Kylin 概述

Apache Kylin™是一个开源的分布式分析引擎，提供Hadoop/Spark之上的SQL查询接口及多维分析（OLAP）能力以支持超大规模数据，最初由eBay Inc. 开发并贡献至开源社区。它能在亚秒内查询巨大的Hive表。

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Kylin 特性

image.png

JDBC

认证

基于Apache Kylin认证RESTFUL服务。支持的参数：

user : 用户名
password : 密码
ssl: true或false。 默认为flas；如果为true，所有的服务调用都会使用https。

连接url格式：

jdbc:kylin://<hostname>:<port>/<kylin_project_name>

如果“ssl”为true，“port”应该是Kylin server的HTTPS端口。
如果“port”未被指定，driver会使用默认的端口：HTTP 80，HTTPS 443。
必须指定“kylin_project_name”并且用户需要确保它在Kylin server上存在。

1. 使用Statement查询

Driver driver = (Driver) Class.forName("org.apache.kylin.jdbc.Driver").newInstance();

Properties info = new Properties();
info.put("user", "ADMIN");
info.put("password", "KYLIN");
Connection conn = driver.connect("jdbc:kylin://localhost:7070/kylin_project_name", info);
Statement state = conn.createStatement();
ResultSet resultSet = state.executeQuery("select * from test_table");

while (resultSet.next()) {
    assertEquals("foo", resultSet.getString(1));
    assertEquals("bar", resultSet.getString(2));
    assertEquals("tool", resultSet.getString(3));
}

2. 使用PreparedStatementv查询

支持的PreparedStatement参数：
setString
setInt
setShort
setLong
setFloat
setDouble
setBoolean
setByte
setDate
setTime
setTimestamp

Driver driver = (Driver) Class.forName("org.apache.kylin.jdbc.Driver").newInstance();
Properties info = new Properties();
info.put("user", "ADMIN");
info.put("password", "KYLIN");
Connection conn = driver.connect("jdbc:kylin://localhost:7070/kylin_project_name", info);
PreparedStatement state = conn.prepareStatement("select * from test_table where id=?");
state.setInt(1, 10);
ResultSet resultSet = state.executeQuery();

while (resultSet.next()) {
    assertEquals("foo", resultSet.getString(1));
    assertEquals("bar", resultSet.getString(2));
    assertEquals("tool", resultSet.getString(3));
}

3. 获取查询结果元数据

Kylin jdbc driver支持元数据列表方法：
通过sql模式过滤器（比如 %）列出catalog、schema、table和column。

Driver driver = (Driver) Class.forName("org.apache.kylin.jdbc.Driver").newInstance();
Properties info = new Properties();
info.put("user", "ADMIN");
info.put("password", "KYLIN");
Connection conn = driver.connect("jdbc:kylin://localhost:7070/kylin_project_name", info);
Statement state = conn.createStatement();
ResultSet resultSet = state.executeQuery("select * from test_table");

ResultSet tables = conn.getMetaData().getTables(null, null, "dummy", null);
while (tables.next()) {
    for (int i = 0; i < 10; i++) {
        assertEquals("dummy", tables.getString(i + 1));
    }
}

Spring DataSource封装

JDBC方式在开发使用中十分不便，而如果能封装为Spring 提供的DataSource方式，使用过程中就会便捷很多。

创建SqlProperties，封装jdbc连接的参数

@Data
public class KylinSqlProperties {

    private static final String DEFAULT_DRIVER_CLASS_NAME = "org.apache.kylin.jdbc.Driver";
    private static final int DEFAULT_POOL_SIZE = 10;
    private static final Long DEFAULT_MAX_WAIT_TIME = 10000L;

    /**
     * 用户名
     */
    private String userName;

    /**
     * 密码
     */
    private String password;

    /**
     * 是否加密
     */
    private boolean decrypt;

    /**
     * 主库连接地址
     */
    private String connectionUrl;


