ElasticsearchClassLoader

The purpose of this project is to demonstrate how an application can work with both elasticsearch 1.x and 2.x client jars

Approach

• MainProject:

  • MainClass.java (which executes business logic)

• ESCommon:

  • ElasticSearchInterface

• ESv1:

  • ElasticSearchV1 implements ElasticSearchInterface

• ESv2:

  • ElasticSearchV2 implements ElasticSearchInterface

• How to execute the class:

  • java -cp MainProject.jar;ESCommon.jar MainClass
  • //Do not put ESv1 or ESv2 into the parent classloader classpath

• MainClass Logic:

  	public static void main(String[] args) throws Exception {
        ClassLoader loader1 = new URLClassLoader(new URL[] {new File("..\\ESv1\\target\\ESv1-0.0.1-SNAPSHOT.jar").toURL()});
        ClassLoader loader2 = new URLClassLoader(new URL[] {new File("..\\ESv2\\target\\ESv2-0.0.1-SNAPSHOT.jar").toURL()});
  
        Class<?> c1 = loader1.loadClass("com.atul.esloader.ElasticSearchV1");
        Class<?> c2 = loader2.loadClass("com.atul.esloader.ElasticSearchV2");
  
        ElasticSearchInterface es1 = (ElasticSearchInterface) c1.newInstance();
        ElasticSearchInterface es2 = (ElasticSearchInterface) c2.newInstance();
  
        es1.search(null); // Queries ElasticSearch1.x
        es2.search(null); // Queries ElasticSearch2.x
    }
  

Output

<ElasticsearchClassLoader\MainProject> java -cp ..\ESCommon\target\ESCommon-0.0.1-SNAPSHOT.jar;target\MainProject-0.0.1-SNAPSHOT.jar com.atul.esloader.MainClass
Connected to elasticsearch v1
Got 8 hits

Connected to elasticsearch v2
Got 4 hits