這篇文章主要介紹“sharding-jdbc的ANTLR4 SQL用法實(shí)例”，在日常操作中，相信很多人在sharding-jdbc的ANTLR4 SQL用法實(shí)例問(wèn)題上存在疑惑，小編查閱了各式資料，整理出簡(jiǎn)單好用的操作方法，希望對(duì)大家解答”sharding-jdbc的ANTLR4 SQL用法實(shí)例”的疑惑有所幫助！接下來(lái)，請(qǐng)跟著小編一起來(lái)學(xué)習(xí)吧！
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Sharding主要利用ANTLR4來(lái)解析SQL，以MySQL為例，分析源碼前可以先了解以下三點(diǎn)：
antlr4，如何編寫(xiě) .g4 語(yǔ)法文件
mysql 語(yǔ)法可以參考https://dev.mysql.com/doc/refman/8.0/en/sql-syntax-data-manipulation.html
mysql g4文件編寫(xiě)可以參考https://github.com/antlr/grammars-v4/blob/master/mysql
1.解析入口ParsingSQLRouter#parse
重慶分公司
重慶分公司
/**
* 解析sql
*
* @param logicSQL 邏輯sql
* @param useCache 是否緩存解析后的結(jié)果
* @return
*/
@Override
public SQLStatement parse(final String logicSQL, final boolean useCache) {
//解析前鉤子，如:調(diào)用鏈etx
parsingHook.start(logicSQL);
try {
//解析SQL
SQLStatement result = new ShardingSQLParseEntry(databaseType, shardingMetaData.getTable(), parsingResultCache).parse(logicSQL, useCache);
//解析成功后鉤子
parsingHook.finishSuccess(result, shardingMetaData.getTable());
return result;
// CHECKSTYLE:OFF
} catch (final Exception ex) {
// CHECKSTYLE:ON
//解析失敗鉤子
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;
}
/**
* 根據(jù)sql獲取解析引擎封裝對(duì)象
*/
@Override
protected SQLParseEngine getSQLParseEngine(final String sql) {
//參數(shù)1：?jiǎn)卫?，加載statement、提取、過(guò)濾配置文件
//參數(shù)2：數(shù)據(jù)庫(kù)類型
//參數(shù)3：需要解析sql
//參數(shù)4：分片表元數(shù)據(jù)
return new SQLParseEngine(ShardingParseRuleRegistry.getInstance(), databaseType, sql, shardingTableMetaData);
}
}2.ShardingParseRuleRegistry.getInstance()->ParseRuleRegistry#initParseRuleDefinition加載statement、提取、過(guò)濾配置文件
private void initParseRuleDefinition() {
//利用JAXB加載META-INF/parsing-rule-definition/extractor-rule-definition.xml配置文件
ExtractorRuleDefinitionEntity generalExtractorRuleEntity = extractorRuleLoader.load(RuleDefinitionFileConstant.getExtractorRuleDefinitionFile());
//利用JAXB加載下META-INF/parsing-rule-definition/filler-rule-definition.xml配置文件
FillerRuleDefinitionEntity generalFillerRuleEntity = fillerRuleLoader.load(RuleDefinitionFileConstant.getFillerRuleDefinitionFile());
//加對(duì)應(yīng)類型(sharding、masterslave、encrypt)配置文件
//META-INF/parsing-rule-definition/sharding/filler-rule-definition.xml
FillerRuleDefinitionEntity featureGeneralFillerRuleEntity = fillerRuleLoader.load(RuleDefinitionFileConstant.getFillerRuleDefinitionFile(getType()));
//根據(jù)數(shù)據(jù)庫(kù)類型加載對(duì)應(yīng)的配置文件
for (DatabaseType each : SQLParserFactory.getAddOnDatabaseTypes()) {
//META-INF/parsing-rule-definition/sharding.mysql/filler-rule-definition.xml
//databaseType:rules
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
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) {
//將所有提取器封裝到一起
//id:extractor
ExtractorRuleDefinition extractorRuleDefinition = new ExtractorRuleDefinition(
generalExtractorRuleEntity, extractorRuleLoader.load(RuleDefinitionFileConstant.getExtractorRuleDefinitionFile(getType(), databaseType)));
//sql-statement-rule-definition.xml
