Introduce DelegatingMcp(Async)HttpRequestCustomizer

Author: Kehrlann

mcp/src/main/java/io/modelcontextprotocol/client/transport/customizer/DelegatingMcpAsyncHttpRequestCustomizer.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2024-2025 the original author or authors.
+ */
+package io.modelcontextprotocol.client.transport.customizer;
+
+import io.modelcontextprotocol.util.Assert;
+import java.net.URI;
+import java.net.http.HttpRequest;
+import java.util.List;
+import org.reactivestreams.Publisher;
+import reactor.core.publisher.Mono;
+
+/**
+ * Composable {@link McpAsyncHttpRequestCustomizer} that applies multiple customizers, in
+ * order.
+ *
+ * @author Daniel Garnier-Moiroux
+ */
+public class DelegatingMcpAsyncHttpRequestCustomizer implements McpAsyncHttpRequestCustomizer {
+
+	private final List<McpAsyncHttpRequestCustomizer> customizers;
+
+	public DelegatingMcpAsyncHttpRequestCustomizer(List<McpAsyncHttpRequestCustomizer> customizers) {
+		Assert.notNull(customizers, "Customizers must not be null");
+		this.customizers = customizers;
+	}
+
+	@Override
+	public Publisher<HttpRequest.Builder> customize(HttpRequest.Builder builder, String method, URI endpoint,
+			String body) {
+		var result = Mono.just(builder);
+		for (var customizer : this.customizers) {
+			result = result.flatMap(b -> Mono.from(customizer.customize(b, method, endpoint, body)));
+		}
+		return result;
+	}
+
+}

mcp/src/main/java/io/modelcontextprotocol/client/transport/customizer/DelegatingMcpSyncHttpRequestCustomizer.java

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+/*
+ * Copyright 2024-2025 the original author or authors.
+ */
+
+package io.modelcontextprotocol.client.transport.customizer;
+
+import io.modelcontextprotocol.util.Assert;
+import java.net.URI;
+import java.net.http.HttpRequest;
+import java.util.List;
+
+/**
+ * Composable {@link McpSyncHttpRequestCustomizer} that applies multiple customizers, in
+ * order.
+ *
+ * @author Daniel Garnier-Moiroux
+ */
+public class DelegatingMcpSyncHttpRequestCustomizer implements McpSyncHttpRequestCustomizer {
+
+	private final List<McpSyncHttpRequestCustomizer> delegates;
+
+	public DelegatingMcpSyncHttpRequestCustomizer(List<McpSyncHttpRequestCustomizer> customizers) {
+		Assert.notNull(customizers, "Customizers must not be null");
+		this.delegates = customizers;
+	}
+
+	@Override
+	public void customize(HttpRequest.Builder builder, String method, URI endpoint, String body) {
+		this.delegates.forEach(delegate -> delegate.customize(builder, method, endpoint, body));
+	}
+
+}

mcp/src/test/java/io/modelcontextprotocol/client/transport/customizer/DelegatingMcpAsyncHttpRequestCustomizerTest.java

