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davidmartinezbaruadavidmartinezbarua
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Merge pull request #18937 from brokenhardisk/master
BAEL-9308: Java SDK for MCP
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‎java-mcp/pom.xml‎

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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<artifactId>java-mcp</artifactId>
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<name>java-mcp</name>
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<parent>
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<groupId>com.baeldung</groupId>
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<artifactId>parent-modules</artifactId>
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<version>1.0.0-SNAPSHOT</version>
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</parent>
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<dependencies>
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<dependency>
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<groupId>io.modelcontextprotocol.sdk</groupId>
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<artifactId>mcp</artifactId>
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<version>${mcp.version}</version>
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</dependency>
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</dependencies>
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<build>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-shade-plugin</artifactId>
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<version>3.5.0</version>
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<executions>
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<execution>
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<phase>package</phase>
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<goals>
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<goal>shade</goal>
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</goals>
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<configuration>
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<transformers>
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<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
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<mainClass>mcp.McpServerApp</mainClass>
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</transformer>
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</transformers>
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</configuration>
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</execution>
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</executions>
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</plugin>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-compiler-plugin</artifactId>
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<configuration>
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<source>21</source>
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<target>21</target>
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</configuration>
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</plugin>
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</plugins>
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</build>
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<properties>
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<mcp.version>0.15.0</mcp.version>
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</properties>
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</project>

‎java-mcp/src/main/java/mcp/LoggingTool.java‎

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package mcp;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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import io.modelcontextprotocol.server.McpServerFeatures;
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import io.modelcontextprotocol.spec.McpSchema;
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public class LoggingTool {
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public static McpServerFeatures.SyncToolSpecification logPromptTool() {
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McpSchema.JsonSchema inputSchema = new McpSchema.JsonSchema("object", Map.of("prompt", String.class), List.of("prompt"), false, null, null);
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return new McpServerFeatures.SyncToolSpecification(
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new McpSchema.Tool("logPrompt", "Log Prompt", "Logs a provided prompt", inputSchema, null, null, null), (exchange, args) -> {
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String prompt = (String) args.get("prompt");
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return McpSchema.CallToolResult.builder()
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.content(List.of(new McpSchema.TextContent("Input Prompt: " + prompt)))
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.isError(false)
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.build();
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});
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}
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}

‎java-mcp/src/main/java/mcp/McpClientApp.java‎

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package mcp;
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import com.fasterxml.jackson.databind.ObjectMapper;
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import io.modelcontextprotocol.client.McpSyncClient;
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import io.modelcontextprotocol.client.transport.ServerParameters;
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import io.modelcontextprotocol.client.transport.StdioClientTransport;
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import io.modelcontextprotocol.json.jackson.JacksonMcpJsonMapper;
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import io.modelcontextprotocol.spec.McpClientTransport;
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public class McpClientApp {
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public static McpSyncClient getClient() {
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ServerParameters params = ServerParameters.builder("npx")
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.args("-y", "@modelcontextprotocol/server-everything")
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.build();
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JacksonMcpJsonMapper jsonMapper = new JacksonMcpJsonMapper(new ObjectMapper());
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McpClientTransport transport = new StdioClientTransport(params, jsonMapper);
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return io.modelcontextprotocol.client.McpClient.sync(transport)
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.build();
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}
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public static void main(String[] args) {
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McpSyncClient client = getClient();
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client.initialize();
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}
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}

‎java-mcp/src/main/java/mcp/McpClientApp2.java‎

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package mcp;
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import java.io.IOException;
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import java.util.Map;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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import com.fasterxml.jackson.databind.ObjectMapper;
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import io.modelcontextprotocol.client.McpClient;
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import io.modelcontextprotocol.client.McpSyncClient;
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import io.modelcontextprotocol.client.transport.ServerParameters;
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import io.modelcontextprotocol.client.transport.StdioClientTransport;
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import io.modelcontextprotocol.json.jackson.JacksonMcpJsonMapper;
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import io.modelcontextprotocol.spec.McpClientTransport;
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import io.modelcontextprotocol.spec.McpSchema.CallToolRequest;
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import io.modelcontextprotocol.spec.McpSchema.CallToolResult;
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import io.modelcontextprotocol.spec.McpSchema.ListToolsResult;
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public class McpClientApp2 {
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private static final Logger log = LoggerFactory.getLogger(McpClientApp2.class);
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public static void main(String[] args) {
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String jarPath = new java.io.File("java-mcp/target/java-mcp-1.0.0-SNAPSHOT.jar").getAbsolutePath();
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ServerParameters params = ServerParameters.builder("java")
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.args("-jar", jarPath)
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.build();
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JacksonMcpJsonMapper jsonMapper = new JacksonMcpJsonMapper(new ObjectMapper());
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McpClientTransport transport = new StdioClientTransport(params, jsonMapper);
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McpSyncClient client = McpClient.sync(transport)
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.build();
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client.initialize();
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ListToolsResult tools = client.listTools();
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McpClientApp2.log.info("Tools exposed by the server:");
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tools.tools()
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.forEach(tool -> System.out.println(" - " + tool.name()));
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McpClientApp2.log.info("\nCalling 'logPrompt' tool...");
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CallToolResult result = client.callTool(new CallToolRequest("logPrompt", Map.of("prompt", "Hello from MCP client!")));
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McpClientApp2.log.info("Result: " + result.content());
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client.closeGracefully();
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}
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}