    /**
     * 最长等待连接时间
     */
    private long maxWaitTime = DEFAULT_MAX_WAIT_TIME;

    private int poolSize = DEFAULT_POOL_SIZE;

    private String driverClassName = DEFAULT_DRIVER_CLASS_NAME;
}

实现 DataSource 接口，创建连接池

@Slf4j
public class KylinDataSource implements DataSource {

    private LinkedList<Connection> connectionPoolList = new LinkedList<>();
    private long maxWaitTime;

    public KylinDataSource(KylinSqlProperties sqlProperties) {
        try {
            this.maxWaitTime = sqlProperties.getMaxWaitTime();
            Driver driverManager = (Driver) Class.forName(sqlProperties.getDriverClassName())
                    .newInstance();
            Properties info = new Properties();
            info.put("user", sqlProperties.getUserName());
            info.put("password", sqlProperties.getPassword());
            for (int i = 0; i < sqlProperties.getPoolSize(); i++) {
                Connection connection = driverManager
                        .connect(sqlProperties.getConnectionUrl(), info);
                connectionPoolList.add(ConnectionProxy.getProxy(connection, connectionPoolList));
            }
            log.info("PrestoDataSource has initialized {} size connection pool",
                    connectionPoolList.size());
        } catch (Exception e) {
            log.error("kylinDataSource initialize error, ex: ", e);
        }
    }

    @Override
    public Connection getConnection() throws SQLException {
        synchronized (connectionPoolList) {
            if (connectionPoolList.size() <= 0) {
                try {
                    connectionPoolList.wait(maxWaitTime);
                } catch (InterruptedException e) {
                    throw new SQLException("getConnection timeout..." + e.getMessage());
                }
            }

            return connectionPoolList.removeFirst();
        }
    }


    @Override
    public Connection getConnection(String username, String password) throws SQLException {
        return getConnection();
    }

    @Override
    public <T> T unwrap(Class<T> iface) throws SQLException {
        throw new RuntimeException("Unsupport operation.");
    }

    @Override
    public boolean isWrapperFor(Class<?> iface) throws SQLException {
        return DataSource.class.equals(iface);
    }

    @Override
    public PrintWriter getLogWriter() throws SQLException {
        throw new RuntimeException("Unsupport operation.");
    }

    @Override
    public void setLogWriter(PrintWriter out) throws SQLException {

    }

    @Override
    public void setLoginTimeout(int seconds) throws SQLException {
        throw new RuntimeException("Unsupport operation.");
    }

    @Override
    public int getLoginTimeout() throws SQLException {
        return 0;
    }

    @Override
    public Logger getParentLogger() throws SQLFeatureNotSupportedException {
        return null;
    }


    static class ConnectionProxy implements InvocationHandler {

        private Object obj;
        private LinkedList<Connection> pool;
        private String DEFAULT_CLOSE_METHOD = "close";

        private ConnectionProxy(Object obj, LinkedList<Connection> pool) {
            this.obj = obj;
            this.pool = pool;
        }

        public static Connection getProxy(Object o, LinkedList<Connection> pool) {
            Object proxed = Proxy
                    .newProxyInstance(o.getClass().getClassLoader(), new Class[]{Connection.class},
                            new ConnectionProxy(o, pool));
            return (Connection) proxed;
        }

        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            if (method.getName().equals(DEFAULT_CLOSE_METHOD)) {
                synchronized (pool) {
                    pool.add((Connection) proxy);
                    pool.notify();
                }
                return null;
            } else {
                return method.invoke(obj, args);
            }
        }
    }

创建JdbcPoolConfiguration类，注册template bean

@Slf4j
@Configuration
@Component
public class KylinJdbcPoolConfiguration implements BeanFactoryPostProcessor, EnvironmentAware {

    private ConfigurableEnvironment environment;

    @Value("${kylin.decrypt}")
    private boolean decrypt = false;

    private final static String prefixName = "kylin";

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        KylinSqlProperties properties = new KylinSqlProperties();
        properties.setUserName("xxxxx");
        properties.setPassword("xxxx");
        properties.setConnectionUrl("xxxx");
        properties.setDecrypt(decrypt);
        createDataSourceBean(beanFactory, properties);
    }

    public void createDataSourceBean(ConfigurableListableBeanFactory beanFactory,
                                     KylinSqlProperties sqlProperties) {

