Spring Boot WAR包部署至Tomcat出现HTTP 404错误求助

开发环境：IntelliJ IDEA、JDK 19、Maven、Hibernate

我尝试将Spring Boot应用打包为WAR包部署到本地Tomcat服务器，但访问时始终出现HTTP 404错误，已尝试多种方案仍未解决，求帮助。

应用核心代码 #

DemoApplication.java

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {

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

}

Controller.java

package com.example.demo;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class Controller {

    @GetMapping("/")
    public String start()
    {
        return "Hello User, have a nice day.";
    }

    @GetMapping("/hello")
    public String hello()
    {
        return "Hello User, have a nice day.";
    }

}

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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.5</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>
    <name>demo</name>
    <description>demo</description>
    <properties>
        <java.version>19</java.version>
        <tomcat.version>9.0.19</tomcat.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <finalName>demo</finalName>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

ServletInitializer.java

package com.example.demo;

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

public class ServletInitializer extends SpringBootServletInitializer {

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

}

排查与解决方案建议 #

• 核心问题：版本兼容性不匹配：Tomcat 9.x最高仅支持JDK 11，你使用的是JDK 19，版本不兼容会导致应用无法正常加载。建议降级JDK到11，或升级Tomcat到10.x（支持JDK 17及以上版本）。
• 检查访问路径：部署WAR包后，正确访问路径应为http://localhost:8080/demo/或http://localhost:8080/demo/hello，需加上WAR包的上下文路径（finalName为demo），不要直接访问Tomcat根路径。
• 查看Tomcat日志：检查logs/catalina.out或localhost.log，确认WAR包是否成功部署，是否存在类加载异常、Spring容器启动失败等报错信息。
• 验证WAR包完整性：用解压工具打开生成的WAR包，确认WEB-INF/classes下有编译后的class文件，WEB-INF/lib下包含所有依赖jar包，确保打包过程无报错。
• 规范Maven打包命令：使用mvn clean package -DskipTests命令打包，跳过测试环节避免打包中断，保证WAR包生成完整。

内容的提问来源于stack exchange，提问作者matthias