‎java-mcp/src/main/java/mcp/McpServerApp.java‎

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package mcp;
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import com.fasterxml.jackson.databind.ObjectMapper;
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import io.modelcontextprotocol.json.jackson.JacksonMcpJsonMapper;
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import io.modelcontextprotocol.server.McpServer;
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import io.modelcontextprotocol.server.McpSyncServer;
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import io.modelcontextprotocol.server.transport.StdioServerTransportProvider;
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import io.modelcontextprotocol.spec.McpSchema;
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public class McpServerApp {
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public static McpSyncServer createServer() {
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JacksonMcpJsonMapper jsonMapper = new JacksonMcpJsonMapper(new ObjectMapper());
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StdioServerTransportProvider transportProvider = new StdioServerTransportProvider(jsonMapper);
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return McpServer.sync(transportProvider)
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.serverInfo("baeldung-demo-server", "0.0.1")
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.capabilities(McpSchema.ServerCapabilities.builder()
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.tools(true)
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.logging()
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.build())
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.tools(LoggingTool.logPromptTool())
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.build();
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}
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public static void main(String[] args) {
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createServer();
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}
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}

‎java-mcp/src/main/resources/logback.xml‎

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<configuration>
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<appender name="STDERR" class="ch.qos.logback.core.ConsoleAppender">
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<target>System.err</target>
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<encoder>
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<pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
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</encoder>
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</appender>
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<root level="info">
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<appender-ref ref="STDERR"/>
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</root>
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</configuration>

‎java-mcp/src/test/java/mcp/McpClientAppServerUnitTest.java‎

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package mcp;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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import static org.junit.jupiter.api.Assertions.assertFalse;
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import static org.junit.jupiter.api.Assertions.assertNotNull;
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import static org.junit.jupiter.api.Assertions.assertNull;
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import java.util.Map;
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import org.junit.jupiter.api.BeforeAll;
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import org.junit.jupiter.api.Test;
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import io.modelcontextprotocol.client.McpSyncClient;
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import io.modelcontextprotocol.server.McpServerFeatures;
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import io.modelcontextprotocol.spec.McpSchema;
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class McpClientAppServerUnitTest {
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private static McpSyncClient client;
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@BeforeAll
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static void init() {
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client = McpClientApp.getClient();
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client.initialize();
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}
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@Test
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void whenLogPromptToolCalled_thenReturnsResult() {
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McpSchema.CallToolRequest request = new McpSchema.CallToolRequest("", Map.of("prompt", "Unit test message"));
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McpServerFeatures.SyncToolSpecification toolSpec = LoggingTool.logPromptTool();
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McpSchema.CallToolResult result = toolSpec.callHandler()
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.apply(null, request);
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assertNotNull(result);
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assertFalse(result.isError());
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assertEquals("Input Prompt: Unit test message", ((McpSchema.TextContent) (result.content()
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.getFirst())).text());
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}
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@Test
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void whenCalledViaClient_thenReturnsLoggedResult() {
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McpSchema.CallToolRequest request = new McpSchema.CallToolRequest("echo", Map.of("message", "Client-server test message"));
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McpSchema.CallToolResult result = client.callTool(request);
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assertNotNull(result);
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assertNull(result.isError());
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assertEquals("Echo: Client-server test message", ((McpSchema.TextContent) (result.content()
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.getFirst())).text());
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}
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}
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‎pom.xml‎

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<module>web-modules</module>
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<module>webrtc</module>
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<module>xml-modules</module>
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<module>java-mcp</module>
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</modules>
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<properties>

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