        DataSource baseDataSource = new KylinDataSource(sqlProperties);
        register(beanFactory, new JdbcTemplate(baseDataSource), prefixName + "JdbcTemplateFactory", prefixName);
    }

    private void register(ConfigurableListableBeanFactory beanFactory, Object bean, String name,
                          String alias) {
        beanFactory.registerSingleton(name, bean);
        if (!beanFactory.containsSingleton(alias)) {
            beanFactory.registerAlias(name, alias);
        }
    }

    @Override
    public void setEnvironment(Environment environment) {
        this.environment = (ConfigurableEnvironment) environment;
    }

}

RowMapper实现

public class CommonBeanPropertyRowMapper<T> implements RowMapper<T> {

    protected final Log logger = LogFactory.getLog(this.getClass());
    private Class<T> mappedClass;
    private boolean checkFullyPopulated = false;
    private boolean primitivesDefaultedForNullValue = false;
    private ConversionService conversionService = DefaultConversionService.getSharedInstance();
    private Map<String, PropertyDescriptor> mappedFields;
    private Set<String> mappedProperties;

    public CommonBeanPropertyRowMapper() {
    }

    public CommonBeanPropertyRowMapper(Class<T> mappedClass) throws Exception {
        this.initialize(mappedClass);
    }

    public CommonBeanPropertyRowMapper(Class<T> mappedClass, boolean checkFullyPopulated)
            throws Exception {
        this.initialize(mappedClass);
        this.checkFullyPopulated = checkFullyPopulated;
    }

    public void setMappedClass(Class<T> mappedClass) throws Exception {
        if (this.mappedClass == null) {
            this.initialize(mappedClass);
        } else if (this.mappedClass != mappedClass) {
            throw new InvalidDataAccessApiUsageException(
                    "The mapped class can not be reassigned to map to " + mappedClass
                            + " since it is already providing mapping for " + this.mappedClass);
        }

    }

    public final Class<T> getMappedClass() {
        return this.mappedClass;
    }

    public void setCheckFullyPopulated(boolean checkFullyPopulated) {
        this.checkFullyPopulated = checkFullyPopulated;
    }

    public boolean isCheckFullyPopulated() {
        return this.checkFullyPopulated;
    }

    public void setPrimitivesDefaultedForNullValue(boolean primitivesDefaultedForNullValue) {
        this.primitivesDefaultedForNullValue = primitivesDefaultedForNullValue;
    }

    public boolean isPrimitivesDefaultedForNullValue() {
        return this.primitivesDefaultedForNullValue;
    }

    public void setConversionService(ConversionService conversionService) {
        this.conversionService = conversionService;
    }

    public ConversionService getConversionService() {
        return this.conversionService;
    }

    protected void initialize(Class<T> mappedClass) throws Exception {
        this.mappedClass = mappedClass;
        this.mappedFields = new HashMap();
        this.mappedProperties = new HashSet();
        PropertyDescriptor[] pds = BeanUtils.getPropertyDescriptors(mappedClass);
        PropertyDescriptor[] var3 = pds;
        int var4 = pds.length;

        for (int var5 = 0; var5 < var4; ++var5) {
            PropertyDescriptor pd = var3[var5];
            if (pd.getWriteMethod() != null) {
                Field field = mappedClass.getDeclaredField(pd.getName());
                SerializedName annotation = field.getAnnotation(SerializedName.class);
                if (annotation != null) {
                    this.mappedFields.put(annotation.value(), pd);
                } else {

                    this.mappedFields.put(this.lowerCaseName(pd.getName()), pd);
                    String underscoredName = this.underscoreName(pd.getName());
                    if (!this.lowerCaseName(pd.getName()).equals(underscoredName)) {
                        this.mappedFields.put(underscoredName, pd);
                    }
                }

                this.mappedProperties.add(pd.getName());
            }
        }
    }

    protected String underscoreName(String name) {
        if (!StringUtils.hasLength(name)) {
            return "";
        } else {
            StringBuilder result = new StringBuilder();
            result.append(this.lowerCaseName(name.substring(0, 1)));

            for (int i = 1; i < name.length(); ++i) {
                String s = name.substring(i, i + 1);
                String slc = this.lowerCaseName(s);
                if (!s.equals(slc)) {
                    result.append("_").append(slc);
                } else {
                    result.append(s);
                }
            }

            return result.toString();
        }
    }

    protected String lowerCaseName(String name) {
        return name.toLowerCase(Locale.US);
    }

