Class HttpHandlers

java.lang.Object

com.sun.net.httpserver.HttpHandlers

public final class HttpHandlers
extends Object

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.

Since:

18

Method Summary

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

Methods declared in class Object

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

Modifier and Type	Method	Description
protected Object	clone()	Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
boolean	equals(Object o)	Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. May cause performance issues, deadlocks and hangs.
final Class<? extends Object>	getClass()	Answers the unique instance of java.lang.Class which represents the class of the receiver.
int	hashCode()	Answers an integer hash code for the receiver.
final void	notify()	Causes one thread which is waiting on the receiver to be made ready to run.
final void	notifyAll()	Causes all threads which are waiting on the receiver to be made ready to run.
String	toString()	Answers a string containing a concise, human-readable description of the receiver.
final void	wait()	Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by notify or notifyAll).
final void	wait(long time)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.
final void	wait(long time, int frac)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.

Method Details

handleOrElse

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 - a request predicate

handler - a conditional handler

fallbackHandler - a fallback handler

Returns:

a handler

Throws:

NullPointerException - if any argument is null

of

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 - a response status code

headers - a headers

body - a response body string

Returns:

a handler

Throws:

IllegalArgumentException - if statusCode is not a positive 3-digit integer, as per rfc2616, section 6.1.1

NullPointerException - if headers or body are null