Lucene 1.9 多目录搜索的的一个bug

这个问题解决有一段时间了。刚才在Lucene的群有朋友提问了这个问题。所以方便其他朋友遇到此问题时，好参考下。特贴出来

在需要搜索多个索引目录，多个字段的时候，发现有错误，提示的大概意思是(具体忘记了),关键词已经存在字典中。研究Lucene的源代码发现，是Lucene.net 1.9 rc1的一个bug :
具体代码在Lucene.Net.Search命名空间下的Query类的Combine method :

修改前的代码如下：

public virtual Query Combine(Query[] queries)
{
System.Collections.Hashtable uniques = new System.Collections.Hashtable();
for (int i = 0; i < queries.Length; i++)
{
Query query = queries[i];
BooleanClause[] clauses = null;
// check if we can split the query into clauses
bool splittable = (query is BooleanQuery);
if (splittable)
{
BooleanQuery bq = (BooleanQuery) query;
splittable = bq.IsCoordDisabled();
clauses = bq.GetClauses();
for (int j = 0; splittable && j < clauses.Length; j++)
{
splittable = (clauses[j].GetOccur() == BooleanClause.Occur.SHOULD);
}
}
if (splittable)
{
for (int j = 0; j < clauses.Length; j++)
{
Query tmp = clauses[j].GetQuery();
uniques.Add(tmp, tmp);
}
}
else
{
uniques.Add(query, query);
}
}
// optimization: if we have just one query, just return it
if (uniques.Count == 1)
{
return (Query) uniques.GetEnumerator().Current;
}
System.Collections.IEnumerator it = uniques.GetEnumerator();
BooleanQuery result = new BooleanQuery(true);
while (it.MoveNext())
{
result.Add((Query) it.Current, BooleanClause.Occur.SHOULD);
}
return result;
}

修改后的代码(飘红的地方是更改过的)：

public virtual Query Combine(Query[] queries)
{
System.Collections.Hashtable uniques = new System.Collections.Hashtable();
for (int i = 0; i < queries.Length; i++)
{
Query query = queries[i];
BooleanClause[] clauses = null;
// check if we can split the query into clauses
bool splittable = (query is BooleanQuery);
if (splittable)
{
BooleanQuery bq = (BooleanQuery) query;
splittable = bq.IsCoordDisabled();
clauses = bq.GetClauses();
for (int j = 0; splittable && j < clauses.Length; j++)
{
splittable = (clauses[j].GetOccur() == BooleanClause.Occur.SHOULD);
}
}
if (splittable)
{
for (int j = 0; j < clauses.Length; j++)
{
Query tmp = clauses[j].GetQuery();
uniques.Add(tmp, tmp);
}
}
else
{
//uniques.Add(query, query);

//modify by kwklover 2008/1/17 bug fixed for 防止加入多个重复的字典项
if (uniques.Contains(query) == false)
{
uniques.Add(query, query);
}
}
}
// optimization: if we have just one query, just return it
if (uniques.Count == 1)
{
//return (Query) uniques.GetEnumerator().Current;

//modify by kwklover 2008/1/17
System.Collections.IDictionaryEnumerator iter = uniques.GetEnumerator();
iter.MoveNext();
return iter.Value as Query;
}
System.Collections.IEnumerator it = uniques.GetEnumerator();
BooleanQuery result = new BooleanQuery(true);
while (it.MoveNext())
{
result.Add((Query) it.Current, BooleanClause.Occur.SHOULD);
}
return result;
}

另外在Lucene 2.0版已经修复了此问题。不过Lucene 2.0 和 Lucene 1.9的 API有比较大的变化