NoClassDefFoundError春季启动Maven [英] NoClassDefFoundError spring boot maven

问题描述

我用spring boot编程REST API，它使用一些外部库，这些库通过依赖关系包含在我的pom.xml中. 如果我通过 mvn spring-boot:run 在IntelliJ中启动项目，那么一切都很好，但是如果我尝试通过 mvn package 将所有内容打包到jar中，则所有外部依赖关系都将得到解决.除了spring-boot之外的其他东西都没有.但是，相应的jarfiles被复制到jar的lib文件夹中. 因此，如果我启动jar，一切正常(回答getRequests等)，但是一旦我想初始化 FFmpegFrameGrabber 类型的变量(来自bytedeco)我收到 NoClassDefFoundError

Im programming a REST API with spring boot which uses some external libraries which are included via dependency in my pom.xml. If i start the project in IntelliJ via mvn spring-boot:run everything works just fine but if i try to package everything into a jar via mvn package all external dependecy calsses are missing except the ones of spring-boot. However, the corresponding jarfiles are copied into the lib folder of the jar. So if i Start the jar everything works just fine (answering for getRequests etc.) But as soon as i want to initialize a variable of type FFmpegFrameGrabber (which is from bytedeco) i get a NoClassDefFoundError

我的POM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>spring-boot-test</groupId>
    <artifactId>test</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.2.7.RELEASE</version>
    </parent>

    <properties>
        <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>

        <dependency>
            <groupId>org.bytedeco</groupId>
            <artifactId>javacv</artifactId>
            <version>1.1</version>
        </dependency>

    </dependencies>

    <build>
        <finalName>${project.artifactId}</finalName>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

带盖罐子的结构(一部分):
罐子
+你好
+ lib
+ META-INF
+ org
---- + springframework
---- +这里应该是bytedeco(?)

The structure of the genrerated jar (part of it):
jar
+ hello
+ lib
+ META-INF
+ org
----+ springframework
----+ HERE shoould be bytedeco (?)

预先感谢

最小(非)工作示例

package hello;

import org.bytedeco.javacv.FFmpegFrameGrabber;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.bind.annotation.RequestMapping;

@RestController
public class HelloController {

    @RequestMapping("/")
    public String index() {
        String path = "D:\\TestVideos\\1\\original.mp4";
        FFmpegFrameGrabber frameGrabber;
        System.out.println("Starting Frame Grabber for: "  + path);
        frameGrabber = new FFmpegFrameGrabber(path);
        try {
            frameGrabber.start();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return "Greetings from Spring Boot! Opening: " + path;
    }

}

还有Application.java

And the Application.java

package hello;

import java.util.Arrays;

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

@SpringBootApplication
public class Application {

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

        System.out.println("Let's inspect the beans provided by Spring Boot:");

        String[] beanNames = ctx.getBeanDefinitionNames();
        Arrays.sort(beanNames);
        for (String beanName : beanNames) {
            System.out.println(beanName);
        }
    }

}

这直接来自spring boot教程. 再来一次

This is straight from the spring boot tutorial. tanks again

推荐答案

在pom.xml <build><plugins> ... </plugins></build>部分中添加以下插件. 生成Maven项目并执行jar命令. 该插件会将您所有的依赖jar打包到最终的可执行jar中.

Add the plugin below in your pom.xml <build><plugins> ... </plugins></build> section. Build the maven project and execute the jar command. This plugin will package all your dependent jars into the final executable jar.

        <plugin>
            <artifactId>maven-assembly-plugin</artifactId>
            <version>2.6</version>
            <configuration>
                <descriptorRefs>
                    <descriptorRef>jar-with-dependencies</descriptorRef>
                </descriptorRefs>
            </configuration>
        </plugin>

此页面具有有关maven程序集插件的更多信息- https://maven.apache.org/plugins/maven-assembly-plugin/usage.html

This page has more information on maven assembly plugin - https://maven.apache.org/plugins/maven-assembly-plugin/usage.html

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