OpenJDK 27 · com.sun.net.httpserver.HttpHandlers · APIdia, the JavaDoc alternative

Implementations of HttpHandler that implement various useful handlers, such as a static response handler, or a conditional handler that complements one handler with another.

The factory method of(int, Headers, String) provides a means to create handlers with pre-set static response state. For example, a jsonHandler that always returns 200 with the same json:

HttpHandlers.of(200,
                   Headers.of("Content-Type", "application/json"),
                   Files.readString(Path.of("some.json")));

or a notAllowedHandler that always replies with 405 - Method Not Allowed, and indicates the set of methods that are allowed:

HttpHandlers.of(405, Headers.of("Allow", "GET"), "");

The functionality of a handler can be extended or enhanced through the use of handleOrElse, which allows to complement a given handler. For example, complementing a jsonHandler with notAllowedHandler:

Predicate<Request> IS_GET = r -> r.getRequestMethod().equals("GET");
   var handler = HttpHandlers.handleOrElse(IS_GET, jsonHandler, notAllowedHandler);

The above handleOrElse handler offers an if-else like construct; if the request method is "GET" then handling of the exchange is delegated to the jsonHandler, otherwise handling of the exchange is delegated to the notAllowedHandler.

Access	Constructor and Description
private	HttpHandlers()

Method Summary

Modifier and Type	Method and Description
public static HttpHandler	Returns: a handler handleOrElse(Predicate<Request> a request predicate handlerTest, HttpHandler a conditional handler handler, HttpHandler a fallback handler fallbackHandler) Complements a conditional `HttpHandler` with another handler.
public static HttpHandler	Returns: a handler of(int a response status code statusCode, Headers a headers headers, String a response body string body) Returns an `HttpHandler` that sends a response comprising the given `statusCode`, `headers`, and `body`.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Constructor Detail

HttpHandlers	back to summary
private HttpHandlers()

Method Detail

handleOrElse back to summary

handleOrElse	back to summary
public static HttpHandler handleOrElse(Predicate<Request> handlerTest, HttpHandler handler, HttpHandler fallbackHandler) Complements a conditional `HttpHandler` with another handler. This method creates a handleOrElse handler; an if-else like construct. Exchanges who's request matches the `handlerTest` predicate are handled by the `handler`. All remaining exchanges are handled by the `fallbackHandler`. Example of a nested handleOrElse handler: `Predicate<Request> IS_GET = r -> r.getRequestMethod().equals("GET"); Predicate<Request> WANTS_DIGEST = r -> r.getRequestHeaders().containsKey("Want-Digest"); var h1 = new SomeHandler(); var h2 = HttpHandlers.handleOrElse(IS_GET, new SomeGetHandler(), h1); var h3 = HttpHandlers.handleOrElse(WANTS_DIGEST.and(IS_GET), new SomeDigestHandler(), h2);` The `h3` handleOrElse handler delegates handling of the exchange to `SomeDigestHandler` if the "Want-Digest" request header is present and the request method is `GET`, otherwise it delegates handling of the exchange to the `h2` handler. The `h2` handleOrElse handler, in turn, delegates handling of the exchange to `SomeGetHandler` if the request method is `GET`, otherwise it delegates handling of the exchange to the `h1` handler. The `h1` handler handles all exchanges that are not previously delegated to either `SomeGetHandler` or `SomeDigestHandler`. Parameters handlerTest:Predicate<Request> a request predicate handler:HttpHandler a conditional handler fallbackHandler:HttpHandler a fallback handler Returns:HttpHandler a handler Exceptions NullPointerException: if any argument is null

public static HttpHandler handleOrElse(Predicate<Request> handlerTest, HttpHandler handler, HttpHandler fallbackHandler)

Complements a conditional HttpHandler with another handler.

This method creates a handleOrElse handler; an if-else like construct. Exchanges who's request matches the handlerTest predicate are handled by the handler. All remaining exchanges are handled by the fallbackHandler.

Example of a nested handleOrElse handler:

Predicate<Request> IS_GET = r -> r.getRequestMethod().equals("GET");
   Predicate<Request> WANTS_DIGEST =  r -> r.getRequestHeaders().containsKey("Want-Digest");

   var h1 = new SomeHandler();
   var h2 = HttpHandlers.handleOrElse(IS_GET, new SomeGetHandler(), h1);
   var h3 = HttpHandlers.handleOrElse(WANTS_DIGEST.and(IS_GET), new SomeDigestHandler(), h2);

The h3 handleOrElse handler delegates handling of the exchange to SomeDigestHandler if the "Want-Digest" request header is present and the request method is GET, otherwise it delegates handling of the exchange to the h2 handler. The h2 handleOrElse handler, in turn, delegates handling of the exchange to SomeGetHandler if the request method is GET, otherwise it delegates handling of the exchange to the h1 handler. The h1 handler handles all exchanges that are not previously delegated to either SomeGetHandler or SomeDigestHandler.

Parameters

handlerTest:Predicate<Request>: a request predicate
handler:HttpHandler: a conditional handler
fallbackHandler:HttpHandler: a fallback handler

Returns:HttpHandler

a handler

Exceptions

NullPointerException:: if any argument is null

of back to summary

of	back to summary
public static HttpHandler of(int statusCode, Headers headers, String body) Returns an `HttpHandler` that sends a response comprising the given `statusCode`, `headers`, and `body`. This method creates a handler that reads and discards the request body before it sets the response state and sends the response. `headers` are the effective headers of the response. The response body bytes are a `UTF-8` encoded byte sequence of `body`. The response headers are sent with the given `statusCode` and the body bytes' length (or `-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. Parameters statusCode:int a response status code headers:Headers a headers body:String a response body string Returns:HttpHandler a handler Exceptions IllegalArgumentException: if statusCode is not a positive 3-digit integer, as per rfc2616, section 6.1.1 NullPointerException: if headers or body are null

public static HttpHandler of(int statusCode, Headers headers, String body)

Returns an HttpHandler that sends a response comprising the given statusCode, headers, and body.

This method creates a handler that reads and discards the request body before it sets the response state and sends the response.

headers are the effective headers of the response. The response body bytes are a UTF-8 encoded byte sequence of body. The response headers are sent with the given statusCode and the body bytes' length (or -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.