使用Maven+Tomcat的Ktor项目Kotlinx.serialization无响应体问题

问题描述 #

通过start.ktor.io创建Ktor 3.0.2项目，配置详情：

• 构建系统：Maven
• 引擎：Tomcat
• 配置方式：代码式配置
• 集成插件：Content Negotiation、Routing、Kotlinx.serialization、Static Content
• 包含示例代码

将项目导入IntelliJ运行后，向http://localhost:8080或http://localhost:8080/json/kotlinx-serialization发送GET请求，返回状态码200但无响应体，Postman测试结果一致。切换为Gradle构建或Netty引擎后功能正常，当前使用JDK 17。

复现步骤 #

• 按上述配置在start.ktor.io创建新项目
• 导入IntelliJ并启动服务
• 访问http://localhost:8080即可复现问题

最小复现代码 #

pom.xml #

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>ktor-sample23</artifactId>
    <version>0.0.1</version>
    <name>ktor-sample23</name>
    <description>ktor-sample23</description>
    <properties>
        <kotlin.code.style>official</kotlin.code.style>
        <kotlin_version>2.1.0</kotlin_version>
        <ktor_version>3.0.2</ktor_version>
        <logback_version>1.4.14</logback_version>
        <slf4j_version>2.0.9</slf4j_version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <kotlin.compiler.incremental>true</kotlin.compiler.incremental>
        <main.class>com.example.ApplicationKt</main.class>
    </properties>
    <repositories>
    </repositories>
    <dependencies>
        <dependency>
            <groupId>io.ktor</groupId>
            <artifactId>ktor-server-content-negotiation-jvm</artifactId>
            <version>${ktor_version}</version>
        </dependency>
        <dependency>
            <groupId>io.ktor</groupId>
            <artifactId>ktor-server-core-jvm</artifactId>
            <version>${ktor_version}</version>
        </dependency>
        <dependency>
            <groupId>io.ktor</groupId>
            <artifactId>ktor-serialization-kotlinx-json-jvm</artifactId>
            <version>${ktor_version}</version>
        </dependency>
        <dependency>
            <groupId>io.ktor</groupId>
            <artifactId>ktor-server-host-common-jvm</artifactId>
            <version>${ktor_version}</version>
        </dependency>
        <dependency>
            <groupId>io.ktor</groupId>
            <artifactId>ktor-server-tomcat-jakarta-jvm</artifactId>
            <version>${ktor_version}</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>${logback_version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${slf4j_version}</version>
        </dependency>
        <dependency>
            <groupId>io.ktor</groupId>
            <artifactId>ktor-server-test-host-jvm</artifactId>
            <version>${ktor_version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-test-junit</artifactId>
            <version>${kotlin_version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlinx</groupId>
            <artifactId>kotlinx-coroutines-debug</artifactId>
            <version>1.6.4</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <sourceDirectory>${project.basedir}/src/main/kotlin</sourceDirectory>
        <testSourceDirectory>${project.basedir}/src/test/kotlin</testSourceDirectory>
        <resources>
            <resource>
                <directory>${project.basedir}/src/main/resources</directory>
            </resource>
        </resources>

        <plugins>
            <plugin>
                <artifactId>kotlin-maven-plugin</artifactId>
                <groupId>org.jetbrains.kotlin</groupId>
                <version>${kotlin_version}</version>
                <configuration>
                    <jvmTarget>1.8</jvmTarget>
                </configuration>
                <executions>
                    <execution>
                        <id>compile</id>
                        <phase>compile</phase>
                        <goals>
                            <goal>compile</goal>
                        </goals>
                    </execution>
                    <execution>
                        <id>test-compile</id>
                        <phase>test-compile</phase>
                        <goals>
                            <goal>test-compile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>1.2.1</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>java</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <mainClass>${main.class}</mainClass>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>2.6</version>
                <configuration>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                    <archive>
                        <manifest>
                            <addClasspath>true</addClasspath>
                            <mainClass>${main.class}</mainClass>
                        </manifest>
                    </archive>
                </configuration>
                <executions>
                    <execution>
                        <id>assemble-all</id>
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-maven-plugin</artifactId>
                <version>${kotlin_version}</version>
                <executions>
                    <execution>
                        <id>compile</id>
                        <phase>compile</phase>
                        <goals>
                            <goal>compile</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <compilerPlugins>
                        <plugin>kotlinx-serialization</plugin>
                    </compilerPlugins>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-serialization</artifactId>
                        <version>${kotlin_version}</version>
                    </dependency>
                </dependencies>
            </plugin>
        </plugins>
    </build>
</project>

Application.kt #

package com.example

import io.ktor.server.application.*
import io.ktor.server.engine.*
import io.ktor.server.tomcat.jakarta.*

fun main() {
    embeddedServer(Tomcat, port = 8080, host = "0.0.0.0", module = Application::module)
        .start(wait = true)
}

fun Application.module() {
    configureSerialization()
    configureRouting()
}

Routing.kt #

package com.example

import io.ktor.serialization.kotlinx.json.*
import io.ktor.server.application.*
import io.ktor.server.http.content.*
import io.ktor.server.plugins.contentnegotiation.*
import io.ktor.server.response.*
import io.ktor.server.routing.*

fun Application.configureRouting() {
    routing {
        get("/") {
            call.respondText("Hello World!")
        }
        // Static plugin. Try to access `/static/index.html`
        staticResources("/static", "static")
    }
}

Serialization.kt #

package com.example

import io.ktor.serialization.kotlinx.json.*
import io.ktor.server.application.*
import io.ktor.server.http.content.*
import io.ktor.server.plugins.contentnegotiation.*
import io.ktor.server.response.*
import io.ktor.server.routing.*

fun Application.configureSerialization() {
    install(ContentNegotiation) {
        json()
    }
    routing {
        get("/json/kotlinx-serialization") {
                call.respond(mapOf("hello" to "world"))
            }
    }
}

内容的提问来源于stack exchange，提问作者Rudhra Koul