    @Override
    public T mapRow(ResultSet rs, int rowNumber) throws SQLException {
        Assert.state(this.mappedClass != null, "Mapped class was not specified");
        T mappedObject = BeanUtils.instantiateClass(this.mappedClass);
        BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(mappedObject);
        this.initBeanWrapper(bw);
        ResultSetMetaData rsmd = rs.getMetaData();
        int columnCount = rsmd.getColumnCount();
        HashSet populatedProperties = this.isCheckFullyPopulated() ? new HashSet() : null;

        for (int index = 1; index <= columnCount; ++index) {
            String column = JdbcUtils.lookupColumnName(rsmd, index);
            String field = this.lowerCaseName(column.replaceAll(" ", ""));
            PropertyDescriptor pd = (PropertyDescriptor) this.mappedFields.get(field);
            if (pd == null) {
                if (rowNumber == 0 && this.logger.isDebugEnabled()) {
                    this.logger.debug(
                            "No property found for column \'" + column + "\' mapped to field \'" + field + "\'");
                }
            } else {
                try {
                    Object ex = this.getColumnValue(rs, index, pd);
                    if (rowNumber == 0 && this.logger.isDebugEnabled()) {
                        this.logger.debug(
                                "Mapping column \'" + column + "\' to property \'" + pd.getName() + "\' of type \'"
                                        + ClassUtils
                                        .getQualifiedName(pd.getPropertyType()) + "\'");
                    }

                    try {
                        bw.setPropertyValue(pd.getName(), ex);
                    } catch (TypeMismatchException var14) {
                        if (ex != null || !this.primitivesDefaultedForNullValue) {
                            throw var14;
                        }

                        if (this.logger.isDebugEnabled()) {
                            this.logger.debug(
                                    "Intercepted TypeMismatchException for row " + rowNumber + " and column \'"
                                            + column + "\' with null value when setting property \'" + pd.getName()
                                            + "\' of type \'" + ClassUtils.getQualifiedName(pd.getPropertyType())
                                            + "\' on object: " + mappedObject, var14);
                        }
                    }

                    if (populatedProperties != null) {
                        populatedProperties.add(pd.getName());
                    }
                } catch (NotWritablePropertyException var15) {
                    throw new DataRetrievalFailureException(
                            "Unable to map column \'" + column + "\' to property \'" + pd.getName() + "\'",
                            var15);
                }
            }
        }

        if (populatedProperties != null && !populatedProperties.equals(this.mappedProperties)) {
            throw new InvalidDataAccessApiUsageException(
                    "Given ResultSet does not contain all fields necessary to populate object of class ["
                            + this.mappedClass.getName() + "]: " + this.mappedProperties);
        } else {
            return mappedObject;
        }
    }

    protected void initBeanWrapper(BeanWrapper bw) {
        ConversionService cs = this.getConversionService();
        if (cs != null) {
            bw.setConversionService(cs);
        }

    }

    protected Object getColumnValue(ResultSet rs, int index, PropertyDescriptor pd)
            throws SQLException {
        return JdbcUtils.getResultSetValue(rs, index, pd.getPropertyType());
    }

    public static <T> org.springframework.jdbc.core.BeanPropertyRowMapper<T> newInstance(
            Class<T> mappedClass) {
        return new org.springframework.jdbc.core.BeanPropertyRowMapper(mappedClass);
    }
}

