that implement various useful subscribers, such as converting the response body bytes into a String, or streaming the bytes to a file.

    The following are examples of using the predefined body subscribers to convert a flow of response body data into common high-level Java objects: 

       // Streams the response body to a File
   HttpResponse<byte[]> response = client
     .send(request, responseInfo -> BodySubscribers.ofByteArray());

   // Accumulates the response body and returns it as a byte[]
   HttpResponse<byte[]> response = client
     .send(request, responseInfo -> BodySubscribers.ofByteArray());

   // Discards the response body
   HttpResponse<Void> response = client
     .send(request, responseInfo -> BodySubscribers.discarding());

   // Accumulates the response body as a String then maps it to its bytes
   HttpResponse<byte[]> response = client
     .send(request, responseInfo ->
        BodySubscribers.mapping(BodySubscribers.ofString(UTF_8), String::getBytes));
    Since:
    11

    • Method Detail

      • fromSubscriber

        public static HttpResponse.BodySubscriber<Void> fromSubscriber​(Flow.Subscriber<? super List<ByteBuffer>> subscriber)
        Returns a body subscriber that forwards all response body to the given Flow.Subscriber. The completion stage of the returned body subscriber completes after one of the given subscribers onComplete or onError has been invoked.
        API Note:
        This method can be used as an adapter between BodySubscriber and Flow.Subscriber.
        Parameters:
        subscriber - the subscriber
        Returns:
        a body subscriber

      • fromSubscriber

        public static <S extends Flow.Subscriber<? super List<ByteBuffer>>,​T> HttpResponse.BodySubscriber<T> fromSubscriber​(S subscriber,
                                                                                                                          Function<? super S,​? extends T> finisher)
        Returns a body subscriber that forwards all response body to the given Flow.Subscriber. The completion stage of the returned body subscriber completes after one of the given subscribers onComplete or onError has been invoked.

        The given finisher function is applied after the given subscriber's onComplete has been invoked. The finisher function is invoked with the given subscriber, and returns a value that is set as the response's body.

        API Note:
        This method can be used as an adapter between BodySubscriber and Flow.Subscriber.
        Type Parameters:
        S - the type of the Subscriber
        T - the type of the response body
        Parameters:
        subscriber - the subscriber
        finisher - a function to be applied after the subscriber has completed
        Returns:
        a body subscriber

      • fromLineSubscriber

        public static HttpResponse.BodySubscriber<Void> fromLineSubscriber​(Flow.Subscriber<? super String> subscriber)
        Returns a body subscriber that forwards all response body to the given Flow.Subscriber, line by line. The completion stage of the returned body subscriber completes after one of the given subscribers onComplete or onError has been invoked. Bytes are decoded using the UTF-8 charset, and lines are delimited in the manner of BufferedReader.readLine().
        API Note:
        This method can be used as an adapter between BodySubscriber and Flow.Subscriber.
        Implementation Note:
        This is equivalent to calling 
        
      fromLineSubscriber(subscriber, s -> null, StandardCharsets.UTF_8, null)
        Parameters:
        subscriber - the subscriber
        Returns:
        a body subscriber

      • fromLineSubscriber

        public static <S extends Flow.Subscriber<? super String>,​T> HttpResponse.BodySubscriber<T> fromLineSubscriber​(S subscriber,
                                                                                                                    Function<? super S,​? extends T> finisher,
                                                                                                                    Charset charset,
                                                                                                                    String lineSeparator)
        Returns a body subscriber that forwards all response body to the given Flow.Subscriber, line by line. The completion stage of the returned body subscriber completes after one of the given subscribers onComplete or onError has been invoked.

        The given finisher function is applied after the given subscriber's onComplete has been invoked. The finisher function is invoked with the given subscriber, and returns a value that is set as the response's body.

        API Note:
        This method can be used as an adapter between BodySubscriber and Flow.Subscriber.
        Type Parameters:
        S - the type of the Subscriber
        T - the type of the response body
        Parameters:
        subscriber - the subscriber
        finisher - a function to be applied after the subscriber has completed
        charset - a Charset to decode the bytes
        lineSeparator - an optional line separator: can be null, in which case lines will be delimited in the manner of BufferedReader.readLine().
        Returns:
        a body subscriber
        Throws:
        IllegalArgumentException - if the supplied lineSeparator is the empty string

      • ofString

        public static HttpResponse.BodySubscriber<String> ofString​(Charset charset)
        Returns a body subscriber which stores the response body as a String converted using the given Charset.

