使用Lucene 10.0.0读取老旧Apache Lucene索引失败求助

问题背景 #

作为Lucene和Java新手，尝试读取一个8-10年历史的旧索引，使用Lucene 10.0.0和JDK 23.0时触发版本兼容错误，尝试过Lucene 3.0.3等版本仍无法读取，仅需提取索引数据后用最新版本重建索引。

系统环境 #

• Windows 10
• Lucene 10.0.0
• JDK 23.0

索引目录文件 #

测试代码 #

import java.util.List;
import java.io.IOException;
import java.nio.file.Paths;

import org.apache.lucene.document.Document;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.StoredFields;
import org.apache.lucene.index.IndexableField;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.search.MatchAllDocsQuery;

public class FieldReader {

    private static final String INDEX_PATH = "indexedfiles";

    public static void main(String[] args) throws Exception {
        IndexReader reader = DirectoryReader.open(FSDirectory.open(Paths.get(INDEX_PATH)));
        //Index searcher
        IndexSearcher searcher = new IndexSearcher(reader);
        //This query will match with all documents in the index
        Query query = new MatchAllDocsQuery();
        //search the index
        TopDocs foundDocs = searcher.search(query, 10);
        // Returns a StoredFields reader for the stored fields of this index. 
        StoredFields storedFields = searcher.storedFields();

        //Let's print out the path of document files and fields
        for (ScoreDoc sd : foundDocs.scoreDocs) {
          Document doc = storedFields.document(sd.doc);
          System.out.println("Path : " + doc.get("path"));
          List<IndexableField> fields = doc.getFields();
            for (IndexableField field : fields) {
                System.out.println("Name : " + field.name() + ", Type : " + field.fieldType().toString());
            }
        }
    }
}

报错信息 #

Exception in thread "main" org.apache.lucene.index.IndexFormatTooOldException:
Format version is not supported
(resource BufferedChecksumIndexInput(MemorySegmentIndexInput(path="D:\IndiaLawLibrary\AHC\s_index\a\segments_2"))): -9 (needs to be between 1071082519 and 1071082519).
This version of Lucene only supports indexes created with release 9.0 and later.

解决步骤 #

1. 定位索引对应的Lucene版本 #

报错中的版本号-9对应Lucene 3.1.x版本（早期Lucene用负数标识segments格式版本，-9是3.1的专属版本号），3.0.3与3.1索引格式不兼容，必须使用Lucene 3.1.0或3.1.1读取。

2. 搭建兼容运行环境 #

• JDK版本：Lucene 3.1.x最高适配JDK 1.7，建议使用JDK 1.7（避免高版本JDK的语法或API兼容问题）。
• 依赖准备：下载Lucene 3.1.1核心jar包（lucene-core-3.1.1.jar），读取存储字段无需额外依赖。

3. 适配Lucene 3.1 API编写读取代码 #

Lucene 3.x与10.x API差异较大，修改后的读取代码如下：

import java.io.File;
import java.util.List;

import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.MatchAllDocsQuery;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.store.FSDirectory;

public class OldIndexReader {
    private static final String OLD_INDEX_PATH = "D:\\IndiaLawLibrary\\AHC\\s_index\\a";

    public static void main(String[] args) throws Exception {
        // 打开旧索引
        IndexReader reader = IndexReader.open(FSDirectory.open(new File(OLD_INDEX_PATH)));
        IndexSearcher searcher = new IndexSearcher(reader);
        
        // 查询所有文档
        MatchAllDocsQuery query = new MatchAllDocsQuery();
        TopDocs topDocs = searcher.search(query, reader.maxDoc());
        
        // 遍历提取存储字段数据
        for (ScoreDoc sd : topDocs.scoreDocs) {
            Document doc = reader.document(sd.doc);
            System.out.println("Path : " + doc.get("path"));
            List<Field> fields = doc.getFields();
            for (Field field : fields) {
                System.out.println("Name : " + field.name() + ", Type : " + field.fieldType());
            }
        }
        
        reader.close();
    }
}

4. 迁移数据到新索引 #

• 运行上述代码提取所有文档的存储字段后，使用Lucene 10.x的API创建新索引，将提取的数据写入。
• 注意字段类型映射：旧版本的Field.Store.YES对应新版本的StoredField或StringField（根据是否需要索引调整）。

依赖获取 #

若使用Maven，可添加以下依赖坐标下载Lucene 3.1.1：

<dependency>
    <groupId>org.apache.lucene</groupId>
    <artifactId>lucene-core</artifactId>
    <version>3.1.1</version>
</dependency>

内容的提问来源于stack exchange，提问作者Prashant