You are right that a function would be more general than a supplier.
That crossed my mind too. However, here, with greater generality comes
less convenience. Like with your example, don't you need to read a
request body and then finally close the exchange? Perhaps that can be
solved with better documentation rather than one more convenience
method. Perhaps documentation could provide (a snippet of) a skeletal
implementation of a handler.
Also, even the "static string" convenience handler is problematic: no
one sets the content type because it's unknown: the passed string can
be HTML, JSON, plain text or what have you. And no one sets the
character encoding because (AFAIK) it only comes with the content type
and not on its own.
On Mon, Apr 28, 2025 at 8:53 PM Ethan McCue <et...@mccue.dev> wrote:
>
> My first thought is that if you are computing the string maybe you'd want to
> look at the request. Or set a header for content type.
>
> I'm not going to push hard until valhalla is at least in preview (+ we've
> already talked it to death) but a Body abstraction would probably solve your
> use-case more robustly than yet another method there.
>
> exchange -> exchange.sendResponse(200, Body.of("example"));
>
> On Mon, Apr 28, 2025 at 5:28 AM Pavel Rappo <pavel.ra...@gmail.com> wrote:
>>
>> I'm using HttpServer to implement an HTTP probe [^1] that provides
>> application state at the time of probing. I find that convenience
>> handlers provided by HttpHandlers are insufficient for my use case. I
>> also find that implementing a custom HttpHandler is tricky without the
>> help of documentation.
>>
>> Perhaps my use case is typical enough so that HttpHandlers could
>> provide a new convenience handler. That handler would send a
>> dynamically supplied string, rather than a static string. If you also
>> find it useful, I'd appreciate it if we could discuss it. Before I
>> create a JBS issue, please have a look at this crude patch to see if
>> it makes sense to you in principle. Thanks.
>>
>> [^1]:
>> https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/
>>
>> diff --git
>> a/src/jdk.httpserver/share/classes/com/sun/net/httpserver/HttpHandlers.java
>> b/src/jdk.httpserver/share/classes/com/sun/net/httpserver/HttpHandlers.java
>> index 03642033914..987de0ede5d 100644
>> ---
>> a/src/jdk.httpserver/share/classes/com/sun/net/httpserver/HttpHandlers.java
>> +++
>> b/src/jdk.httpserver/share/classes/com/sun/net/httpserver/HttpHandlers.java
>> @@ -25,9 +25,11 @@
>>
>> package com.sun.net.httpserver;
>>
>> +import java.io.OutputStream;
>> import java.nio.charset.StandardCharsets;
>> import java.util.Objects;
>> import java.util.function.Predicate;
>> +import java.util.function.Supplier;
>>
>> /**
>> * Implementations of {@link com.sun.net.httpserver.HttpHandler HttpHandler}
>> @@ -140,28 +142,60 @@ public static HttpHandler
>> handleOrElse(Predicate<Request> handlerTest,
>> * @throws NullPointerException if headers or body are null
>> */
>> public static HttpHandler of(int statusCode, Headers headers,
>> String body) {
>> + Objects.requireNonNull(body);
>> + return of(statusCode, headers, () -> body);
>> + }
>> +
>> + /**
>> + * Returns an {@code HttpHandler} that sends a response
>> comprising the given
>> + * {@code statusCode}, {@code headers}, and {@code body}.
>> + *
>> + * <p> This method creates a handler that reads and discards the request
>> + * body before it sets the response state and sends the response.
>> + *
>> + * <p> {@code headers} are the effective headers of the response. The
>> + * response <i>body bytes</i> are a {@code UTF-8} encoded byte sequence
>> of
>> + * a string, which is supplied by {@code bodySupplier}
>> immediately after the request body is read. The response headers
>> + * {@linkplain HttpExchange#sendResponseHeaders(int, long) are sent}
>> with
>> + * the given {@code statusCode} and the body bytes' length (or {@code
>> -1}
>> + * if the body is empty). The body bytes are then sent as response body,
>> + * unless the body is empty, in which case no response body is sent.
>> + *
>> + * @param statusCode a response status code
>> + * @param headers a headers
>> + * @param bodySupplier a supplier for the response body string
>> + * @return a handler
>> + * @throws IllegalArgumentException if statusCode is not a positive
>> 3-digit
>> + * integer, as per rfc2616, section
>> 6.1.1
>> + * @throws NullPointerException if headers or body are null
>> + */
>> + public static HttpHandler of(int statusCode, Headers headers,
>> Supplier<String> bodySupplier) {
>> if (statusCode < 100 || statusCode > 999)
>> throw new IllegalArgumentException("statusCode must be 3-digit:
>> "
>> + statusCode);
>> Objects.requireNonNull(headers);
>> - Objects.requireNonNull(body);
>> + Objects.requireNonNull(bodySupplier);
>>
>> final var headersCopy = Headers.of(headers);
>> - final var bytes = body.getBytes(StandardCharsets.UTF_8);
>>
>> return exchange -> {
>> try (exchange) {
>> - exchange.getRequestBody().readAllBytes();
>> +
>> exchange.getRequestBody().transferTo(OutputStream.nullOutputStream());
>> // discard
>> exchange.getResponseHeaders().putAll(headersCopy);
>> - if (exchange.getRequestMethod().equals("HEAD")) {
>> -
>> exchange.getResponseHeaders().set("Content-Length",
>> Integer.toString(bytes.length));
>> - exchange.sendResponseHeaders(statusCode, -1);
>> - }
>> - else if (bytes.length == 0) {
>> - exchange.sendResponseHeaders(statusCode, -1);
>> + var body = bodySupplier.get();
>> + if (body == null) {
>> + exchange.sendResponseHeaders(500, -1); //
>> Internal Server Error
>> } else {
>> - exchange.sendResponseHeaders(statusCode, bytes.length);
>> - exchange.getResponseBody().write(bytes);
>> + final var bytes = body.getBytes(StandardCharsets.UTF_8);
>> + if (exchange.getRequestMethod().equals("HEAD")) {
>> +
>> exchange.getResponseHeaders().set("Content-Length",
>> Integer.toString(bytes.length));
>> + exchange.sendResponseHeaders(statusCode, -1);
>> + } else if (bytes.length == 0) {
>> + exchange.sendResponseHeaders(statusCode, -1);
>> + } else {
>> + exchange.sendResponseHeaders(statusCode,
>> bytes.length);
>> + exchange.getResponseBody().write(bytes);
>> + }
>> }
>> }
>> };
>> diff --git
>> a/test/jdk/com/sun/net/httpserver/simpleserver/HttpHandlersTest.java
>> b/test/jdk/com/sun/net/httpserver/simpleserver/HttpHandlersTest.java
>> index 85d271e44fa..d64fa03740f 100644
>> --- a/test/jdk/com/sun/net/httpserver/simpleserver/HttpHandlersTest.java
>> +++ b/test/jdk/com/sun/net/httpserver/simpleserver/HttpHandlersTest.java
>> @@ -81,7 +81,7 @@ public void testNull() {
>> final var headers = new Headers();
>> final var body = "";
>> assertThrows(NPE, () -> HttpHandlers.of(200, null, body));
>> - assertThrows(NPE, () -> HttpHandlers.of(200, headers, null));
>> + assertThrows(NPE, () -> HttpHandlers.of(200, headers, (String)
>> null));
>> }
>>
>> @Test