        The HttpResponse using this subscriber is available after the entire response has been read.

        Parameters:
        charset - the character set to convert the String with
        Returns:
        a body subscriber

      • ofByteArray

        public static HttpResponse.BodySubscriber<byte[]> ofByteArray()
        Returns a BodySubscriber which stores the response body as a byte array.

        The HttpResponse using this subscriber is available after the entire response has been read.

        Returns:
        a body subscriber

      • ofFile

        public static HttpResponse.BodySubscriber<Path> ofFile​(Path file,
                                                       OpenOption... openOptions)
        Returns a BodySubscriber which stores the response body in a file opened with the given options and name. The file will be opened with the given options using FileChannel.open just before the body is read. Any exception thrown will be returned or thrown from HttpClient::send or HttpClient::sendAsync as appropriate.

        The HttpResponse using this subscriber is available after the entire response has been read.

        Security manager permission checks are performed in this factory method, when the BodySubscriber is created. Care must be taken that the BodyHandler is not shared with untrusted code.

        Parameters:
        file - the file to store the body in
        openOptions - the list of options to open the file with
        Returns:
        a body subscriber
        Throws:
        IllegalArgumentException - if an invalid set of open options are specified
        SecurityException - if a security manager has been installed and it denies write access to the file

      • ofFile

        public static HttpResponse.BodySubscriber<Path> ofFile​(Path file)
        Returns a BodySubscriber which stores the response body in a file opened with the given name.

        Equivalent to: ofFile(file, CREATE, WRITE)

        Security manager permission checks are performed in this factory method, when the BodySubscriber is created. Care must be taken that the BodyHandler is not shared with untrusted code.

        Parameters:
        file - the file to store the body in
        Returns:
        a body subscriber
        Throws:
        SecurityException - if a security manager has been installed and it denies write access to the file

      • ofByteArrayConsumer

        public static HttpResponse.BodySubscriber<Void> ofByteArrayConsumer​(Consumer<Optional<byte[]>> consumer)
        Returns a BodySubscriber which provides the incoming body data to the provided Consumer of Optional<byte[]>. Each call to Consumer.accept() will contain a non empty Optional, except for the final invocation after all body data has been read, when the Optional will be empty.

        The HttpResponse using this subscriber is available after the entire response has been read.

        API Note:
        This subscriber is not flow controlled. Therefore, the supplied consumer must be able to process whatever amount of data is delivered in a timely fashion.
        Parameters:
        consumer - a Consumer of byte arrays
        Returns:
        a BodySubscriber

      • ofInputStream

        public static HttpResponse.BodySubscriber<InputStream> ofInputStream()
        Returns a BodySubscriber which streams the response body as an InputStream.

        The HttpResponse using this subscriber is available immediately after the response headers have been read, without requiring to wait for the entire body to be processed. The response body can then be read directly from the InputStream.

        API Note:
        To ensure that all resources associated with the corresponding exchange are properly released the caller must ensure to either read all bytes until EOF is reached, or call InputStream.close() if it is unable or unwilling to do so. Calling close before exhausting the stream may cause the underlying HTTP connection to be closed and prevent it from being reused for subsequent operations.
        Returns:
        a body subscriber that streams the response body as an InputStream.

      • ofLines

        public static HttpResponse.BodySubscriber<Stream<String>> ofLines​(Charset charset)
        Returns a BodySubscriber which streams the response body as a Stream<String>, where each string in the stream corresponds to a line as defined by BufferedReader.lines().

        The HttpResponse using this subscriber is available immediately after the response headers have been read, without requiring to wait for the entire body to be processed. The response body can then be read directly from the Stream.

