无法使用.jar加载导入的类

Question

I currently have a java-based maven project which when run, spins up jetty server and load a web app to the localhost:4567. I want to deploy this app to a server on a CentOS virtual machine but I'm not sure where to start. CentOS currently has an Apache server running, an has maven, DB, and other dependencies are installed.

I packaged the project as a .jar but I'm currently unable to run the .jar file. I get an Exception "java.lang.NoClassDefFoundError: spark/Route" when I run the jar file via command prompt or IDE.

pom.xml looks like this:

<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.labfinder</groupId>
<artifactId>labfinder</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>

<name>LabFinder</name>
<url>http://maven.apache.org</url>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

<repositories>
    <repository>
        <id>Spark repository</id>
        <url>http://www.http://sparkjava.com/nexus/content/repositories/spark/</url>
    </repository>
</repositories>

<build>
    <plugins>
        <plugin>
            <!-- Build an executable JAR -->
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-jar-plugin</artifactId>
            <version>2.4</version>
            <configuration>
                <archive>
                    <manifest>
                        <addClasspath>true</addClasspath>
                        <mainClass>com.labfinder.Main</mainClass>
                    </manifest>
                </archive>
            </configuration>
        </plugin>
    </plugins>
</build>

<dependencies>
    <dependency>
        <groupId>org.mongodb</groupId>
        <artifactId>mongodb-driver</artifactId>
        <version>3.1.0</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>3.8.1</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>com.sparkjava</groupId>
        <artifactId>spark-core</artifactId>
        <version>2.3</version>
    </dependency>
    <dependency>
        <groupId>org.freemarker</groupId>
        <artifactId>freemarker</artifactId>
        <version>2.3.23</version>
    </dependency>
    <dependency>
        <groupId>commons-collections</groupId>
        <artifactId>commons-collections</artifactId>
        <version>3.2.1</version>
    </dependency>
</dependencies>

As far as I know I shouldn't have to put Spark Java into my class-path. Any one know whats going on here?

Answer 1

You should use the maven-assembly-plugin to build a single executable jar with dependencies included, also known as fat jar.

Instead of the maven-jar-plugin, try using the following in your pom.xml:

                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-assembly-plugin</artifactId>
                    <version>2.4.1</version>
                    <executions>
                        <execution>
                            <phase>package</phase>
                            <goals>
                                <goal>single</goal>
                            </goals>
                            <configuration>
                                <finalName>${project.artifactId}</finalName>
                                <attach>false</attach>
                                <descriptorRefs>
                                    <descriptorRef>jar-with-dependencies</descriptorRef>
                                </descriptorRefs>
                                <archive>
                                    <manifest>
                                        <mainClass>com.labfinder.Main</mainClass>
                                    </manifest>
                                </archive>
                            </configuration>
                        </execution>
                    </executions>
                </plugin>