solr dataimport 数据导入源码分析（三）

在介绍DocBuilder 类之前，我们先来解读数据导入对应实体处理器EntityProcessor，默认的实体处理器为SqlEntityProcessor

EntityProcessor 为抽象类，具体方法由子类实现

 package org.apache.solr.handler.dataimport;

import java.util.Map;

public abstract class EntityProcessor {

public abstract void init(Context context);

 public abstract Map<String, Object> nextRow();

public abstract Map<String, Object> nextModifiedRowKey();

public abstract Map<String, Object> nextDeletedRowKey();

public abstract Map<String, Object> nextModifiedParentRowKey();

public abstract void destroy();

public void postTransform(Map<String, Object> r) {

  }

public void close() {

    //no-op

  }

EntityProcessorBase继承类封装公用逻辑，其中比较重要的是getNext()方法，用于遍历数据迭代器，供子类调用

protected Iterator<Map<String, Object>> rowIterator;

protected DIHCacheSupport cacheSupport = null; 

protected Map<String, Object> getNext() {
    if(cacheSupport==null) {
      try {
        if (rowIterator == null)
          return null;
        if (rowIterator.hasNext())
          return rowIterator.next();
        query = null;
        rowIterator = null;
        return null;
      } catch (Exception e) {
        SolrException.log(log, "getNext() failed for query '" + query + "'", e);
        query = null;
        rowIterator = null;
        wrapAndThrow(DataImportHandlerException.WARN, e);
        return null;
      }
    } else  {
      return cacheSupport.getCacheData(context, query, rowIterator);
    }      
  }

真正的数据处理器为SqlEntityProcessor,简要代码如下

 package org.apache.solr.handler.dataimport;

import java.util.Iterator;

import java.util.Map;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import java.util.regex.Matcher;

import java.util.regex.Pattern;



public class SqlEntityProcessor extends EntityProcessorBase {



protected DataSource<Iterator<Map<String, Object>>> dataSource;



  @Override

  @SuppressWarnings("unchecked")

  public void init(Context context) {

    super.init(context);

    dataSource = context.getDataSource();

  }



  protected void initQuery(String q) {

    try {

      DataImporter.QUERY_COUNT.get().incrementAndGet();

      rowIterator = dataSource.getData(q);

      this.query = q;

    } catch (DataImportHandlerException e) {

      throw e;

    } catch (Exception e) {

      LOG.error( "The query failed '" + q + "'", e);

      throw new DataImportHandlerException(DataImportHandlerException.SEVERE, e);

    }

  }



  @Override

  public Map<String, Object> nextRow() {    

    if (rowIterator == null) {

      String q = getQuery();

      initQuery(context.replaceTokens(q));

    }

    return getNext();

  }



  @Override

  public Map<String, Object> nextModifiedRowKey() {

    if (rowIterator == null) {

      String deltaQuery = context.getEntityAttribute(DELTA_QUERY);

      if (deltaQuery == null)

        return null;

      initQuery(context.replaceTokens(deltaQuery));

    }

    return getNext();

  }



  @Override

  public Map<String, Object> nextDeletedRowKey() {

    if (rowIterator == null) {

      String deletedPkQuery = context.getEntityAttribute(DEL_PK_QUERY);

      if (deletedPkQuery == null)

        return null;

      initQuery(context.replaceTokens(deletedPkQuery));

    }

    return getNext();

  }



  @Override

  public Map<String, Object> nextModifiedParentRowKey() {

    if (rowIterator == null) {

      String parentDeltaQuery = context.getEntityAttribute(PARENT_DELTA_QUERY);

      if (parentDeltaQuery == null)

        return null;

      LOG.info("Running parentDeltaQuery for Entity: "

              + context.getEntityAttribute("name"));

      initQuery(context.replaceTokens(parentDeltaQuery));

    }

    return getNext();

  }

}