        API Note:
        To ensure that all resources associated with the corresponding exchange are properly released the caller must ensure to either read all lines until the stream is exhausted, or call BaseStream.close() if it is unable or unwilling to do so. Calling close before exhausting the stream may cause the underlying HTTP connection to be closed and prevent it from being reused for subsequent operations.
        Parameters:
        charset - the character set to use when converting bytes to characters
        Returns:
        a body subscriber that streams the response body as a Stream<String>.
        See Also:
        BufferedReader.lines()

      • ofPublisher

        public static HttpResponse.BodySubscriber<Flow.Publisher<List<ByteBuffer>>> ofPublisher()
        Returns a response subscriber which publishes the response body through a Publisher<List<ByteBuffer>>.

        The HttpResponse using this subscriber is available immediately after the response headers have been read, without requiring to wait for the entire body to be processed. The response body bytes can then be obtained by subscribing to the publisher returned by the HttpResponse body method.

        The publisher returned by the body method can be subscribed to only once. The first subscriber will receive the body response bytes if successfully subscribed, or will cause the subscription to be cancelled otherwise. If more subscriptions are attempted, the subsequent subscribers will be immediately subscribed with an empty subscription and their onError method will be invoked with an IllegalStateException.

        API Note:
        To ensure that all resources associated with the corresponding exchange are properly released the caller must ensure that the provided publisher is subscribed once, and either requests all bytes until onComplete or onError are invoked, or cancel the provided subscription if it is unable or unwilling to do so. Note that depending on the actual HTTP protocol version used for the exchange, cancelling the subscription instead of exhausting the flow may cause the underlying HTTP connection to be closed and prevent it from being reused for subsequent operations.
        Returns:
        A BodySubscriber which publishes the response body through a Publisher<List<ByteBuffer>>.

      • replacing

        public static <U> HttpResponse.BodySubscriber<U> replacing​(U value)
        Returns a response subscriber which discards the response body. The supplied value is the value that will be returned from HttpResponse.body().
        Type Parameters:
        U - the type of the response body
        Parameters:
        value - the value to return from HttpResponse.body(), may be null
        Returns:
        a BodySubscriber

      • discarding

        public static HttpResponse.BodySubscriber<Void> discarding()
        Returns a response subscriber which discards the response body.
        Returns:
        a response body subscriber

      • buffering

        public static <T> HttpResponse.BodySubscriber<T> buffering​(HttpResponse.BodySubscriber<T> downstream,
                                                           int bufferSize)
        Returns a BodySubscriber which buffers data before delivering it to the given downstream subscriber. The subscriber guarantees to deliver buffersize bytes of data to each invocation of the downstream's onNext method, except for the final invocation, just before onComplete is invoked. The final invocation of onNext may contain fewer than bufferSize bytes.

        The returned subscriber delegates its getBody() method to the downstream subscriber.

        Type Parameters:
        T - the type of the response body
        Parameters:
        downstream - the downstream subscriber
        bufferSize - the buffer size
        Returns:
        a buffering body subscriber
        Throws:
        IllegalArgumentException - if bufferSize <= 0

      • mapping

        public static <T,​U> HttpResponse.BodySubscriber<U> mapping​(HttpResponse.BodySubscriber<T> upstream,
                                                                 Function<? super T,​? extends U> mapper)
        Returns a BodySubscriber whose response body value is that of the result of applying the given function to the body object of the given upstream BodySubscriber.

        The mapping function is executed using the client's executor, and can therefore be used to map any response body type, including blocking InputStream, as shown in the following example which uses a well-known JSON parser to convert an InputStream into any annotated Java type.

        For example: 

          public static <W> BodySubscriber<W> asJSON(Class<W> targetType) {
     BodySubscriber<InputStream> upstream = BodySubscribers.ofInputStream();

     BodySubscriber<W> downstream = BodySubscribers.mapping(
           upstream,
           (InputStream is) -> {
               try (InputStream stream = is) {
                   ObjectMapper objectMapper = new ObjectMapper();
                   return objectMapper.readValue(stream, targetType);
               } catch (IOException e) {
                   throw new UncheckedIOException(e);
               }
           });
    return downstream;
 }
        Type Parameters:
        T - the upstream body type
        U - the type of the body subscriber returned
        Parameters:
        upstream - the body subscriber to be mapped
        mapper - the mapping function
        Returns:
        a mapping body subscriber