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+/*
+ * Copyright 2024-2025 the original author or authors.
+ */
+
+package io.modelcontextprotocol.client.transport.customizer;
+
+import java.net.URI;
+import java.net.http.HttpRequest;
+import java.util.List;
+import org.junit.jupiter.api.Test;
+import reactor.core.publisher.Mono;
+import reactor.test.StepVerifier;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+/**
+ * Tests for {@link DelegatingMcpAsyncHttpRequestCustomizer}.
+ *
+ * @author Daniel Garnier-Moiroux
+ */
+class DelegatingMcpAsyncHttpRequestCustomizerTest {
+
+	private static final URI TEST_URI = URI.create("https://example.com");
+
+	private final HttpRequest.Builder TEST_BUILDER = HttpRequest.newBuilder(TEST_URI);
+
+	@Test
+	void delegates() {
+		var mockCustomizer = mock(McpAsyncHttpRequestCustomizer.class);
+		when(mockCustomizer.customize(any(), any(), any(), any()))
+			.thenAnswer(invocation -> Mono.just(invocation.getArguments()[0]));
+		var customizer = new DelegatingMcpAsyncHttpRequestCustomizer(List.of(mockCustomizer));
+
+		StepVerifier.create(customizer.customize(TEST_BUILDER, "GET", TEST_URI, "{\"everybody\": \"needs somebody\"}"))
+			.expectNext(TEST_BUILDER)
+			.verifyComplete();
+
+		verify(mockCustomizer).customize(TEST_BUILDER, "GET", TEST_URI, "{\"everybody\": \"needs somebody\"}");
+	}
+
+	@Test
+	void delegatesInOrder() {
+		var customizer = new DelegatingMcpAsyncHttpRequestCustomizer(
+				List.of((builder, method, uri, body) -> Mono.just(builder.copy().header("x-test", "one")),
+						(builder, method, uri, body) -> Mono.just(builder.copy().header("x-test", "two"))));
+
+		var headers = Mono
+			.from(customizer.customize(TEST_BUILDER, "GET", TEST_URI, "{\"everybody\": \"needs somebody\"}"))
+			.map(HttpRequest.Builder::build)
+			.map(HttpRequest::headers)
+			.flatMapIterable(h -> h.allValues("x-test"));
+
+		StepVerifier.create(headers).expectNext("one").expectNext("two").verifyComplete();
+	}
+
+	@Test
+	void constructorRequiresNonNull() {
+		assertThatThrownBy(() -> new DelegatingMcpAsyncHttpRequestCustomizer(null))
+			.isInstanceOf(IllegalArgumentException.class)
+			.hasMessage("Customizers must not be null");
+	}
+
+}

mcp/src/test/java/io/modelcontextprotocol/client/transport/customizer/DelegatingMcpSyncHttpRequestCustomizerTest.java

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+/*
+ * Copyright 2024-2025 the original author or authors.
+ */
+
+package io.modelcontextprotocol.client.transport.customizer;
+
+import java.net.URI;
+import java.net.http.HttpRequest;
+import java.util.List;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.mockito.Mockito.verify;
+
+/**
+ * Tests for {@link DelegatingMcpSyncHttpRequestCustomizer}.
+ *
+ * @author Daniel Garnier-Moiroux
+ */
+class DelegatingMcpSyncHttpRequestCustomizerTest {
+
+	private static final URI TEST_URI = URI.create("https://example.com");
+
+	private final HttpRequest.Builder TEST_BUILDER = HttpRequest.newBuilder(TEST_URI);
+
+	@Test
+	void delegates() {
+		var mockCustomizer = Mockito.mock(McpSyncHttpRequestCustomizer.class);
+		var customizer = new DelegatingMcpSyncHttpRequestCustomizer(List.of(mockCustomizer));
+
+		customizer.customize(TEST_BUILDER, "GET", TEST_URI, "{\"everybody\": \"needs somebody\"}");
+
+		verify(mockCustomizer).customize(TEST_BUILDER, "GET", TEST_URI, "{\"everybody\": \"needs somebody\"}");
+	}
+
+	@Test
+	void delegatesInOrder() {
+		var testHeaderName = "x-test";
+		var customizer = new DelegatingMcpSyncHttpRequestCustomizer(
+				List.of((builder, method, uri, body) -> builder.header(testHeaderName, "one"),
+						(builder, method, uri, body) -> builder.header(testHeaderName, "two")));
+
+		customizer.customize(TEST_BUILDER, "GET", TEST_URI, "");
+		var request = TEST_BUILDER.build();
+
+		assertThat(request.headers().allValues(testHeaderName)).containsExactly("one", "two");
+	}
+
+	@Test
+	void constructorRequiresNonNull() {
+		assertThatThrownBy(() -> new DelegatingMcpAsyncHttpRequestCustomizer(null))
+			.isInstanceOf(IllegalArgumentException.class)
+			.hasMessage("Customizers must not be null");
+	}
+
+}