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/OpenJDK 21

Class HttpResponse.BodyHandlers

java.lang.Object
java.net.http.HttpResponse.BodyHandlers
Enclosing interface:
HttpResponse<T>
public static class HttpResponse.BodyHandlers extends Object
Implementations of BodyHandler that implement various useful handlers, such as handling the response body as a String, or streaming the response body to a file.

These implementations do not examine the status code, meaning the body is always accepted. They typically return an equivalently named BodySubscriber. Alternatively, a custom handler can be used to examine the status code and headers, and return a different body subscriber, of the same type, as appropriate.

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

// Receives the response body as a String
HttpResponse<String> response = client
  .send(request, BodyHandlers.ofString());
// Receives the response body as a file
HttpResponse<Path> response = client
  .send(request, BodyHandlers.ofFile(Paths.get("example.html")));
// Receives the response body as an InputStream
HttpResponse<InputStream> response = client
  .send(request, BodyHandlers.ofInputStream());
// Discards the response body
HttpResponse<Void> response = client
  .send(request, BodyHandlers.discarding());
Since:
11

Method Summary

Modifier and Type Method Description
static <T> HttpResponse.BodyHandler<T> buffering(HttpResponse.BodyHandler<T> downstreamHandler, int bufferSize)
Returns a BodyHandler which, when invoked, returns a buffering BodySubscriber that buffers data before delivering it to the downstream subscriber.
static HttpResponse.BodyHandler<Void> discarding()
Returns a response body handler that discards the response body.
static HttpResponse.BodyHandler<Void> fromLineSubscriber(Flow.Subscriber<? super String> subscriber)
Returns a response body handler that returns a BodySubscriber<Void> obtained from BodySubscribers.fromLineSubscriber(subscriber, s -> null, charset, null), with the given subscriber.
static <S extends Flow.Subscriber<? super String>, T>
HttpResponse.BodyHandler<T>		 fromLineSubscriber(S subscriber, Function<? super S,? extends T> finisher, String lineSeparator)
Returns a response body handler that returns a BodySubscriber<T> obtained from BodySubscribers.fromLineSubscriber(subscriber, finisher, charset, lineSeparator), with the given subscriber, finisher function, and line separator.
static HttpResponse.BodyHandler<Void> fromSubscriber(Flow.Subscriber<? super List<ByteBuffer>> subscriber)
Returns a response body handler that returns a BodySubscriber<Void> obtained from HttpResponse.BodySubscribers.fromSubscriber(Subscriber), with the given subscriber.
static <S extends Flow.Subscriber<? super List<ByteBuffer>>, T>
HttpResponse.BodyHandler<T>		 fromSubscriber(S subscriber, Function<? super S,? extends T> finisher)
Returns a response body handler that returns a BodySubscriber<T> obtained from HttpResponse.BodySubscribers.fromSubscriber(Subscriber, Function), with the given subscriber and finisher function.
static HttpResponse.BodyHandler<byte[]> ofByteArray()
Returns a BodyHandler<byte[]> that returns a BodySubscriber<byte[]> obtained from BodySubscribers.ofByteArray().
static HttpResponse.BodyHandler<Void> ofByteArrayConsumer(Consumer<Optional<byte[]>> consumer)
Returns a BodyHandler<Void> that returns a BodySubscriber<Void> obtained from BodySubscribers.ofByteArrayConsumer(Consumer).
static HttpResponse.BodyHandler<Path> ofFile(Path file)
Returns a BodyHandler<Path> that returns a BodySubscriber<Path>.
static HttpResponse.BodyHandler<Path> ofFile(Path file, OpenOption... openOptions)
Returns a BodyHandler<Path> that returns a BodySubscriber<Path> obtained from BodySubscribers.ofFile(Path,OpenOption...).
static HttpResponse.BodyHandler<Path> ofFileDownload(Path directory, OpenOption... openOptions)
Returns a BodyHandler<Path> that returns a BodySubscriber<Path> where the download directory is specified, but the filename is obtained from the Content-Disposition response header.
static HttpResponse.BodyHandler<InputStream> ofInputStream()
Returns a BodyHandler<InputStream> that returns a BodySubscriber<InputStream> obtained from BodySubscribers.ofInputStream.
static HttpResponse.BodyHandler<Stream<String>> ofLines()
Returns a BodyHandler<Stream<String>> that returns a BodySubscriber<Stream<String>> obtained from BodySubscribers.ofLines(charset).
static HttpResponse.BodyHandler<Flow.Publisher<List<ByteBuffer>>> ofPublisher()
Returns a BodyHandler<Publisher<List<ByteBuffer>>> that creates a BodySubscriber<Publisher<List<ByteBuffer>>> obtained from BodySubscribers.ofPublisher().
static HttpResponse.BodyHandler<String> ofString()
Returns a BodyHandler<String> that returns a BodySubscriber<String> obtained from BodySubscribers.ofString(Charset).
static HttpResponse.BodyHandler<String> ofString(Charset charset)
Returns a BodyHandler<String> that returns a BodySubscriber<String> obtained from BodySubscribers.ofString(Charset).
static <U> HttpResponse.BodyHandler<U> replacing(U value)
Returns a response body handler that returns the given replacement value, after discarding the response body.

