Question

I wanted to download webpage using Apache Camel, and sadly my efforts were stopped by awful wall of errors, all of which seem to be caused by:

java.lang.NoClassDefFoundError: javax/servlet/ServletInputStream

I find it very confusing, as it looks like a class from standard library.

I created project in eclipse, and in referenced libraries I have:

• slf4j-api-1.6.4.jar
• slf4j-simple-1.6.4.jar
• camel-core-2.9.1.jar
• camel-http4-2.9.1.jar

Code of class that is supposed to do the job:

package camelexample;

import org.apache.camel.CamelContext;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.impl.DefaultCamelContext;

public class HttpDownload {
  public static void main(String[] args) throws Exception{
    System.out.print("download");

    CamelContext context = new DefaultCamelContext();
    context.addRoutes(new RouteBuilder(){
      public void configure(){
        from("http://www.ii.uni.wroc.pl/~gst/").to("file:data/webpage.html");
      }
    });

    context.start();
    Thread.sleep(10);
    context.stop();
  }
}

In order to run the project, I just use eclipse “run” button. What am I doing wrong?

Answer 1

You need to add a JAR with the servlet API, for example this JAR

org.apache.geronimo.specs:geronimo-servlet_2.5_spec:jar:1.1.2:compile

You can find it in central maven repo at:
http://repo2.maven.org/maven2/org/apache/geronimo/specs/geronimo-servlet_2.5_spec/1.1.2/

And then add that JAR to your classpath.

And since you use camel-http4, which uses Apache Http Client 4.x you need its dependencies as well

[INFO] +- org.apache.httpcomponents:httpclient:jar:4.1.3:compile
[INFO] |  +- org.apache.httpcomponents:httpcore:jar:4.1.4:compile
[INFO] |  +- commons-logging:commons-logging:jar:1.1.1:compile
[INFO] |  \- commons-codec:commons-codec:jar:1.4:compile