java.lang.ClassNotFoundException / NoClassDefFoundError for com/fasterxml/jackson/databind/ObjectMapper with Maven
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java.lang.ClassNotFoundException / NoClassDefFoundError for com/fasterxml/Hymanson/databind/ObjectMapper with Maven
提问by ur-vogel
I get the following error when trying to run a java program that uses Hymanon's ObjectMapper class:
尝试运行使用 Hymanon 的 ObjectMapper 类的 Java 程序时，出现以下错误：
Exception in thread "main" java.lang.NoClassDefFoundError: com/fasterxml/Hymanson/databind/ObjectMapper
at com.inin.dynamotransfer.DynamoTransfer.importData(DynamoTransfer.java:133)
at com.inin.dynamotransfer.DynamoTransfer.main(DynamoTransfer.java:67)
Caused by: java.lang.ClassNotFoundException: com.fasterxml.Hymanson.databind.ObjectMapper
at java.net.URLClassLoader.run(URLClassLoader.java:366)
at java.net.URLClassLoader.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
... 2 more
I have the Hymanson annotations, databind (which contains ObjectMapper), and core JARs in my Maven repository under ~/.m2/repository/com/fasterxml/Hymanson/core/Hymanson-[packagename]/2.4.0. here's the dependencies section of my pom.xml:
我在 ~/.m2/repository/com/fasterxml/Hymanson/core/Hymanson-[packagename]/2.4.0 下的 Maven 存储库中有 Hymanson 注释、数据绑定（包含 ObjectMapper）和核心 JAR。这是我的 pom.xml 的依赖项部分：
<dependencies>
<dependency>
<groupId>com.fasterxml.Hymanson.core</groupId>
<artifactId>Hymanson-annotations</artifactId>
<version>2.4.0</version>
</dependency>
<dependency>
<groupId>com.fasterxml.Hymanson.core</groupId>
<artifactId>Hymanson-databind</artifactId>
<version>2.4.0</version>
</dependency>
<dependency>
<groupId>com.fasterxml.Hymanson.core</groupId>
<artifactId>Hymanson-core</artifactId>
<version>2.4.0</version>
</dependency>
</dependencies>
here's my CLASSPATH:
这是我的类路径：
:/Users/myusername/Library/Java/Extensions:/Library/Java/Extensions:/Users/myusername/.m2/repository
so Maven knows all about these JARs - where to get em, where to put em, etc. - but java itself can't seem to find the classes I need. what am I doing wrong?? thanks!
所以 Maven 知道所有关于这些 JAR 的信息——从哪里得到它们，把它们放在哪里等等——但是 java 本身似乎无法找到我需要的类。我究竟做错了什么？？谢谢！
回答by Oleksii Kyslytsyn
try to redo maven lifecycle goals:
尝试重做 maven 生命周期目标：
mvn clean install -U
回答by hackjutsu
The default maven plugin doesn't build a fat jar with dependencies.
默认的 maven 插件不会构建具有依赖项的胖 jar。
To build a jar bundled with its dependencies so that we can execute it with java -jar, we can use maven-assembly-plugin, which packages the jar with the name xxx-jar-with-dependencies.jar.
要构建一个与其依赖项捆绑在一起的 jar，以便我们可以使用 执行它java -jar，我们可以使用maven-assembly-plugin，它将 jar 打包为名称xxx-jar-with-dependencies.jar。
Here is a sample pom.xml
这是一个示例 pom.xml
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>3.0.0</version>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>com.example.yourMain</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-assembly</id> <!-- this is used for inheritance merges -->
<phase>package</phase> <!-- bind to the packaging phase -->
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
Now you should be able to run your jar with
现在你应该能够运行你的罐子了
java -jar xxx-jar-with-dependencies.jar
