如何将含MongoDB操作的Spring Boot App1作为依赖引入App2？

云上老周

2026-8-6

Spring Boot跨应用调用MongoRepository服务启动失败

我将操作MongoDB的Spring Boot App1打包为Jar作为依赖引入App2，调用其基于MongoRepository的Service方法时，App2启动报错，提示找不到PersonRepo类型的Bean。尝试过@Autowired注入App1的PersonService失败，后来通过配置类手动创建Service的Bean，仍无法解决Repo缺失问题。

错误日志

.   ____          _            __ _ _
 /\/ ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v2.7.7)

2023-01-06 22:51:27.472  INFO 13892 --- [           main] com.example.apptwo.ApptwoApplication     : Starting ApptwoApplication using Java 17.0.1 on HP with PID 13892 (C:\Users\saurabh\Desktop\apptwo\apptwo\target\classes started by saurabh in C:\Users\saurabh\Desktop\apptwo\apptwo)
2023-01-06 22:51:27.475  INFO 13892 --- [           main] com.example.apptwo.ApptwoApplication     : No active profile set, falling back to 1 default profile: "default"
2023-01-06 22:51:27.926  INFO 13892 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data MongoDB repositories in DEFAULT mode.
2023-01-06 22:51:27.939  INFO 13892 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 8 ms. Found 0 MongoDB repository interfaces.
2023-01-06 22:51:28.178  WARN 13892 --- [           main] s.c.a.AnnotationConfigApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'appTwoService': Unsatisfied dependency expressed through field 'service'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'appone': Unsatisfied dependency expressed through field 'repo'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.example.appone.repo.PersonRepo' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
2023-01-06 22:51:28.191  INFO 13892 --- [           main] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2023-01-06 22:51:28.217 ERROR 13892 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 

***************************
APPLICATION FAILED TO START
***************************

Description:

Field repo in com.example.appone.service.PersonService required a bean of type 'com.example.appone.repo.PersonRepo' that could not be found.

The injection point has the following annotations:
    - @org.springframework.beans.factory.annotation.Autowired(required=true)


Action:

Consider defining a bean of type 'com.example.appone.repo.PersonRepo' in your configuration.

相关代码

App1代码

实体类 `Person.java`

package com.example.appone.entity;

import lombok.ToString;
import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;

@Document(collection = "test1")
@ToString
public class Person {
    @Id
    private String _id;
    private String name;
    private String email;
}

Repository接口 `PersonRepo.java`

package com.example.appone.repo;

import com.example.appone.entity.Person;
import org.springframework.data.mongodb.repository.MongoRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface PersonRepo extends MongoRepository<Person, String> {
}

Service类 `PersonService.java`

package com.example.appone.service;

import com.example.appone.entity.Person;
import com.example.appone.repo.PersonRepo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

import java.util.List;

@Component
public class PersonService implements CommandLineRunner {

    @Autowired
    private PersonRepo repo;

    public List<Person> getAllTest() {
        return repo.findAll();
    }

    @Override
    public void run(String... args) throws Exception {
        System.out.println(getAllTest());
    }
}

配置文件 `application.properties`

spring.data.mongodb.uri=mongodb://localhost:27017/DB1
spring.data.mongodb.database=DB1

App2代码

配置类 `AppOneConfig.java`

package com.example.apptwo.service;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.example.appone.service.PersonService;

@Configuration
public class AppOneConfig {

    @Bean
    public PersonService appone() {
        return new PersonService();
    }
}

Service类 `AppTwoService.java`

package com.example.apptwo.service;

import com.example.appone.service.PersonService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

@Component
public class AppTwoService implements CommandLineRunner {
    
    @Autowired
    private PersonService service;

    @Override
    public void run(String... args) throws Exception {
        System.out.println(service.getAllTest());
    }
}

POM文件 `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>2.7.7</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>apptwo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>apptwo</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-mongodb</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>com.example</groupId>
            <artifactId>appone</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

解决方法

问题根源

Spring Boot默认只扫描启动类所在包及其子包的组件，App2不会自动扫描依赖包App1中的Repository和Service。
手动new PersonService()的方式绕过了Spring的依赖注入机制，导致PersonRepo无法被自动注入。

具体修复步骤

1. 扩展App2的扫描范围

修改App2的启动类，添加@EnableMongoRepositories指定扫描App1的Repository包，同时用@ComponentScan扫描App1的组件：

package com.example.apptwo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.data.mongodb.repository.config.EnableMongoRepositories;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
// 同时扫描App1和App2的Repository
@EnableMongoRepositories(basePackages = {"com.example.appone.repo", "com.example.apptwo.repo"})
// 同时扫描App1和App2的所有Spring组件
@ComponentScan(basePackages = {"com.example.appone", "com.example.apptwo"})
public class ApptwoApplication {
    public static void main(String[] args) {
        SpringApplication.run(ApptwoApplication.class, args);
    }
}

2. 删除手动创建Bean的配置类

删除AppOneConfig类，因为@ComponentScan会自动扫描到App1中被@Component注解的PersonService，Spring会自动创建Bean并完成PersonRepo的注入。

3. 配置App2的MongoDB连接

在App2的application.properties中添加MongoDB配置（可复用App1的配置）：

spring.data.mongodb.uri=mongodb://localhost:27017/DB1
spring.data.mongodb.database=DB1

4. 修正App1的打包方式

App1默认打包成可执行Jar，作为依赖引入时会有类加载问题，需修改App1的POM，生成普通Jar用于依赖：

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>
                <excludes>
                    <exclude>
                        <groupId>org.projectlombok</groupId>
                        <artifactId>lombok</artifactId>
                    </exclude>
                </excludes>
            </configuration>
            <executions>
                <execution>
                    <id>repackage</id>
                    <goals>
                        <goal>repackage</goal>
                    </goals>
                    <configuration>
                        <classifier>exec</classifier>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

修改后执行mvn clean package，会生成两个Jar：appone-0.0.1-SNAPSHOT.jar（普通Jar，用于App2依赖）和appone-0.0.1-SNAPSHOT-exec.jar（可执行Jar）。

5. 更新依赖并重启App2

重新安装App1到本地仓库（mvn install），然后更新App2的依赖，启动App2即可正常运行。

内容的提问来源于stack exchange，提问作者Saurabh Vishwakarma

如何将含MongoDB操作的Spring Boot App1作为依赖引入App2？

错误日志 #

相关代码 #

App1代码 #

实体类 Person.java

Repository接口 PersonRepo.java

Service类 PersonService.java

配置文件 application.properties

App2代码 #

配置类 AppOneConfig.java

Service类 AppTwoService.java

POM文件 pom.xml

解决方法 #

问题根源 #

具体修复步骤 #