public static ProxyBackendHandler newInstance()

in proxy/backend/core/src/main/java/org/apache/shardingsphere/proxy/backend/handler/ProxyBackendHandlerFactory.java [109:150]
42 lines of code
10 McCabe index (conditional complexity)

    public static ProxyBackendHandler newInstance(final DatabaseType databaseType, final QueryContext queryContext,
                                                  final ConnectionSession connectionSession, final boolean preferPreparedStatement) throws SQLException {
        SQLStatementContext sqlStatementContext = queryContext.getSqlStatementContext();
        SQLStatement sqlStatement = sqlStatementContext.getSqlStatement();
        allowExecutingWhenTransactionalError(databaseType, connectionSession, sqlStatement);
        checkUnsupportedSQLStatement(sqlStatement);
        checkClusterState(sqlStatement);
        if (sqlStatement instanceof EmptyStatement) {
            return new SkipBackendHandler(sqlStatement);
        }
        if (sqlStatement instanceof DistSQLStatement) {
            checkUnsupportedDistSQLStatementInTransaction(sqlStatement, connectionSession);
            return DistSQLBackendHandlerFactory.newInstance((DistSQLStatement) sqlStatement, connectionSession);
        }
        String sql = queryContext.getSql();
        handleAutoCommit(sqlStatement, connectionSession);
        if (sqlStatement instanceof TCLStatement) {
            return TCLBackendHandlerFactory.newInstance(sqlStatementContext, sql, connectionSession);
        }
        Optional<ProxyBackendHandler> backendHandler = DatabaseAdminBackendHandlerFactory.newInstance(databaseType, sqlStatementContext, connectionSession, sql, queryContext.getParameters());
        if (backendHandler.isPresent()) {
            return backendHandler.get();
        }
        Optional<ProxyBackendHandler> databaseOperateHandler = findDatabaseOperateBackendHandler(sqlStatement, connectionSession);
        if (databaseOperateHandler.isPresent()) {
            return databaseOperateHandler.get();
        }
        String databaseName = sqlStatementContext instanceof TableAvailable && ((TableAvailable) sqlStatementContext).getTablesContext().getDatabaseName().isPresent()
                ? ((TableAvailable) sqlStatementContext).getTablesContext().getDatabaseName().get()
                : connectionSession.getUsedDatabaseName();
        if (null == databaseName) {
            return DatabaseBackendHandlerFactory.newInstance(queryContext, connectionSession, preferPreparedStatement);
        }
        Grantee grantee = connectionSession.getConnectionContext().getGrantee();
        ShardingSphereMetaData metaData = ProxyContext.getInstance().getContextManager().getMetaDataContexts().getMetaData();
        ShardingSphereDatabase database = metaData.getDatabase(databaseName);
        for (SQLExecutionChecker each : ShardingSphereServiceLoader.getServiceInstances(SQLExecutionChecker.class)) {
            each.check(metaData, grantee, queryContext, database);
        }
        return DatabaseAdminBackendHandlerFactory.newInstance(databaseType, sqlStatementContext, connectionSession)
                .orElseGet(() -> DatabaseBackendHandlerFactory.newInstance(queryContext, connectionSession, preferPreparedStatement));
    }