//Context:SQLStatementRule
//SQLStatementRule封裝statement對(duì)應(yīng)的提取器
return new SQLStatementRuleDefinition(statementRuleLoader.load(RuleDefinitionFileConstant.getSQLStatementRuleDefinitionFile(getType(), databaseType)), extractorRuleDefinition);
} 3.SQLParseEntry#parse，這里抽象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) {
//從緩存中獲取解析后的SQLStatement
Optional 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 getSQLStatementFromCache(final String sql, final boolean useCache) {
return useCache ? Optional.fromNullable(parsingResultCache.getSQLStatement(sql)) : Optional.absent();
}
//根據(jù)子類ShardingSQLParseEntry的getSQLParseEngine獲取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，封裝成對(duì)應(yīng)的segment，如TableSegment、IndexSegment
Collection sqlSegments = extractorEngine.extract(ast);
Map parameterMarkerIndexes = ast.getParameterMarkerIndexes();
//填充SQLStatement
return fillerEngine.fill(sqlSegments, parameterMarkerIndexes.size(), ast.getSqlStatementRule());
} 5.SQLParserEngine#parse，解析SQL，封裝AST(Abstract Syntax Tree 抽象語(yǔ)法樹(shù))
public SQLAST parse() {
//SPI 利用ANTLR4解析獲取SQLParser(MySQLParserEntry)執(zhí)行，獲取解析樹(shù)
ParseTree parseTree = SQLParserFactory.newInstance(databaseType, sql).execute().getChild(0);
if (parseTree instanceof ErrorNode) {
throw new SQLParsingException(String.format("Unsupported SQL of `%s`", sql));
}
//獲取配置文件中的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));
}
//封裝ast(Abstract Syntax Tree 抽象語(yǔ)法樹(shù))
return new SQLAST((ParserRuleContext) parseTree, getParameterMarkerIndexes((ParserRuleContext) parseTree), sqlStatementRule);
}
/**
* 遞歸獲取所有參數(shù)占位符
*
* @param rootNode 根節(jié)點(diǎn)
* @return
*/
private Map getParameterMarkerIndexes(final ParserRuleContext rootNode) {
Collection placeholderNodes = ExtractorUtils.getAllDescendantNodes(rootNode, RuleName.PARAMETER_MARKER);
Map result = new HashMap<>(placeholderNodes.size(), 1);
int index = 0;
for (ParserRuleContext each : placeholderNodes) {
result.put(each, index++);
}
return result;
} 6.使用SQLParserFactory#newInstance創(chuàng)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所有擴(kuò)展
for (SQLParserEntry each : NewInstanceServiceLoader.newServiceInstances(SQLParserEntry.class)) {
//判斷數(shù)據(jù)庫(kù)類型
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) {
//詞法分析器
Lexer lexer = parserEntry.getLexerClass().getConstructor(CharStream.class).newInstance(CharStreams.fromString(sql));
//語(yǔ)法分析器
return parserEntry.getParserClass().getConstructor(TokenStream.class).newInstance(new CommonTokenStream(lexer));
}7.以select為例，分析第四步的SQL解析、提取、填充過(guò)程
利用idea的antlr4插件，使用Sharding的mysql .g4 文件解析SQL；如圖：
參考上圖，使用sharding parse解析模塊提取(extractor) ParserRuleContext對(duì)應(yīng)的參數(shù)封裝成Segment
8.SQLSegmentsExtractorEngine#extract，參考第七部圖，根據(jù)SQLStatementRule->tableReferences, columns, selectItems, where, predicate, groupBy, orderBy, limit, subqueryPredicate對(duì)應(yīng)的提取器，生成對(duì)應(yīng)類型的Segment
public final class SQLSegmentsExtractorEngine {
/**
* Extract SQL segments.
