在Lucene中，关闭一个IndexWriter时抛出AlreadyClosedException异常：
org.apache.lucene.store.AlreadyClosedException: this Directory is closed
at org.apache.lucene.store.BaseDirectory.ensureOpen(BaseDirectory.java:66) ~[lucene-core-4.8.1.jar:4.8.1 1594670 – rmuir – 2014-05-14 19:22:52]
at org.apache.lucene.store.FSDirectory.deleteFile(FSDirectory.java:269) ~[lucene-core-4.8.1.jar:4.8.1 1594670 – rmuir – 2014-05-14 19:22:52]
at org.apache.lucene.index.IndexFileDeleter.deleteFile(IndexFileDeleter.java:595) ~[lucene-core-4.8.1.jar:4.8.1 1594670 – rmuir – 2014-05-14 19:22:52]
at org.apache.lucene.index.IndexFileDeleter.deleteNewFiles(IndexFileDeleter.java:582) ~[lucene-core-4.8.1.jar:4.8.1 1594670 – rmuir – 2014-05-14 19:22:52]
at org.apache.lucene.index.IndexWriter.deleteNewFiles(IndexWriter.java:4693) ~[lucene-core-4.8.1.jar:4.8.1 1594670 – rmuir – 2014-05-14 19:22:52]
at org.apache.lucene.index.DocumentsWriter$DeleteNewFilesEvent.process(DocumentsWriter.java:739) ~[lucene-core-4.8.1.jar:4.8.1 1594670 – rmuir – 2014-05-14 19:22:52]
at org.apache.lucene.index.IndexWriter.processEvents(IndexWriter.java:4746) ~[lucene-core-4.8.1.jar:4.8.1 1594670 – rmuir – 2014-05-14 19:22:52]
at org.apache.lucene.index.IndexWriter.processEvents(IndexWriter.java:4738) ~[lucene-core-4.8.1.jar:4.8.1 1594670 – rmuir – 2014-05-14 19:22:52]
at org.apache.lucene.index.IndexWriter.doFlush(IndexWriter.java:3198) ~[lucene-core-4.8.1.jar:4.8.1 1594670 – rmuir – 2014-05-14 19:22:52]
at org.apache.lucene.index.IndexWriter.flush(IndexWriter.java:3170) ~[lucene-core-4.8.1.jar:4.8.1 1594670 – rmuir – 2014-05-14 19:22:52]
at org.apache.lucene.index.IndexWriter.closeInternal(IndexWriter.java:991) ~[lucene-core-4.8.1.jar:4.8.1 1594670 – rmuir – 2014-05-14 19:22:52]
at org.apache.lucene.index.IndexWriter.close(IndexWriter.java:935) ~[lucene-core-4.8.1.jar:4.8.1 1594670 – rmuir – 2014-05-14 19:22:52]
at org.apache.lucene.index.IndexWriter.close(IndexWriter.java:897) ~[lucene-core-4.8.1.jar:4.8.1 1594670 – rmuir – 2014-05-14 19:22:52]
有人说这是因为index目录下的write.lock没有被删除，其实并不是这样。
真正的原因是，IndexWriter依赖于一个Directory，当Directory关闭的时候，IndexWriter也就随之关闭了。所以正确的关闭顺序是
-
先关闭IndexWriter
-
后关闭Directory