Methods declared in class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

fromSubscriber

public static HttpResponse.BodyHandler<Void> fromSubscriber(Flow.Subscriber<? super List<ByteBuffer>> subscriber)
Returns a response body handler that returns a BodySubscriber<Void> obtained from HttpResponse.BodySubscribers.fromSubscriber(Subscriber), with the given subscriber.

The response body is not available through this, or the HttpResponse API, but instead all response body is forwarded to the given subscriber, which should make it available, if appropriate, through some other mechanism, e.g. an entry in a database, etc.

API Note:
This method can be used as an adapter between BodySubscriber and Flow.Subscriber.

For example: 

TextSubscriber subscriber = new TextSubscriber();
HttpResponse<Void> response = client.sendAsync(request,
    BodyHandlers.fromSubscriber(subscriber)).join();
System.out.println(response.statusCode());
Parameters:
subscriber - the subscriber
Returns:
a response body handler

fromSubscriber

public static <S extends Flow.Subscriber<? super List<ByteBuffer>>, T> HttpResponse.BodyHandler<T> fromSubscriber(S subscriber, Function<? super S,? extends T> finisher)
Returns a response body handler that returns a BodySubscriber<T> obtained from HttpResponse.BodySubscribers.fromSubscriber(Subscriber, Function), with the given subscriber and finisher function.

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.

For example: 

TextSubscriber subscriber = ...;  // accumulates bytes and transforms them into a String
HttpResponse<String> response = client.sendAsync(request,
    BodyHandlers.fromSubscriber(subscriber, TextSubscriber::getTextResult)).join();
String text = response.body();
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 response body handler

fromLineSubscriber

public static HttpResponse.BodyHandler<Void> fromLineSubscriber(Flow.Subscriber<? super String> subscriber)
Returns a response body handler that returns a BodySubscriber<Void> obtained from BodySubscribers.fromLineSubscriber(subscriber, s -> null, charset, null), with the given subscriber. The charset used to decode the response body bytes is obtained from the HTTP response headers as specified by ofString(), and lines are delimited in the manner of BufferedReader.readLine().

The response body is not available through this, or the HttpResponse API, but instead all response body is forwarded to the given subscriber, which should make it available, if appropriate, through some other mechanism, e.g. an entry in a database, etc.

API Note:
This method can be used as an adapter between a BodySubscriber and a text based Flow.Subscriber that parses text line by line.

For example: 

// A PrintSubscriber that implements Flow.Subscriber<String>
// and print lines received by onNext() on System.out
PrintSubscriber subscriber = new PrintSubscriber(System.out);
client.sendAsync(request, BodyHandlers.fromLineSubscriber(subscriber))
    .thenApply(HttpResponse::statusCode)
    .thenAccept((status) -> {
        if (status != 200) {
            System.err.printf("ERROR: %d status received%n", status);
        }
    });
Parameters:
subscriber - the subscriber
Returns:
a response body handler

fromLineSubscriber

public static <S extends Flow.Subscriber<? super String>, T> HttpResponse.BodyHandler<T> fromLineSubscriber(S subscriber, Function<? super S,? extends T> finisher, String lineSeparator)
Returns a response body handler that returns a BodySubscriber<T> obtained from BodySubscribers.fromLineSubscriber(subscriber, finisher, charset, lineSeparator), with the given subscriber, finisher function, and line separator. The charset used to decode the response body bytes is obtained from the HTTP response headers as specified by ofString().