*
* @param ast SQL AST
* @return SQL segments
*/
public Collection extract(final SQLAST ast) {
Collection result = new LinkedList<>();
//遍歷Context對(duì)應(yīng)提取器，封裝成對(duì)應(yīng)對(duì)應(yīng)類型的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 = ?為例
//SelectContext->SQLStatementRule
//SQLStatementRule->tableReferences, columns, selectItems, where, predicate, groupBy, orderBy, limit, subqueryPredicate
//分析九個(gè)提取器
for (SQLSegmentExtractor each : ast.getSqlStatementRule().getExtractors()) {
//分兩種類型
//1.單一樹(shù)，直接提取單一RuleName下的token；參看sql解析后的語(yǔ)法樹(shù)對(duì)比比較清晰
if (each instanceof OptionalSQLSegmentExtractor) {
Optional sqlSegment = ((OptionalSQLSegmentExtractor) each).extract(ast.getParserRuleContext(), ast.getParameterMarkerIndexes());
if (sqlSegment.isPresent()) {
result.add(sqlSegment.get());
}
//2.分叉樹(shù)，需遍歷提取RuleName下的所有Token；參看sql解析后的語(yǔ)法樹(shù)對(duì)比比較清晰
} else if (each instanceof CollectionSQLSegmentExtractor) {
result.addAll(((CollectionSQLSegmentExtractor) each).extract(ast.getParserRuleContext(), ast.getParameterMarkerIndexes()));
}
}
return result;
}
} 9.SQLStatementFillerEngine#fill，封裝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 sqlSegments, final int parameterMarkerCount, final SQLStatementRule rule) {
//如SelectStatement
SQLStatement result = rule.getSqlStatementClass().newInstance();
//邏輯sql
result.setLogicSQL(sql);
//參數(shù)個(gè)數(shù)
result.setParametersCount(parameterMarkerCount);
//segment
result.getSQLSegments().addAll(sqlSegments);
//遍歷填充對(duì)應(yīng)類型的Segment
for (SQLSegment each : sqlSegments) {
//根據(jù)數(shù)據(jù)庫(kù)類型、segment找到對(duì)應(yīng)填充器，來(lái)填充對(duì)應(yīng)的segment
//如：TableSegment->TableFiller
Optional 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、字段約束、修改字段、字段命令，這四種填充器需要設(shè)置分片表元數(shù)據(jù)
//主要通過(guò)分片表元數(shù)據(jù)來(lái)填充對(duì)應(yīng)的SQLStatement
if (filler instanceof ShardingTableMetaDataAware) {
((ShardingTableMetaDataAware) filler).setShardingTableMetaData(shardingTableMetaData);
}
//如:
//利用TableFill來(lái)填充SelectStatement#tables
filler.fill(sqlSegment, sqlStatement);
}
} 以上Sharding的SQL解析大概過(guò)程，解析ParserRuleContext提取封裝對(duì)應(yīng)的Segment，最后封裝SQLStatement，并根據(jù)Segment對(duì)應(yīng)的Filler來(lái)填充SQLStatement；具體如何提取、填充可以查看以下三個(gè)文件
extractor-rule-definition.xml
filler-rule-definition.xml
sql-statement-rule-definition.xml
到此，關(guān)于“sharding-jdbc的ANTLR4 SQL用法實(shí)例”的學(xué)習(xí)就結(jié)束了，希望能夠解決大家的疑惑。理論與實(shí)踐的搭配能更好的幫助大家學(xué)習(xí)，快去試試吧！若想繼續(xù)學(xué)習(xí)更多相關(guān)知識(shí)，請(qǐng)繼續(xù)關(guān)注創(chuàng)新互聯(lián)網(wǎng)站，小編會(huì)繼續(xù)努力為大家?guī)?lái)更多實(shí)用的文章！
