solr dataimport 数据导入源码分析（四）

我们查看DocBuilder类的源码发现，并不是直接持有对SqlEntityProcessor类的引用，而是另外一个包装类EntityProcessorWrapper，EntityProcessorWrapper直接继承自抽象类EntityProcessor，而不是继承自中间的EntityProcessorBase类，简要类图如下


包装类额外添加了缓存处理以及格式转换等功能，然后调用SqlEntityProcessor相应方法进行处理，相当于SqlEntityProcessor的代理类，共同继承自抽象类EntityProcessor（SqlEntityProcessor 是通过EntityProcessorBase 间接继承自EntityProcessor）

EntityProcessorWrapper类的简要代码如下

public class EntityProcessorWrapper extends EntityProcessor {

private static final Logger log = LoggerFactory.getLogger(EntityProcessorWrapper.class);

EntityProcessor delegate;

private DocBuilder docBuilder;

String onError;

Context context;

protected VariableResolverImpl resolver;

String entityName;

protected List<Transformer> transformers;

protected List<Map<String, Object>> rowcache;

public EntityProcessorWrapper(EntityProcessor delegate, DocBuilder docBuilder) {

this.delegate = delegate;

this.docBuilder = docBuilder;

}

@Override

public void init(Context context) {

delegate.init(context);

}

protected Map<String, Object> getFromRowCache() {

if (rowcache.isEmpty()){

return null;

}

return rowcache.remove(0);

}

@Override

public Map<String, Object> nextRow() {

pullRow();

}

protected Map<String,Object> pullRow() {

Map<String,Object> arow = null;

try {

arow = delegate.nextRow();

} catch (Exception e) {

if (ABORT.equals(onError)) {

wrapAndThrow(SEVERE, e);

} else {

// SKIP is not really possible. If this calls the nextRow() again the

// Entityprocessor would be in an inconistent state

log.error("Exception in entity : " + entityName, e);

return null;

}

}

log.debug("arow : {}", arow);

return arow;

}

@Override

public Map<String, Object> nextModifiedRowKey() {

Map<String, Object> row = delegate.nextModifiedRowKey();

row = applyTransformer(row);

rowcache = null;

return row;

}

@Override

public Map<String, Object> nextDeletedRowKey() {

Map<String, Object> row = delegate.nextDeletedRowKey();

row = applyTransformer(row);

rowcache = null;

return row;

}

@Override

public Map<String, Object> nextModifiedParentRowKey() {

return delegate.nextModifiedParentRowKey();

}

@Override

public void destroy() {

delegate.destroy();

}

@Override

public void close() {

delegate.close();

}
}