Package io.helidon.webserver

Class RequestPredicate

java.lang.Object

io.helidon.webserver.RequestPredicate

public final class RequestPredicate
extends Object

Fluent API that allows to create chains of request conditions for composing logical expressions to match requests.

A new expression can be created using the create() method. This method will initialize an expression with an empty condition that will match any request.

Conditions are added to the expression by chaining method invocations and form a logical AND expression. Each method invocation will return a different instance representing the last condition in the expression. Each instance can represent only one condition, invoking a method representing a condition more than once per instance will throw an IllegalStateException.

The expression can be evaluated against a request using the test(ServerRequest) method, or a RequestPredicate.ConditionalHandler can be used to evaluate the expression and delegate to other handlers based on the result of the evaluation.

The thenApply(Handler) method can be invoked on an expression to create a RequestPredicate.ConditionalHandler.

The handler to be used for matching requests is passed as parameter to thenApply(Handler) and the handler to be used for requests that do not match can be specified using RequestPredicate.ConditionalHandler.otherwise(Handler).

Examples

Invoke a Handler only when the request contains a header name foo and accepts text/plain, otherwise return a response with 404 code.

 RequestPredicate.create()
                 .containsHeader("foo")
                 .accepts(MediaType.TEXT_PLAIN)
                 .thenApply((req, resp) -> {
                     // handler logic
                 });
 

Invoke a Handler only when the request contains a header named foo otherwise invoke another handler that throws an exception.

 RequestPredicate.create()
                 .containsHeader("foo")
                 .thenApply((req, resp) -> {
                     // handler logic
                 })
                 .otherwise(req, resp) -> {
                     throw new RuntimeException("Missing 'foo' header!");
                 });
 

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	RequestPredicate.ConditionalHandler	A Handler that conditionally delegates to other Handler instances based on a RequestPredicate.

Method Summary

Modifier and Type	Method	Description
RequestPredicate	accepts(MediaType... contentType)	Only accept request that accepts any of the given content types.
RequestPredicate	accepts(String... contentType)	Accept requests only when it accepts any of the given content types.
RequestPredicate	and(Predicate<ServerRequest> predicate)	Returns a composed predicate that represents a logical AND expression between this predicate and another predicate.
RequestPredicate	containsCookie(String name)	Accept request only when the specified cookie exists.
RequestPredicate	containsCookie(String name, String value)	Accept requests only when the specified cookie contains a given value.
RequestPredicate	containsCookie(String name, Predicate<String> predicate)	Accept requests only when the specified cookie is valid.
RequestPredicate	containsHeader(String name)	Accept requests only when the specified header name exists.
RequestPredicate	containsHeader(String name, String value)	Accept requests only when the specified header contains a given value.
RequestPredicate	containsHeader(String name, Predicate<String> predicate)	Accept requests only when the specified header is valid.
RequestPredicate	containsQueryParameter(String name)	Accept requests only when the specified query parameter exists.
RequestPredicate	containsQueryParameter(String name, String value)	Accept requests only when the specified query parameter contains a given value.
RequestPredicate	containsQueryParameter(String name, Predicate<String> predicate)	Accept requests only when the specified query parameter is valid.
static RequestPredicate	create()	Creates new empty RequestPredicate instance.
RequestPredicate	hasContentType(MediaType... contentType)	Only accept requests with any of the given content types.
RequestPredicate	hasContentType(String... contentType)	Only accept requests with any of the given content types.
RequestPredicate	isOfMethod(Http.Method... methods)	Accepts only requests with one of specified HTTP methods.
RequestPredicate	isOfMethod(String... methods)	Accepts only requests with one of specified HTTP methods.
RequestPredicate	negate()	Return a predicate that represents the logical negation of this predicate.
RequestPredicate	or(Predicate<ServerRequest> predicate)	Returns a composed predicate that represents a logical OR expression between this predicate and another predicate.
boolean	test(ServerRequest request)	Evaluate this predicate.
RequestPredicate.ConditionalHandler	thenApply(Handler handler)	Set the Handler to use when this predicate matches the request.

Methods inherited from class java.lang.Object

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

Method Detail

thenApply

public RequestPredicate.ConditionalHandler thenApply(Handler handler)

Set the Handler to use when this predicate matches the request.

Parameters:

handler - handler to use this predicate instance matches

Returns:

instance of RequestPredicate.ConditionalHandler that can be used to specify another Handler to use when this predicates does not match the request

See Also:

RequestPredicate.ConditionalHandler.otherwise(Handler)

test

public boolean test(ServerRequest request)

Evaluate this predicate.

