这篇文章主要介绍“sharding-jdbc的ANTLR4 SQL用法实例”,在日常操作中,相信很多人在sharding-jdbc的ANTLR4 SQL用法实例问题上存在疑惑,小编查阅了各式资料,整理出简单好用的操作方法,希望对大家解答”sharding-jdbc的ANTLR4 SQL用法实例”的疑惑有所帮助!接下来,请跟着小编一起来学习吧!
Sharding主要利用ANTLR4来解析SQL,以mysql为例,分析源码前可以先了解以下三点:
antlr4,如何编写 .g4
语法文件
mysql 语法可以参考https://dev.mysql.com/doc/refman/8.0/en/sql-syntax-data-manipulation.html
mysql g4文件编写可以参考https://github.com/antlr/grammars-v4/blob/master/mysql
1.解析入口ParsingSQLRouter#parse
/** * 解析sql * * @param logicSQL 逻辑sql * @param useCache 是否缓存解析后的结果 * @return */ @Override public SQLStatement parse(final String logicSQL, final boolean useCache) { //解析前钩子,如:调用链etx parsingHook.start(logicSQL); try { //解析SQL SQLStatement result = new ShardingSQLParseEntry(databaseType, shardingMetaData.getTable(), parsingResultCache).parse(logicSQL, useCache); //解析成功后钩子 parsingHook.finishSuccess(result, shardingMetaData.getTable()); return result; // CHECKSTYLE:OFF } catch (final Exception ex) { // CHECKSTYLE:ON //解析失败钩子 parsingHook.finishFailure(ex); throw ex; } }
public final class ShardingSQLParseEntry extends SQLParseEntry { private final DatabaseType databaseType; private final ShardingTableMetaData shardingTableMetaData; public ShardingSQLParseEntry(final DatabaseType databaseType, final ShardingTableMetaData shardingTableMetaData, final ParsingResultCache parsingResultCache) { super(parsingResultCache); this.databaseType = databaseType; this.shardingTableMetaData = shardingTableMetaData; } /** * 根据sql获取解析引擎封装对象 */ @Override protected SQLParseEngine getSQLParseEngine(final String sql) { //参数1:单例,加载statement、提取、过滤配置文件 //参数2:数据库类型 //参数3:需要解析sql //参数4:分片表元数据 return new SQLParseEngine(ShardingParseRuleRegistry.getInstance(), databaseType, sql, shardingTableMetaData); } }
2.ShardingParseRuleRegistry.getInstance()->ParseRuleRegistry#initParseRuleDefinition加载statement、提取、过滤配置文件
private void initParseRuleDefinition() { //利用JAXB加载META-INF/parsing-rule-definition/extractor-rule-definition.xml配置文件 ExtractorRuleDefinitionEntity generalExtractorRuleEntity = extractorRuleLoader.load(RuleDefinitionFileConstant.getExtractorRuleDefinitionFile()); //利用JAXB加载下META-INF/parsing-rule-definition/filler-rule-definition.xml配置文件 FillerRuleDefinitionEntity generalFillerRuleEntity = fillerRuleLoader.load(RuleDefinitionFileConstant.getFillerRuleDefinitionFile()); //加对应类型(sharding、masterslave、encrypt)配置文件 //META-INF/parsing-rule-definition/sharding/filler-rule-definition.xml FillerRuleDefinitionEntity featureGeneralFillerRuleEntity = fillerRuleLoader.load(RuleDefinitionFileConstant.getFillerRuleDefinitionFile(getType())); //根据数据库类型加载对应的配置文件 for (DatabaseType each : SQLParserFactory.getAddOnDatabaseTypes()) { //META-INF/parsing-rule-definition/sharding.mysql/filler-rule-definition.xml //databaseType:rules<segment,filler> fillerRuleDefinitions.put(each, createFillerRuleDefinition(generalFillerRuleEntity, featureGeneralFillerRuleEntity, each)); //META-INF/parsing-rule-definition/sharding.mysql/extractor-rule-definition.xml //META-INF/parsing-rule-definition/sharding.mysql/sql-statement-rule-definition.xml //databaseType:rules<xxxContext,SQLStatementRule> sqlStatementRuleDefinitions.put(each, createSQLStatementRuleDefinition(generalExtractorRuleEntity, each)); } } private FillerRuleDefinition createFillerRuleDefinition(final FillerRuleDefinitionEntity generalFillerRuleEntity, final FillerRuleDefinitionEntity featureGeneralFillerRuleEntity, final DatabaseType databaseType) { return new FillerRuleDefinition( generalFillerRuleEntity, featureGeneralFillerRuleEntity, fillerRuleLoader.load(RuleDefinitionFileConstant.getFillerRuleDefinitionFile(getType(), databaseType))); } private SQLStatementRuleDefinition createSQLStatementRuleDefinition(final ExtractorRuleDefinitionEntity generalExtractorRuleEntity, final DatabaseType databaseType) { //将所有提取器封装到一起 //id:extractor ExtractorRuleDefinition extractorRuleDefinition = new ExtractorRuleDefinition( generalExtractorRuleEntity, extractorRuleLoader.load(RuleDefinitionFileConstant.getExtractorRuleDefinitionFile(getType(), databaseType))); //sql-statement-rule-definition.xml //Context:SQLStatementRule //SQLStatementRule封装statement对应的提取器 return new SQLStatementRuleDefinition(statementRuleLoader.load(RuleDefinitionFileConstant.getSQLStatementRuleDefinitionFile(getType(), databaseType)), extractorRuleDefinition); }
