Issue: java.lang.UnsupportedClassVersionError: org/glassfish/jersey/servlet/ServletContainer

Question

I have written a RESTful web services. Below is my maven dependencies.

<dependency>
        <groupId>org.glassfish.jersey.core</groupId>
        <artifactId>jersey-server</artifactId>
        <version>2.17</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish.jersey.containers</groupId>
        <artifactId>jersey-container-servlet-core</artifactId>
        <version>2.17</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <version>1.5.6</version>
    </dependency>
    <dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
        <version>2.3.1</version>
    </dependency>
    <dependency>
        <groupId>commons-logging</groupId>
        <artifactId>commons-logging</artifactId>
        <version>1.1.3</version>
    </dependency>
    <dependency>
        <groupId>commons-io</groupId>
        <artifactId>commons-io</artifactId>
        <version>2.2</version>
    </dependency>
    <dependency>
        <groupId>commons-codec</groupId>
        <artifactId>commons-codec</artifactId>
        <version>1.9</version>
    </dependency>
    <dependency>
        <groupId>javax.activation</groupId>
        <artifactId>activation</artifactId>
        <version>1.1.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>4.3.6</version>
    </dependency>
    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpcore</artifactId>
        <version>4.3.3</version>
    </dependency>
    <dependency>
        <groupId>org.jboss.resteasy</groupId>
        <artifactId>jaxrs-api</artifactId>
        <version>3.0.12.Final</version>
    </dependency>
    <dependency>
        <groupId>org.jboss.spec.javax.annotation</groupId>
        <artifactId>jboss-annotations-api_1.1_spec</artifactId>
        <version>1.0.1.Final</version>
    </dependency>
    <dependency>
        <groupId>net.jcip</groupId>
        <artifactId>jcip-annotations</artifactId>
        <version>1.0</version>
    </dependency>
    <dependency>
        <groupId>org.jboss.resteasy</groupId>
        <artifactId>resteasy-client</artifactId>
        <version>3.0.12.Final</version>
    </dependency>
    <dependency>
        <groupId>org.jboss.resteasy</groupId>
        <artifactId>resteasy-jaxrs</artifactId>
        <version>3.0.12.Final</version>
    </dependency>
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.14</version>
    </dependency>

Below is my web.xml

<servlet>
<servlet-name>Jersey REST Service</servlet-name>
<servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
<init-param>
  <param-name>jersey.config.server.provider.packages</param-name>
  <param-value>com.service</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
  <servlet-mapping>
<servlet-name>Jersey REST Service</servlet-name>
<url-pattern>/rest/*</url-pattern>
  </servlet-mapping>

I have pointed my JRE to jre6 and the compiler version to 1.6 in my eclipse. Rest Web Services are working perfectly.

I export as WAR and put the WAR file in webapps folder of tomcat and deploy. It is getting deployed. Issue is coming when I invoke the Web service, it is throwing the following error.

java.lang.UnsupportedClassVersionError: org/glassfish/jersey/servlet/ServletContainer : Unsupported major.minor version 51.0 (unable to load class org.glassfish.jersey.servlet.ServletContainer)
org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:2961)
org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:1210)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1690)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)

Tomcat version is 7 and JDK is 1.6 and JRE is 6. I understand that error is coming because of version problem.

How can I fix this? Anyone pls help me with this.

Answer 1

Your jersey lib doesn't support 1.6 Java. Either see if there's a jersey build that works with 1.6, or upgrade your Java.

UPDATE

Java 1.6 is supported in Jersey 2.6 and below. Jersey 2.7 and later is compiled with Java 7.