跨jar和war的Spring Boot中@Component Scan无法与@Component一起使用

Question

我以此方式在Spring Boot应用程序中拥有一个通用的jar文件，

package com.acc.api;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@SpringBootApplication
@ComponentScan(basePackages = {"com.acc.api","service"})
public class ApicoreApplication {

    public static void main(String[] args) {
        ApplicationContext applicationContext = SpringApplication.run(ApicoreApplication.class, args);

        for (String name: applicationContext.getBeanDefinitionNames()) {
            System.out.println(name);
        }
    }

}

其中的组件是

package com.acc.api.core.utils;

import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
public class AccUtil {

    @Autowired
    private WebServiceEngine engine;

}

其中WebServiceEngine是我调用的第三方API。

我的pom条目就是这样，

<?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>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.2.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.acc.api</groupId>
    <artifactId>apicore</artifactId>
    <version>0.0.1</version>
    <name>apicore</name>
    <description>apicore</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-mongodb</artifactId>
        </dependency>
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.json</groupId>
            <artifactId>json</artifactId>
            <version>20090211</version>
        </dependency>
        <dependency>
            <groupId>org.apache.tomcat</groupId>
            <artifactId>tomcat-util</artifactId>
            <version>8.5.23</version>
        </dependency>
        <dependency>
             <groupId>WebServiceEngine</groupId>
            <artifactId>WebServiceEngine</artifactId>
            <version>7.10.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.8.1</version>
        </dependency>
    </dependencies>

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

</project>

到此为止，项目正在编译并且正在目标文件夹中创建jar。

现在我以这种方式在另一个spring boot war文件中使用这个jar，

<?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.acc.api</groupId>
    <artifactId>maintenance</artifactId>
    <packaging>war</packaging>

    <parent>
        <groupId>com.acc.api</groupId>
        <artifactId>test</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </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-data-mongodb</artifactId>
        </dependency>
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>com.jayway.jsonpath</groupId>
            <artifactId>json-path</artifactId>
        </dependency>

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
        </dependency>

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

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.json</groupId>
            <artifactId>json</artifactId>
            <version>20090211</version>
        </dependency>               
    <dependency>
                <groupId>com.acc.api</groupId>
                <artifactId>apicore</artifactId>
                <version>0.0.1</version>
            </dependency>

        <dependency>
            <groupId>org.apache.tomcat</groupId>
            <artifactId>tomcat-util</artifactId>
            <version>8.5.23</version>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.8.1</version>
        </dependency>
    </dependencies>

    <build>
        <finalName>maintenance</finalName>
        <plugins>
            <plugin>
                <artifactId>maven-war-plugin</artifactId>
                <configuration>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                </configuration>
            </plugin>
            <plugin>
                <artifactId>maven-resources-plugin</artifactId>
                <version>3.1.0</version>
                <executions>
                    <execution>
                        <id>copy war</id>
                        <phase>package</phase>
                        <goals>
                            <goal>copy-resources</goal>
                        </goals>
                        <configuration>
                            <outputDirectory></outputDirectory>
                            <filtering>true</filtering>
                            <overwrite>true</overwrite>
                            <resources>
                                <resource>
                                    <directory>${project.build.directory}</directory>
                                    <includes>
                                        <include>${project.build.finalName}.war</include>
                                    </includes>
                                </resource>
                            </resources>
                        </configuration>
                    </execution>
                </executions>
            </plugin>

            <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <version>1.5.7.RELEASE</version>
            <executions>
                <execution>
                    <goals>
                        <goal>repackage</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <includeSystemScope>true</includeSystemScope>
            </configuration>
        </plugin>

        </plugins>
    </build>

</project>

我在war文件中的springboot类是这样的，

package com.acc.api;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;

    @SpringBootApplication
    public class MaintenanceApplication {

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

    }

    package com.acc.api;

    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(MaintenanceApplication.class);
        }

    }

在这个MaintenanceApplication战争文件中，我在jar上方使用该控制器的实际控制器是

    package com.acc.api.controller;

    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.context.annotation.Import;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RestController;
    import com.fasterxml.jackson.databind.ObjectMapper;

    import com.acc.api.core.utils.AccUtil;

    @Import({AccUtil.class})
    @RestController
    @RequestMapping("/STATUS")
    public class StatusController {

        private static Logger logger = LoggerFactory.getLogger(StatusController.class);

        @Autowired
        private AccUtil accUtil;

        @Autowired
        private ObjectMapper objMapper;

        @RequestMapping(method=RequestMethod.GET, value="/fetchStatus")
        public String getStatus(@PathVariable String processId){
            String status = "";
            try {           
                    status =  accUtil.getStats();
                    return status;
            }   
            catch (Exception e) {
                e.printStackTrace();
                return null;
            }
        }
    }

IDE没有显示任何错误，但是在进行mvn clean install时出现了构建错误。

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.0:compile (default-compile) on project maintenance: Compilation failure: Compilation failure: 
[ERROR] /src/main/java/com/acc/hpi/controller/MSRController.java:[13,30] package com.acc.api.core.utils does not exist
[ERROR]   symbol:   class AccUtils

有人可以在这方面帮助我吗？

谢谢。

Answer 1

使用Spring Boot时，spring-boot-maven-plugin将重新打包并重组生成的jar文件。此jar文件不能用作其他应用程序中的依赖项。取而代之的是，您需要指示spring-boot-maven-plugin重新打包jar并保留原始工件（并将两者都发布到您的maven存储库中）。

《 Spring Boot参考指南》中有一个special section关于如何执行此操作。

如果您的jar仅是一个依赖项，并且本身不能运行/执行，则只需删除spring-boot-maven-plugin并生成一个常规jar。

Answer 2

您已在com.acc.api.core.utils.AccUtil类中导入StatusController类两次：

import com.acc.api.core.utils.AccUtil;

@Import({AccUtil.class})

删除其中之一，然后重试。