import org.apache.solr.handler.clustering.ClusteringEngine; //导入依赖的package包/类
@Test
public void testDefaultEngineOrder() throws Exception {
  ClusteringComponent comp = (ClusteringComponent) h.getCore().getSearchComponent("clustering-name-default");
  Map<String,SearchClusteringEngine> engines = getSearchClusteringEngines(comp);
  assertEquals(
      Lists.newArrayList("stc", "default", "mock"),
      Lists.newArrayList(engines.keySet()));
  assertEquals(
      LingoClusteringAlgorithm.class,
      ((CarrotClusteringEngine) engines.get(ClusteringEngine.DEFAULT_ENGINE_NAME)).getClusteringAlgorithmClass());
}
 

import org.apache.solr.handler.clustering.ClusteringEngine; //导入依赖的package包/类
@Test
public void testDeclarationEngineOrder() throws Exception {
  ClusteringComponent comp = (ClusteringComponent) h.getCore().getSearchComponent("clustering-name-decl-order");
  Map<String,SearchClusteringEngine> engines = getSearchClusteringEngines(comp);
  assertEquals(
      Lists.newArrayList("lingo", "stc", "mock", "default"),
      Lists.newArrayList(engines.keySet()));
  assertEquals(
      LingoClusteringAlgorithm.class,
      ((CarrotClusteringEngine) engines.get(ClusteringEngine.DEFAULT_ENGINE_NAME)).getClusteringAlgorithmClass());
}
 

import org.apache.solr.handler.clustering.ClusteringEngine; //导入依赖的package包/类
@Test
public void testDeclarationNameDuplicates() throws Exception {
  ClusteringComponent comp = (ClusteringComponent) h.getCore().getSearchComponent("clustering-name-dups");
  Map<String,SearchClusteringEngine> engines = getSearchClusteringEngines(comp);
  assertEquals(
      Lists.newArrayList("", "default"),
      Lists.newArrayList(engines.keySet()));
  assertEquals(
      MockClusteringAlgorithm.class,
      ((CarrotClusteringEngine) engines.get(ClusteringEngine.DEFAULT_ENGINE_NAME)).getClusteringAlgorithmClass());
}
 

import org.apache.solr.handler.clustering.ClusteringEngine; //导入依赖的package包/类
/**
 * Setup the default clustering engine.
 * @see "https://issues.apache.org/jira/browse/SOLR-5219"
 */
private static <T extends ClusteringEngine> void setupDefaultEngine(String type, LinkedHashMap<String,T> map) {
  // If there's already a default algorithm, leave it as is.
  if (map.containsKey(ClusteringEngine.DEFAULT_ENGINE_NAME)) {
    return;
  }

  // If there's no default algorithm, and there are any algorithms available, 
  // the first definition becomes the default algorithm.
  if (!map.isEmpty()) {
    Entry<String,T> first = map.entrySet().iterator().next();
    map.put(ClusteringEngine.DEFAULT_ENGINE_NAME, first.getValue());
    log.info("Default engine for " + type + ": " + first.getKey());
  }
}
 

import org.apache.solr.handler.clustering.ClusteringEngine; //导入依赖的package包/类
@SuppressWarnings("unchecked")
@Override
public void inform(SolrCore core) {
  if (initParams != null) {
    log.info("Initializing Clustering Engines");

    // Our target list of engines, split into search-results and document clustering.
    SolrResourceLoader loader = core.getResourceLoader();

    for (Map.Entry<String,Object> entry : initParams) {
      if ("engine".equals(entry.getKey())) {
        NamedList<Object> engineInitParams = (NamedList<Object>) entry.getValue();
        
        String engineClassName = StringUtils.defaultIfBlank( 
            (String) engineInitParams.get("classname"),
            CarrotClusteringEngine.class.getName()); 

        // Instantiate the clustering engine and split to appropriate map. 
        final ClusteringEngine engine = loader.newInstance(engineClassName, ClusteringEngine.class);
        final String name = StringUtils.defaultIfBlank(engine.init(engineInitParams, core), "");
        final ClusteringEngine previousEntry;
        if (engine instanceof SearchClusteringEngine) {
          previousEntry = searchClusteringEngines.put(name, (SearchClusteringEngine) engine);
        } else if (engine instanceof DocumentClusteringEngine) {
          previousEntry = documentClusteringEngines.put(name, (DocumentClusteringEngine) engine);
        } else {
          log.warn("Unknown type of a clustering engine for class: " + engineClassName);
          continue;
        }
        if (previousEntry != null) {
          log.warn("Duplicate clustering engine component named '" + name + "'.");
        }
      }
    }

    // Set up the default engine key for both types of engines.
    setupDefaultEngine("search results clustering", searchClusteringEngines);
    setupDefaultEngine("document clustering", documentClusteringEngines);

    log.info("Finished Initializing Clustering Engines");
  }
}
 

import org.apache.solr.handler.clustering.ClusteringEngine; //导入依赖的package包/类
private String getClusteringEngineName(ResponseBuilder rb){
  return rb.req.getParams().get(ClusteringParams.ENGINE_NAME, ClusteringEngine.DEFAULT_ENGINE_NAME);
}