3.SQLParseEntry#parse,这里抽象SQLParseEntry,主要有不同入口(EncryptSQLParseEntry、MasterSlaveSQLParseEntry、ShardingSQLParseEntry)
@RequiredArgsConstructor public abstract class SQLParseEntry { private final ParsingResultCache parsingResultCache; /** * Parse SQL. * * @param sql SQL * @param useCache use cache or not * @return SQL statement */ public final SQLStatement parse(final String sql, final boolean useCache) { //从缓存中获取解析后的SQLStatement Optional<SQLStatement> cachedSQLStatement = getSQLStatementFromCache(sql, useCache); if (cachedSQLStatement.isPresent()) { return cachedSQLStatement.get(); } //解析 SQLStatement result = getSQLParseEngine(sql).parse(); //cache if (useCache) { parsingResultCache.put(sql, result); } return result; } private Optional<SQLStatement> getSQLStatementFromCache(final String sql, final boolean useCache) { return useCache ? Optional.fromNullable(parsingResultCache.getSQLStatement(sql)) : Optional.<SQLStatement>absent(); } //根据子类ShardingSQLParseEntry的getSQLParseEngine获取SQLParseEngine protected abstract SQLParseEngine getSQLParseEngine(String sql); }
4.SQLParseEngine#parse,包含解析、提取、填充SQLStatement
public SQLParseEngine(final ParseRuleRegistry parseRuleRegistry, final DatabaseType databaseType, final String sql, final ShardingTableMetaData shardingTableMetaData) { DatabaseType trunkDatabaseType = DatabaseTypes.getTrunkDatabaseType(databaseType.getName()); //sql解析引擎 parserEngine = new SQLParserEngine(parseRuleRegistry, trunkDatabaseType, sql); //sql提取引擎 extractorEngine = new SQLSegmentsExtractorEngine(); //sql填充引擎 fillerEngine = new SQLStatementFillerEngine(parseRuleRegistry, trunkDatabaseType, sql, shardingTableMetaData); } /** * Parse SQL. * * @return SQL statement */ public SQLStatement parse() { //利用ANTLR4 解析sql SQLAST ast = parserEngine.parse(); //提取ast中的token,封装成对应的segment,如TableSegment、IndexSegment Collection<SQLSegment> sqlSegments = extractorEngine.extract(ast); Map<ParserRuleContext, Integer> parameterMarkerIndexes = ast.getParameterMarkerIndexes(); //填充SQLStatement return fillerEngine.fill(sqlSegments, parameterMarkerIndexes.size(), ast.getSqlStatementRule()); }
5.SQLParserEngine#parse,解析SQL,封装AST(Abstract Syntax Tree 抽象语法树)
public SQLAST parse() { //SPI 利用ANTLR4解析获取SQLParser(MySQLParserEntry)执行,获取解析树 ParseTree parseTree = SQLParserFactory.newInstance(databaseType, sql).execute().getChild(0); if (parseTree instanceof ErrorNode) { throw new SQLParsingException(String.format("Unsupported SQL of `%s`", sql)); } //获取配置文件中的StatementContext,比如CreateTableContext、SelectContext SQLStatementRule sqlStatementRule = parseRuleRegistry.getSQLStatementRule(databaseType, parseTree.getClass().getSimpleName()); if (null == sqlStatementRule) { throw new SQLParsingException(String.format("Unsupported SQL of `%s`", sql)); } //封装ast(Abstract Syntax Tree 抽象语法树) return new SQLAST((ParserRuleContext) parseTree, getParameterMarkerIndexes((ParserRuleContext) parseTree), sqlStatementRule); } /** * 递归获取所有参数占位符 * * @param rootNode 根节点 * @return */ private Map<ParserRuleContext, Integer> getParameterMarkerIndexes(final ParserRuleContext rootNode) { Collection<ParserRuleContext> placeholderNodes = ExtractorUtils.getAllDescendantNodes(rootNode, RuleName.PARAMETER_MARKER); Map<ParserRuleContext, Integer> result = new HashMap<>(placeholderNodes.size(), 1); int index = 0; for (ParserRuleContext each : placeholderNodes) { result.put(each, index++); } return result; }
6.使用SQLParserFactory#newInstance创建SQLParser
