Error: Unable to initialize main class Caused by: java.lang.NoClassDefFoundError: org/bson/conversions/Bson

Question

https://github.com/Gjonathan252/AutoPart-Java-Database-w-MongoDB

这是我第一次使用 maven，我正在尝试运行我程序的 .jar，但是当我运行.

时，命令提示符中一直出现此错误

java -jar autopartsjavamongodb-1.0-SNAPSHOT.jar

结果：

Error: Unable to initialize main class com.example.autopartsjavamongodb.main
Caused by: java.lang.NoClassDefFoundError: org/bson/conversions/Bson

Java 程序使用 mongodb 依赖项，当我运行 IDE 上的程序或在命令上使用这个长命令时，它们似乎都在工作提示。

"C:\Program Files\Java\jdk-16.0.2\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2021.2\lib\idea_rt.jar=63226:C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2021.2\bin" -Dfile.encoding=UTF-8 -classpath "D:\Computer Science Lessons\AutoPart Java Database w MongoDB\target\classes;C:\Users\gjona\.m2\repository\org\mongodb\mongodb-driver-sync.3.1\mongodb-driver-sync-4.3.1.jar;C:\Users\gjona\.m2\repository\org\mongodb\bson.3.1\bson-4.3.1.jar;C:\Users\gjona\.m2\repository\org\mongodb\mongodb-driver-core.3.1\mongodb-driver-core-4.3.1.jar" com.example.autopartsjavamongodb.main

这就是 pom.xml 文件的样子。我不认为我遗漏了任何缺陷，因为我能够运行它在 IDE.

<modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>autopartsjavamongodb</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <properties>
        <maven.compiler.release>11</maven.compiler.release>
        <maven.compiler.source>16</maven.compiler.source>
        <maven.compiler.target>16</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.mongodb</groupId>
            <artifactId>mongodb-driver-sync</artifactId>
            <version>4.0.5</version>
        </dependency>
        <dependency>
            <groupId>org.mongodb</groupId>
            <artifactId>mongodb-driver-sync</artifactId>
            <version>4.3.1</version>
        </dependency>
        <dependency>
            <groupId>org.mongodb</groupId>
            <artifactId>bson</artifactId>
            <version>4.0.5</version>
        </dependency>
    </dependencies>
    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.8.1</version>
                </plugin>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-jar-plugin</artifactId>
                    <configuration>
                        <archive>
                            <manifest>
                                <mainClass>com.example.autopartsjavamongodb.main</mainClass>
                            </manifest>
                        </archive>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>

Answer 1

通常情况下，当我们将项目打包成jar文件时，jar文件中并不包含其依赖项，因此需要将依赖项jar文件包含在类路径中。实现这一目标的一种方法是使用 maven-assembly-plugin

这样一来，所有的依赖jar都会打包在一个jar中。

pom.xml 例子

            `<plugin>
                <artifactId>maven-assembly-plugin</artifactId>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                    <archive>
                        <manifest>
                            <addClasspath>true</addClasspath>
                            <classpathPrefix>libs/</classpathPrefix>
                            <mainClass>com.example.autopartsjavamongodb.main</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>`

另请注意，pluginManagement 标签用于在您的父 POM 中定义插件版本，在您的情况下，您不应包含 pluginManagement 标签

Error: Unable to initialize main class Caused by: java.lang.NoClassDefFoundError: org/bson/conversions/Bson

Error: Unable to initialize main class Caused by: java.lang.NoClassDefFoundError: org/bson/conversions/Bson

java

jar

executable-jar

mongodb

bson