Parameters:

request - the server request

Returns:

the computed value

and

public RequestPredicate and(Predicate<ServerRequest> predicate)

Returns a composed predicate that represents a logical AND expression between this predicate and another predicate.

Parameters:

predicate - predicate to compose with

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

or

public RequestPredicate or(Predicate<ServerRequest> predicate)

Returns a composed predicate that represents a logical OR expression between this predicate and another predicate.

Parameters:

predicate - predicate that compute the new value

Returns:

composed predicate representing the logical expression between this predicate OR the provided predicate

negate

public RequestPredicate negate()

Return a predicate that represents the logical negation of this predicate.

Returns:

new predicate that represents the logical negation of this predicate.

isOfMethod

public RequestPredicate isOfMethod(String... methods)

Accepts only requests with one of specified HTTP methods.

Parameters:

methods - Acceptable method names

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

Throws:

NullPointerException - if the specified methods array is null

isOfMethod

public RequestPredicate isOfMethod(Http.Method... methods)

Accepts only requests with one of specified HTTP methods.

Parameters:

methods - Acceptable method names

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

Throws:

NullPointerException - if the methods type array is null

containsHeader

public RequestPredicate containsHeader(String name)

Accept requests only when the specified header name exists.

Parameters:

name - header name

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

Throws:

NullPointerException - if the specified name is null

containsHeader

public RequestPredicate containsHeader(String name,
                                       String value)

Accept requests only when the specified header contains a given value. If the request contains more then one header, it will be accepted if any of the values is equal to the provided value.

Parameters:

name - header name

value - the expected header value

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

Throws:

NullPointerException - if the specified name or value is null

containsHeader

public RequestPredicate containsHeader(String name,
                                       Predicate<String> predicate)

Accept requests only when the specified header is valid. A header is valid when the supplied predicate matches the header value. If the request contains more than one header, it will be accepted if the predicate matches any of the values.

Parameters:

name - header name

predicate - predicate to match the header value

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

Throws:

NullPointerException - if the specified name or predicate is null

containsQueryParameter

public RequestPredicate containsQueryParameter(String name)

Accept requests only when the specified query parameter exists.

Parameters:

name - query parameter name

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

Throws:

NullPointerException - if the specified name is null

containsQueryParameter

public RequestPredicate containsQueryParameter(String name,
                                               String value)

Accept requests only when the specified query parameter contains a given value.

Parameters:

name - query parameter name

value - expected query parameter value

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

Throws:

NullPointerException - if the specified name or value is null

containsQueryParameter

public RequestPredicate containsQueryParameter(String name,
                                               Predicate<String> predicate)

Accept requests only when the specified query parameter is valid.

Parameters:

name - query parameter name

predicate - to match the query parameter value

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

Throws:

NullPointerException - if the specified name or predicate is null

containsCookie

public RequestPredicate containsCookie(String name)

Accept request only when the specified cookie exists.

Parameters:

name - cookie name

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

Throws:

NullPointerException - if the specified name is null

containsCookie

public RequestPredicate containsCookie(String name,
                                       String value)

Accept requests only when the specified cookie contains a given value.

Parameters:

name - cookie name

value - expected cookie value

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

Throws:

NullPointerException - if the specified name or value is null

containsCookie

public RequestPredicate containsCookie(String name,
                                       Predicate<String> predicate)

Accept requests only when the specified cookie is valid.

Parameters:

name - cookie name

predicate - predicate to match the cookie value

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

Throws:

NullPointerException - if the specified name or predicate is null

accepts

public RequestPredicate accepts(String... contentType)

Accept requests only when it accepts any of the given content types.

Parameters:

contentType - the content types to test

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

Throws:

NullPointerException - if the specified content type array is null

accepts

public RequestPredicate accepts(MediaType... contentType)

Only accept request that accepts any of the given content types.

Parameters:

contentType - the content types to test

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

Throws:

NullPointerException - if the specified content type array is null

hasContentType

public RequestPredicate hasContentType(String... contentType)

Only accept requests with any of the given content types.

Parameters:

contentType - Content type

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

Throws:

NullPointerException - if the specified content type array is null

hasContentType

public RequestPredicate hasContentType(MediaType... contentType)

Only accept requests with any of the given content types.

Parameters:

contentType - Content type

Returns:

composed predicate representing the logical expression between this predicate AND the provided predicate

Throws:

NullPointerException - if the specified content type array is null

create

public static RequestPredicate create()

Creates new empty RequestPredicate instance.

Returns:

new empty predicate (accepts all requests).