Vaadin+Spring Boot替换Tomcat为Undertow遇ERR_CONNECTION_CLOSED问题

问题描述 #

将Vaadin+Spring Boot项目中的Tomcat替换为Undertow后，控制台无报错信息，但访问REST API或Vaadin视图时，浏览器仅提示“ERR_CONNECTION_CLOSED”错误，切回Tomcat则一切正常。

原build.gradle内容 #

configurations.all {
    exclude group: 'org.springframework.boot', module:'spring-boot-starter-tomcat'
}

dependencies {
    implementation "com.vaadin:vaadin-core:$vaadinVersion"
    implementation "org.springframework.boot:spring-boot-starter-security:$springBootVersion"
    implementation("org.springframework.boot:spring-boot-starter-web:$springBootVersion") {
        exclude group: 'com.fasterxml.jackson.core'
        exclude group: 'com.fasterxml.jackson.datatype'
        exclude group: 'com.fasterxml.jackson.module'
        exclude group: 'org.springframework.boot', module: 'spring-boot-starter-tomcat'
        exclude module: 'spring-boot-starter-tomcat'
        exclude group: 'org.apache.tomcat.embed'
    }

    implementation("org.springframework.boot:spring-boot-starter-undertow:$springBootVersion")

    implementation ("org.springframework.boot:spring-boot-starter-parent:$springBootVersion") {
//        exclude module: 'spring-boot-starter-tomcat'
    }
    implementation "org.springframework.boot:spring-boot-starter-mail:$springBootVersion"
    implementation "org.springframework.boot:spring-boot-configuration-processor:$springBootVersion"
    implementation("com.vaadin:vaadin-spring-boot-starter:$vaadinVersion")
    implementation ("com.vaadin:vaadin-spring-boot-starter:$vaadinVersion")

    implementation ("com.vaadin:vaadin-bom:${vaadinVersion}") {
        exclude group: 'org.springframework.boot', module:'spring-boot-starter-tomcat'
    }

    implementation 'com.google.code.gson:gson:2.10.1'

    implementation "org.springframework.boot:spring-boot-starter-data-jpa:$springBootVersion"
}

核心问题与修复步骤 #

1. 修正依赖配置中的错误 #

原配置存在多处不合理的依赖声明，这是导致连接失败的核心原因：

• 错误将spring-boot-starter-parent作为implementation依赖：parent是用来管理项目依赖版本和插件的，应在build.gradle顶部声明，而非作为业务依赖导入
• 重复添加vaadin-spring-boot-starter：重复依赖可能导致版本冲突
• 错误导入vaadin-bom：BOM是版本管理平台，需用platform方式导入，而非implementation
• 过度排除Jackson依赖：Jackson是Spring Web的核心依赖，无特殊需求不应排除，否则会导致请求处理失败

2. 修正后的build.gradle示例 #

plugins {
    id 'org.springframework.boot' version "${springBootVersion}"
    id 'io.spring.dependency-management' version '1.1.4'
    id 'com.vaadin' version "${vaadinVersion}"
}

// 正确声明Spring Boot Parent
parent {
    group 'org.springframework.boot'
    name 'spring-boot-starter-parent'
    version "${springBootVersion}"
}

// 全局排除Tomcat依赖
configurations.all {
    exclude group: 'org.springframework.boot', module: 'spring-boot-starter-tomcat'
}

dependencies {
    // 用platform导入Vaadin BOM管理版本
    implementation platform("com.vaadin:vaadin-bom:${vaadinVersion}")
    implementation "com.vaadin:vaadin-core"
    implementation "com.vaadin:vaadin-spring-boot-starter"

    implementation "org.springframework.boot:spring-boot-starter-security"
    // 仅排除Web Starter中的Tomcat依赖
    implementation("org.springframework.boot:spring-boot-starter-web") {
        exclude group: 'org.springframework.boot', module: 'spring-boot-starter-tomcat'
    }
    // 导入Undertow Starter
    implementation "org.springframework.boot:spring-boot-starter-undertow"

    implementation "org.springframework.boot:spring-boot-starter-mail"
    implementation "org.springframework.boot:spring-boot-configuration-processor"
    implementation 'com.google.code.gson:gson:2.10.1'
    implementation "org.springframework.boot:spring-boot-starter-data-jpa"
}

3. 额外排查步骤 #

如果修正依赖后问题仍存在，检查以下内容：

• 确认Undertow启动状态：启动后查看控制台，是否有类似Undertow started on port(s) 8080 (http)的日志，确认服务正常监听端口
• 端口占用检查：用netstat -ano | findstr :8080（Windows）或lsof -i :8080（Linux/Mac）检查端口是否被其他程序占用
• SSL配置验证：如果项目启用HTTPS，确保application.properties中的Undertow SSL配置正确，包括密钥存储路径、密码等
• Spring Security放行规则：确保Security配置中放行Vaadin的核心路径，比如/VAADIN/**、/frontend/**、/login、/logout等，避免拦截正常请求
• Vaadin Push配置：若使用Push功能，确认Undertow的WebSocket支持正常（spring-boot-starter-undertow已默认包含WebSocket模块）

内容的提问来源于stack exchange，提问作者Jason The Dynamite