使用 Spring MVC 的 Maven jackson 依赖项问题

Question

我是 spring mvc 以及使用 maven 的新手，我在网络上的其他任何地方都找不到解决方案。基本上，当尝试在 Web 上运行我的 java 应用程序时，会引发异常。 “org.springframework.beans.factory.BeanCreationException：在 ServletContext 资源 [/WEB-INF/config/servlet-config.xml] 中定义名称为 'org.springframework.web.servlet.view.ContentNegotiatingViewResolver#0' 创建 bean 时出错： bean 初始化失败；嵌套异常是 java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/ObjectMapper" 但是我检查了我的 Maven 依赖项，看起来我需要的所有依赖项都在那里。这是我的 Maven 文件

<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/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>tjb</groupId>
  <artifactId>MetovaCars</artifactId>
  <packaging>war</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>MetovaCars Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>4.2.3.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>com.sparkjava</groupId>
        <artifactId>spark-core</artifactId>
        <version>2.2</version>
    </dependency>
    <dependency>
        <groupId>com.sparkjava</groupId>
        <artifactId>spark-template-freemarker</artifactId>
        <version>2.0.0</version>
    </dependency>
    <dependency>
        <groupId>org.postgresql</groupId>
        <artifactId>postgresql</artifactId>
        <version>9.4-1201-jdbc4</version>
    </dependency>
    <dependency>
        <groupId>com.heroku.sdk</groupId>
        <artifactId>heroku-jdbc</artifactId>
        <version>0.1.1</version>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>servlet-api</artifactId>
        <version>2.5</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-oxm</artifactId>
        <version>3.2.0.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-validator</artifactId>
        <version>4.2.0.Final</version>
    </dependency>
    <dependency>
        <groupId>org.codehaus.jackson</groupId>
        <artifactId>jackson-mapper-asl</artifactId>
        <version>1.9.13</version>
    </dependency>
    <dependency>
        <groupId>com.thoughtworks.xstream</groupId>
        <artifactId>xstream</artifactId>
        <version>1.3.1</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>2.6.3</version>
    </dependency>
  </dependencies>
  <build>
    <finalName>MetovaCars</finalName>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>2.5.1</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
          <optimize>true</optimize>
          <debug>true</debug>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-dependency-plugin</artifactId>
        <version>2.4</version>
        <executions>
          <execution>
            <id>copy-dependencies</id>
            <phase>package</phase>
            <goals><goal>copy-dependencies</goal></goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

这是它所引用的 bean。

<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
    <property name="order" value="1" />
    <property name="contentNegotiationManager">
        <bean class="org.springframework.web.accept.ContentNegotiationManager">
            <constructor-arg>
                <bean class="org.springframework.web.accept.PathExtensionContentNegotiationStrategy">
                    <constructor-arg>
                        <map>
                            <entry key="json" value="application/json" />
                            <entry key="xml" value="application/xml" />
                        </map>
                    </constructor-arg>
                </bean>
            </constructor-arg>
        </bean>
    </property>
    <property name="defaultViews">
        <list>
            <bean class="org.springframework.web.servlet.view.json.MappingJackson2JsonView"></bean>
            <bean class="org.springframework.web.servlet.view.xml.MarshallingView">
                <constructor-arg>
                    <bean class="org.springframework.oxm.xstream.XStreamMarshaller">
                        <property name="autodetectAnnotations" value="true"></property>
                    </bean>
                </constructor-arg>
            </bean>
        </list>
    </property>
</bean>

我被难住了。

Answer 1

根据我在您的pom.xml 中看到的情况，您正在混合杰克逊依赖项。我的意思是这些行：

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

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

您正在使用旧版本的 jackson artifact com.codehaus.jackson 和新版本 com.fasterxml.jackson.core，您应该使用其中一个以及所有必需的依赖项（核心、映射器、数据绑定）。有关迁移的更多信息，请参阅here。

将它们替换为。使用相同的版本：

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

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

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

如果您有其他问题，请随时联系。