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 a BodySubscriber and a text based Flow.Subscriber that parses text line by line.

For example: 

// A LineParserSubscriber that implements Flow.Subscriber<String>
// and accumulates lines that match a particular pattern
Pattern pattern = ...;
LineParserSubscriber subscriber = new LineParserSubscriber(pattern);
HttpResponse<List<String>> response = client.send(request,
    BodyHandlers.fromLineSubscriber(subscriber, s -> s.getMatchingLines(), "\n"));
if (response.statusCode() != 200) {
    System.err.printf("ERROR: %d status received%n", response.statusCode());
}
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
lineSeparator - an optional line separator: can be null, in which case lines will be delimited in the manner of BufferedReader.readLine().
Returns:
a response body handler
Throws:
IllegalArgumentException - if the supplied lineSeparator is the empty string

discarding

public static HttpResponse.BodyHandler<Void> discarding()
Returns a response body handler that discards the response body.
Returns:
a response body handler

replacing

public static <U> HttpResponse.BodyHandler<U> replacing(U value)
Returns a response body handler that returns the given replacement value, after discarding the response body.
Type Parameters:
U - the response body type
Parameters:
value - the value of U to return as the body, may be null
Returns:
a response body handler

ofString

public static HttpResponse.BodyHandler<String> ofString(Charset charset)
Returns a BodyHandler<String> that returns a BodySubscriber<String> obtained from BodySubscribers.ofString(Charset). The body is decoded using the given character set.
Parameters:
charset - the character set to convert the body with
Returns:
a response body handler

ofFile

public static HttpResponse.BodyHandler<Path> ofFile(Path file, OpenOption... openOptions)
Returns a BodyHandler<Path> that returns a BodySubscriber<Path> obtained from BodySubscribers.ofFile(Path,OpenOption...).

When the HttpResponse object is returned, the body has been completely written to the file, and HttpResponse.body() returns a reference to its Path.

In the case of the default file system provider, security manager permission checks are performed in this factory method, when the BodyHandler is created. Otherwise, permission checks may be performed asynchronously against the caller's context at file access time. Care must be taken that the BodyHandler is not shared with untrusted code.

Parameters:
file - the file to store the body in
openOptions - any options to use when opening/creating the file
Returns:
a response body handler
Throws:
IllegalArgumentException - if an invalid set of open options are specified
SecurityException - in the case of the default file system provider, and a security manager is installed, checkWrite is invoked to check write access to the given file

ofFile

public static HttpResponse.BodyHandler<Path> ofFile(Path file)
Returns a BodyHandler<Path> that returns a BodySubscriber<Path>.

Equivalent to: ofFile(file, CREATE, WRITE)

In the case of the default file system provider, security manager permission checks are performed in this factory method, when the BodyHandler is created. Otherwise, permission checks may be performed asynchronously against the caller's context at file access time. Care must be taken that the BodyHandler is not shared with untrusted code.

Parameters:
file - the file to store the body in
Returns:
a response body handler
Throws:
SecurityException - in the case of the default file system provider, and a security manager is installed, checkWrite is invoked to check write access to the given file

ofFileDownload

public static HttpResponse.BodyHandler<Path> ofFileDownload(Path directory, OpenOption... openOptions)
Returns a BodyHandler<Path> that returns a BodySubscriber<Path> where the download directory is specified, but the filename is obtained from the Content-Disposition response header. The Content-Disposition header must specify the attachment type and must also contain a filename parameter. If the filename specifies multiple path components only the final component is used as the filename (with the given directory name).

