1、先启动好

参考我的spring boot学习第一篇文档：spring boot 1.5.x版本启动接口服务_veminhe的博客-CSDN博客

需要改动2个地方

pom.xml里面

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

 启动后，发现使用http://localhost:8080/demo/api

访问不行

访问http://localhost:8080/api

却是好的。 

无意中看到阿里云开发者平台资料

Spring 全家桶之 Spring Boot 2.6.4（二）- Configuration（Part B）（下）-阿里云开发者社区

注意观察Tomcat started on port(s): 8080 (http) with context path '/demo'这样的启动日志

配置工程上下文根的配置，应该是server.servlet.context-path=/demo这样的，改了后，重启服务

 

 访问http://localhost:8080/demo/api

 接口正常

2、贴上代码

2.1pom.xml文件内容如下：

<?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.hmblogs</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.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-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>




</project>

2.2application.properties文件内容如下：

server.port=8080
server.servlet.context-path=/demo

2.3HelloController.java文件内容如下：

package com.example.demo;

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

@RestController
public class HelloController {

    @RequestMapping("/api")
    public String index() {
        return "Greetings from Spring Boot!";
    }

}

2.4DemoApplication.java文件内容如下：

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);
    }

}