fix: 修复 Lucene 特殊字符查询失败

- 将用户关键词按普通文本转义后再解析

- 避免空查询和解析失败触发二次空指针

- 补充特殊字符与空查询回归测试

easy-agents-search-engine/easy-agents-search-engine-lucene/src/main/java/com/easyagents/search/engine/lucene/LuceneSearcher.java

@@ -199,10 +199,13 @@ public class LuceneSearcher implements DocumentSearcher, AutoCloseable {
     @Override
     public List<Document> searchDocuments(KeywordSearchRequest request) {
         List<Document> results = new ArrayList<>();
+        if (request == null || request.getKeyword() == null || request.getKeyword().trim().isEmpty()) {
+            return results;
+        }
         try (IndexReader reader = DirectoryReader.open(directory)) {
             IndexSearcher searcher = new IndexSearcher(reader);
             Query query = buildQuery(request);
-            TopDocs topDocs = searcher.search(query, request == null ? 10 : request.getCount());
+            TopDocs topDocs = searcher.search(query, request.getCount());
             for (ScoreDoc scoreDoc : topDocs.scoreDocs) {
                 org.apache.lucene.document.Document doc = searcher.doc(scoreDoc.doc);
                 Document resultDoc = new Document();
@@ -224,29 +227,24 @@ public class LuceneSearcher implements DocumentSearcher, AutoCloseable {
         return results;
     }
 
-    Query buildQuery(KeywordSearchRequest request) {
-        try {
-            String keyword = request == null ? null : request.getKeyword();
+    Query buildQuery(KeywordSearchRequest request) throws ParseException {
+        String escapedKeyword = QueryParser.escape(request.getKeyword());
 
         QueryParser titleQueryParser = new QueryParser("title", analyzer);
-            Query titleQuery = titleQueryParser.parse(keyword);
+        Query titleQuery = titleQueryParser.parse(escapedKeyword);
         BooleanClause titleBooleanClause = new BooleanClause(titleQuery, BooleanClause.Occur.SHOULD);
 
         QueryParser contentQueryParser = new QueryParser("content", analyzer);
-            Query contentQuery = contentQueryParser.parse(keyword);
+        Query contentQuery = contentQueryParser.parse(escapedKeyword);
         BooleanClause contentBooleanClause = new BooleanClause(contentQuery, BooleanClause.Occur.SHOULD);
 
         BooleanQuery.Builder builder = new BooleanQuery.Builder();
         builder.add(titleBooleanClause)
             .add(contentBooleanClause);
-            if (request != null && request.getKnowledgeId() != null && !request.getKnowledgeId().trim().isEmpty()) {
+        if (request.getKnowledgeId() != null && !request.getKnowledgeId().trim().isEmpty()) {
             builder.add(new TermQuery(new Term(KeywordSearchMetadataKeys.KNOWLEDGE_ID, request.getKnowledgeId().trim())), BooleanClause.Occur.MUST);
         }
         return builder.build();
-        } catch (ParseException e) {
-            LOG.error(e.toString(), e);
-        }
-        return null;
     }
 
     private static Analyzer createAnalyzer() {

easy-agents-search-engine/easy-agents-search-engine-lucene/src/test/java/com/easyagents/search/engine/lucene/LuceneSearcherTest.java

@@ -57,6 +57,45 @@ public class LuceneSearcherTest {
         }
     }
 
+    /**
+     * 验证用户输入中的 Lucene 特殊字符按普通文本检索。
+     *
+     * @throws Exception 临时目录或 Lucene 资源操作失败时抛出
+     */
+    @Test
+    public void shouldTreatLuceneSpecialCharactersAsPlainText() throws Exception {
+        Path tempDir = Files.createTempDirectory("lucene-searcher-special-character-test");
+        LuceneConfig config = new LuceneConfig();
+        config.setIndexDirPath(tempDir.toString());
+        try (LuceneSearcher searcher = new LuceneSearcher(config)) {
+            Document document = new Document();
+            document.setId("special-character");
+            document.setContent("A/C.\\nPLEASE");
+            Assert.assertTrue(searcher.addDocument(document));
+
+            List<Document> results = searcher.searchDocuments("A/C.\\nPLEASE", 10);
+
+            Assert.assertEquals(1, results.size());
+            Assert.assertEquals("special-character", String.valueOf(results.get(0).getId()));
+        }
+    }
+
+    /**
+     * 验证空查询直接返回空结果。
+     *
+     * @throws Exception 临时目录或 Lucene 资源操作失败时抛出
+     */
+    @Test
+    public void shouldReturnEmptyForMissingKeyword() throws Exception {
+        Path tempDir = Files.createTempDirectory("lucene-searcher-empty-keyword-test");
+        LuceneConfig config = new LuceneConfig();
+        config.setIndexDirPath(tempDir.toString());
+        try (LuceneSearcher searcher = new LuceneSearcher(config)) {
+            Assert.assertTrue(searcher.searchDocuments((KeywordSearchRequest) null).isEmpty());
+            Assert.assertTrue(searcher.searchDocuments("   ", 10).isEmpty());
+        }
+    }
+
     /**
      * 验证多个导入线程可共享同一个 IndexWriter 完成批量写入。
      *