When the HttpResponse object is returned, the body has been completely written to the file and HttpResponse.body() returns a Path object for the file. The returned Path is the combination of the supplied directory name and the file name supplied by the server. If the destination directory does not exist or cannot be written to, then the response will fail with an IOException.

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

Parameters:
directory - the directory to store the file in
openOptions - open options used when opening the file
Returns:
a response body handler
Throws:
IllegalArgumentException - if the given path does not exist, is not of the default file system, is not a directory, is not writable, or if an invalid set of open options are specified
SecurityException - in the case of the default file system provider and a security manager has been installed, and it denies read access to the directory, or it denies write access to the directory, or it denies write access to the files within the directory.

ofInputStream

public static HttpResponse.BodyHandler<InputStream> ofInputStream()
Returns a BodyHandler<InputStream> that returns a BodySubscriber<InputStream> obtained from BodySubscribers.ofInputStream.

When the HttpResponse object is returned, the response headers will have been completely read, but the body may not have been fully received yet. The HttpResponse.body() method returns an InputStream from which the body can be read as it is received.

API Note:
See HttpResponse.BodySubscribers.ofInputStream() for more information.
Returns:
a response body handler

ofLines

public static HttpResponse.BodyHandler<Stream<String>> ofLines()
Returns a BodyHandler<Stream<String>> that returns a BodySubscriber<Stream<String>> obtained from BodySubscribers.ofLines(charset). The charset used to decode the response body bytes is obtained from the HTTP response headers as specified by ofString(), and lines are delimited in the manner of BufferedReader.readLine().

When the HttpResponse object is returned, the body may not have been completely received.

Returns:
a response body handler

ofByteArrayConsumer

public static HttpResponse.BodyHandler<Void> ofByteArrayConsumer(Consumer<Optional<byte[]>> consumer)
Returns a BodyHandler<Void> that returns a BodySubscriber<Void> obtained from BodySubscribers.ofByteArrayConsumer(Consumer).

When the HttpResponse object is returned, the body has been completely written to the consumer.

API Note:
The subscriber returned by this handler 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 to accept the response body
Returns:
a response body handler

ofByteArray

public static HttpResponse.BodyHandler<byte[]> ofByteArray()
Returns a BodyHandler<byte[]> that returns a BodySubscriber<byte[]> obtained from BodySubscribers.ofByteArray().

When the HttpResponse object is returned, the body has been completely written to the byte array.

Returns:
a response body handler

ofString

public static HttpResponse.BodyHandler<String> ofString()
Returns a BodyHandler<String> that returns a BodySubscriber<String> obtained from BodySubscribers.ofString(Charset). The body is decoded using the character set specified in the Content-Type response header. If there is no such header, or the character set is not supported, then UTF_8 is used.

When the HttpResponse object is returned, the body has been completely written to the string.

Returns:
a response body handler

ofPublisher

public static HttpResponse.BodyHandler<Flow.Publisher<List<ByteBuffer>>> ofPublisher()
Returns a BodyHandler<Publisher<List<ByteBuffer>>> that creates a BodySubscriber<Publisher<List<ByteBuffer>>> obtained from BodySubscribers.ofPublisher().

When the HttpResponse object is returned, the response headers will have been completely read, but the body may not have been fully received yet. The HttpResponse.body() method returns a Publisher<List<ByteBuffer>> from which the body response bytes can be obtained as they are received. The publisher can and must be subscribed to only once.

API Note:
See HttpResponse.BodySubscribers.ofPublisher() for more information.
Returns:
a response body handler

buffering

public static <T> HttpResponse.BodyHandler<T> buffering(HttpResponse.BodyHandler<T> downstreamHandler, int bufferSize)
Returns a BodyHandler which, when invoked, returns a buffering BodySubscriber that buffers data before delivering it to the downstream subscriber. These BodySubscriber instances are created by calling BodySubscribers.buffering with a subscriber obtained from the given downstream handler and the bufferSize parameter.
Type Parameters:
T - the response body type
Parameters:
downstreamHandler - the downstream handler
bufferSize - the buffer size parameter passed to BodySubscribers.buffering
Returns:
a body handler
Throws:
IllegalArgumentException - if bufferSize <= 0

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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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