/** * New instance of SQL parser. * * @param databaseType database type * @param sql SQL * @return SQL parser */ public static SQLParser newInstance(final DatabaseType databaseType, final String sql) { //SPI load所有扩展 for (SQLParserEntry each : NewInstanceServiceLoader.newServiceInstances(SQLParserEntry.class)) { //判断数据库类型 if (DatabaseTypes.getActualDatabaseType(each.getDatabaseType()) == databaseType) { //解析sql return createSQLParser(sql, each); } } throw new UnsupportedOperationException(String.format("Cannot support database type '%s'", databaseType)); } @SneakyThrows private static SQLParser createSQLParser(final String sql, final SQLParserEntry parserEntry) { //词法分析器 Lexer lexer = parserEntry.getLexerClass().getConstructor(CharStream.class).newInstance(CharStreams.fromString(sql)); //语法分析器 return parserEntry.getParserClass().getConstructor(TokenStream.class).newInstance(new CommonTokenStream(lexer)); }
7.以select为例,分析第四步的SQL解析、提取、填充过程
利用idea的antlr4插件,使用Sharding的mysql .g4
文件解析SQL;如图:
参考上图,使用sharding parse解析模块提取(extractor) ParserRuleContext对应的参数封装成Segment
8.SQLSegmentsExtractorEngine#extract,参考第七部图,根据SQLStatementRule->tableReferences, columns, selectItems, where, predicate, groupBy, orderBy, limit, subqueryPredicate对应的提取器,生成对应类型的Segment
public final class SQLSegmentsExtractorEngine { /** * Extract SQL segments. * * @param ast SQL AST * @return SQL segments */ public Collection<SQLSegment> extract(final SQLAST ast) { Collection<SQLSegment> result = new LinkedList<>(); //遍历Context对应提取器,封装成对应对应类型的Segment,比如TableSegment、IndexSegment //以SELECT i.* FROM t_order o, t_order_item i WHERE o.order_id = i.order_id and o.order_id = ?为例 //SelectContext->SQLStatementRule //SQLStatementRule->tableReferences, columns, selectItems, where, predicate, groupBy, orderBy, limit, subqueryPredicate //分析九个提取器 for (SQLSegmentExtractor each : ast.getSqlStatementRule().getExtractors()) { //分两种类型 //1.单一树,直接提取单一RuleName下的token;参看sql解析后的语法树对比比较清晰 if (each instanceof OptionalSQLSegmentExtractor) { Optional<? extends SQLSegment> sqlSegment = ((OptionalSQLSegmentExtractor) each).extract(ast.getParserRuleContext(), ast.getParameterMarkerIndexes()); if (sqlSegment.isPresent()) { result.add(sqlSegment.get()); } //2.分叉树,需遍历提取RuleName下的所有Token;参看sql解析后的语法树对比比较清晰 } else if (each instanceof CollectionSQLSegmentExtractor) { result.addAll(((CollectionSQLSegmentExtractor) each).extract(ast.getParserRuleContext(), ast.getParameterMarkerIndexes())); } } return result; } }
9.SQLStatementFillerEngine#fill,封装SQLStatement,填充Segment
@RequiredArgsConstructor public final class SQLStatementFillerEngine { private final ParseRuleRegistry parseRuleRegistry; private final DatabaseType databaseType; private final String sql; private final ShardingTableMetaData shardingTableMetaData; /** * Fill SQL statement. * * @param sqlSegments SQL segments * @param parameterMarkerCount parameter marker count * @param rule SQL statement rule * @return SQL statement */ @SneakyThrows public SQLStatement fill(final Collection<SQLSegment> sqlSegments, final int parameterMarkerCount, final SQLStatementRule rule) { //如SelectStatement SQLStatement result = rule.getSqlStatementClass().newInstance(); //逻辑sql result.setLogicSQL(sql); //参数个数 result.setParametersCount(parameterMarkerCount); //segment result.getSQLSegments().addAll(sqlSegments); //遍历填充对应类型的Segment for (SQLSegment each : sqlSegments) { //根据数据库类型、segment找到对应填充器,来填充对应的segment //如:TableSegment->TableFiller Optional<SQLSegmentFiller> filler = parseRuleRegistry.findSQLSegmentFiller(databaseType, each.getClass()); if (filler.isPresent()) { doFill(each, result, filler.get()); } } return result; } @SuppressWarnings("unchecked") private void doFill(final SQLSegment sqlSegment, final SQLStatement sqlStatement, final SQLSegmentFiller filler) { //添加字段、字段约束、修改字段、字段命令,这四种填充器需要设置分片表元数据 //主要通过分片表元数据来填充对应的SQLStatement if (filler instanceof ShardingTableMetaDataAware) { ((ShardingTableMetaDataAware) filler).setShardingTableMetaData(shardingTableMetaData); } //如: //利用TableFill来填充SelectStatement#tables filler.fill(sqlSegment, sqlStatement); } }
以上Sharding的SQL解析大概过程,解析ParserRuleContext提取封装对应的Segment,最后封装SQLStatement,并根据Segment对应的Filler来填充SQLStatement;具体如何提取、填充可以查看以下三个文件
extractor-rule-definition.xml
filler-rule-definition.xml
sql-statement-rule-definition.xml
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