Lucene notes ____ notes for indexreader and indexwriter

Source: Internet
Author: User

In the use of javasne, enabling and disabling indexreader and indexwriter is time-consuming, especially for indexreader operations,

(Indexreader reads the index information on the disk into the memory)

Therefore, we generally create indexreader as a single instance to reduce consumption.

Let's look at the example below:

Private indexreader reader; Public indexsearcher getsearcher (directory) {try {If (reader = NULL) {reader = indexreader. open (directory);} else {indexreader TR = indexreader. openifchanged (Reader); If (TR! = NULL) {reader. close (); reader = TR;} return New indexsearcher (Reader);} catch (corruptindexexception e) {e. printstacktrace ();} catch (ioexception e) {e. printstacktrace ();} return NULL ;}

In this case, we will not close the reader and check whether the reader exists during use. Then we can see another function openifchanged.


If the index is opened and the reader changes, a new reader is returned. Otherwise, null is returned. Therefore, openifchanged is used in the preceding method.

To determine whether it is the original reader.

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