Spring Boot 2.0部署Tomcat7报错：缺失ServletWebServerFactory bean无法启动上下文

Alright, let's tackle this problem head-on. That error you're seeing happens because of a few key mismatches between Spring Boot 2.0's defaults and what Tomcat 7 supports. Here's how to fix it step by step:

1. Fix Servlet Version Compatibility #

Spring Boot 2.0 ships with Servlet API 3.1 by default, but Tomcat 7 only supports up to Servlet 3.0. You need to override this in your pom.xml to avoid compatibility issues:

<properties>
    <servlet-api.version>3.0.1</servlet-api.version>
</properties>

<dependencies>
    <!-- Override Servlet API version -->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>${servlet-api.version}</version>
        <scope>provided</scope>
    </dependency>
</dependencies>

2. Switch to WAR Packaging & Exclude Built-in Tomcat #

Spring Boot apps default to JAR packaging with an embedded Tomcat, but to deploy to an external Tomcat 7, you need to switch to WAR and exclude the embedded container:

<!-- Update packaging type -->
<packaging>war</packaging>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <!-- Exclude embedded Tomcat -->
        <exclusions>
            <exclusion>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-tomcat</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

    <!-- Add Tomcat 7 servlet API as provided -->
    <dependency>
        <groupId>org.apache.tomcat</groupId>
        <artifactId>tomcat-servlet-api</artifactId>
        <version>7.0.96</version> <!-- Use a stable Tomcat 7 version -->
        <scope>provided</scope>
    </dependency>
</dependencies>

3. Adjust Your Application Entry Point #

Your main application class needs to extend SpringBootServletInitializer so that the external Tomcat can bootstrap your Spring Boot app properly. Update it like this:

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;

@SpringBootApplication
public class DemoApplication extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(DemoApplication.class);
    }

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

4. Use the Correct Build & Deployment Workflow #

• Stop using mvn spring-boot:run (this command relies on the embedded Tomcat which you've excluded, hence the error).
• Instead, run mvn clean package to build the WAR file.
• Copy the generated WAR from the target directory into Tomcat 7's webapps folder.
• Start Tomcat 7, and it will deploy your app automatically.

These changes should resolve the ServletWebServerFactory bean missing error and get your Spring Boot 2.0 app running on Tomcat 7 smoothly.

内容的提问来源于stack exchange，提问作者Ante Ereš