java - "java.lang.ClassNotFoundException: org.codehaus.jackson.map.ObjectMapper"在 Eclipse 火星

Question

我能够在以前版本的 Eclipse 中运行相同的 Struts 2 应用程序。

但是当我尝试在 Mars.1 中运行它时，出现以下异常:

Nov 25, 2015 1:16:56 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [jsp] in context with path [/GoogleChart] threw exception [javax.servlet.ServletException: java.lang.NoClassDefFoundError: org/codehaus/jackson/map/ObjectMapper] with root cause
java.lang.ClassNotFoundException: org.codehaus.jackson.map.ObjectMapper
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1854)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1703)

我的 POM 是这样的:

<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>AutoPlat</groupId>
  <artifactId>AutoPlat</artifactId>
  <version>0.0.5</version>
  <name>AutoPlat</name>
  <description>AutoPlat</description>
  <build>
    <sourceDirectory>src</sourceDirectory>
    <resources>
      <resource>
        <directory>src</directory>
        <excludes>
          <exclude>**/*.java</exclude>
        </excludes>
      </resource>
    </resources>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.1</version>
        <configuration>
          <source>1.7</source>
          <target>1.7</target>
        </configuration>
      </plugin>
      <plugin>
        <artifactId>maven-war-plugin</artifactId>
        <version>2.3</version>
        <configuration>
          <warSourceDirectory>WebContent</warSourceDirectory>
          <failOnMissingWebXml>false</failOnMissingWebXml>
        </configuration>
      </plugin>
    </plugins>
  </build>
  <dependencies>
    <dependency>
        <groupId>org.apache.struts</groupId>
        <artifactId>struts2-core</artifactId>
        <version>2.3.16</version>
    </dependency>

    <dependency>
        <groupId>org.codehaus.jackson</groupId>
        <artifactId>jackson-mapper-asl</artifactId>
        <version>1.9.13</version>
    </dependency>

  </dependencies>
  <dependencyManagement>

  </dependencyManagement>
  <packaging>war</packaging>
</project>

还有，web.xml:

<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee" 
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
           http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
           version="3.0" metadata-complete="true">

    <display-name>Welcome to Tomcat</display-name>
    <description>
     Welcome to Tomcat
  </description>
<!--    <servlet>
        <servlet-name>PieChartServlet</servlet-name>
        <servlet-class>chart.PieChartServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>PieChartServlet</servlet-name>
        <url-pattern>/PieChartServlet</url-pattern>
    </servlet-mapping> -->
    <filter>
        <filter-name>struts2</filter-name>
        <filter-class>
            org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter
        </filter-class>
    </filter>
    <filter-mapping>
        <filter-name>struts2</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <welcome-file-list>
        <welcome-file>DashBoard.jsp</welcome-file>
    </welcome-file-list>

</web-app>

这个错误的原因是什么？

Answer 1

原因:

java.lang.ClassNotFoundException: org.codehaus.jackson.map.ObjectMapper

Jackson在类路径中丢失

---

我猜 the underline problem是这样的:

Maven

Now that Codehaus no longer serves up Maven repositories, you will need to change your configuration.

If your configuration is not updated and you slam our redirector, then you may be served invalid JAR files with status 200 to encourage you to update your configuration.

Making Maven Work

settings.xml

In ~/.m2/settings.xml you can update the URL to be used for specific repositories.

For example:

<repositories>
  <repository>
    <id>codehaus-mule-repo</id>
    <name>codehaus-mule-repo</name>
    <url>
      https://repository-master.mulesoft.org/nexus/content/groups/public/
    </url>
    <layout>default</layout>
  </repository>
</repositories>

另请注意， Artifact has been migrated自 1.9.13 以来发展了很多，现在是 has reached 2.6.3 :

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.6.3</version>
</dependency>