com/fasterxml/jackson/databind/ObjectMapper 与 Maven 的 NoClassDefFoundError [英] NoClassDefFoundError of com/fasterxml/jackson/databind/ObjectMapper with Maven

问题描述

这是一个与此处类似的问题，不幸的是尚未解决.

This is a similar question as the one here, which is unfortunately unresolved yet.

如果你想调试代码，这里是GitHub repo.

If you want to debug the code, here is the GitHub repo.

我为 ObjectMapper 得到了以下 NoClassDefFoundError，尽管我已经将相关的依赖添加到了 Mave pom.xml.

I got the following NoClassDefFoundError for ObjectMapper though I have added the related dependency to Mave pom.xml.

Exception in thread "main" java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/ObjectMapper
    at demo.DemoMain.main(DemoMain.java:10)
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.databind.ObjectMapper
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 1 more

这里是源码DemoMain.java

package demo;

import com.fasterxml.jackson.databind.ObjectMapper;

public class DemoMain {
    public static void main(String[] args) {
        System.out.println("Start");
        ObjectMapper mapper = new ObjectMapper();
        System.out.println("End");
    }
}

这是我的pom.xml

<?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.example</groupId>
<artifactId>Demo</artifactId>
<version>1.0-SNAPSHOT</version>

<dependencies>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-annotations</artifactId>
        <version>2.8.3</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>2.8.3</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.8.3</version>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-jar-plugin</artifactId>
            <version>3.0.0</version>
            <configuration>
                <archive>
                    <index>true</index>
                    <manifest>
                        <addClasspath>true</addClasspath>
                        <mainClass>demo.DemoMain</mainClass>
                    </manifest>
                </archive>
            </configuration>
        </plugin>
    </plugins>
</build>

我编译并运行应用程序

mvn clean install
java -jar target/Demo-1.0-SNAPSHOT.jar

推荐答案

正如我在这里

默认的 maven 插件不会构建带有依赖项的胖 jar.

The default maven plugin doesn't build a fat jar with dependencies.

要构建与其依赖项捆绑在一起的 jar 以便我们可以使用 java -jar 执行它，我们可以使用 maven-assembly-plugin，它打包了名为 xxx-jar-with-dependencies.jar 的 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.

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>

现在你应该可以用

java -jar xxx-jar-with-dependencies.jar

这篇关于com/fasterxml/jackson/databind/ObjectMapper 与 Maven 的 NoClassDefFoundError的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！