RowMapper子类

public class RowMapper<T> extends CommonBeanPropertyRowMapper<T> {

    private List<MapperPlugin> mapperPlugins;

    private RowMapper(Class<T> tClass, List<MapperPlugin> mapperPlugins) throws Exception {
        super(tClass);
        this.mapperPlugins = mapperPlugins;
    }

    @Override
    protected Object getColumnValue(ResultSet rs, int index, PropertyDescriptor pd)
            throws SQLException {
        Object object = rs.getObject(index);
        return mapperPlugins.stream()
                .filter(mapperPlugin -> mapperPlugin.test(pd))
                .map(mapperPlugin -> mapperPlugin.getColumnValue(object, pd))
                .findFirst()
                .orElse(super.getColumnValue(rs, index, pd));
    }

    public static <T> RowMapper<T> getDefault(Class<T> tClass) {
        return RowMapper.<T>builder().tClass(tClass)
                .mapperPlugins(JSONObjectPlugin)
                .mapperPlugins(ListPlugin)
                .mapperPlugins(SetPlugin)
                .mapperPlugins(MapPlugin)
                .mapperPlugins(EnumPlugin)
                .mapperPlugins(JsonPlugin)
                .build();
    }

    public static <T> RowMapper<T> withDefault(Class<T> tClass, MapperPlugin... mapperPlugins) {
        RhllorRowMapperBuilder<T> builder = RowMapper.<T>builder().tClass(tClass);
        for (final MapperPlugin mapperPlugin : mapperPlugins) {
            builder.mapperPlugins(mapperPlugin);
        }
        return builder
                .mapperPlugins(JSONObjectPlugin)
                .mapperPlugins(ListPlugin)
                .mapperPlugins(SetPlugin)
                .mapperPlugins(MapPlugin)
                .mapperPlugins(EnumPlugin)
                .mapperPlugins(JsonPlugin)
                .build();
    }

    public static <T> RowMapper.RhllorRowMapperBuilder<T> builder() {
        return new RowMapper.RhllorRowMapperBuilder<>();
    }

    public static class RhllorRowMapperBuilder<T> {

        private Class<T> tClass;
        private ArrayList<MapperPlugin> mapperPlugins;

        RhllorRowMapperBuilder() {
        }

        public RowMapper.RhllorRowMapperBuilder<T> tClass(Class<T> tClass) {
            this.tClass = tClass;
            return this;
        }

        public RowMapper.RhllorRowMapperBuilder<T> mapperPlugins(MapperPlugin mapperPlugin) {
            if (this.mapperPlugins == null) {
                this.mapperPlugins = new ArrayList();
            }
            this.mapperPlugins.add(mapperPlugin);
            return this;
        }

        public RowMapper<T> build() {
            List<MapperPlugin> mapperPlugins;
            switch (this.mapperPlugins == null ? 0 : this.mapperPlugins.size()) {
                case 0:
                    mapperPlugins = Collections.emptyList();
                    break;
                case 1:
                    mapperPlugins = Collections.singletonList(this.mapperPlugins.get(0));
                    break;
                default:
                    mapperPlugins = Collections.unmodifiableList(new ArrayList<>(this.mapperPlugins));
            }
            try {
                return new RowMapper<>(this.tClass, mapperPlugins);
            } catch (Exception ex) {
                ex.printStackTrace();
            }

            return null;
        }

        @Override
        public String toString() {
            return "PrestoRowMapper.KylinRowMapperBuilder(tClass=" + this.tClass + ", mapperPlugins="
                    + this.mapperPlugins + ")";
        }
    }


}

MapperPlugin

public class MapperPlugin {

    private static final Function<Object, String> bytes2UTF8String =
            bytes -> bytes instanceof String ? bytes.toString() :
                    new String((byte[]) bytes, Charset.forName("UTF-8"));

    private static final Function<PropertyDescriptor, Class> pd2Generic =
            pd -> getCollectionGeneric(pd.getReadMethod());


    private final Predicate<PropertyDescriptor> predicate;
    private final ColumnValue columnValue;

    private MapperPlugin(Predicate<PropertyDescriptor> predicate,
                         ColumnValue columnValue) {
        this.predicate = predicate;
        this.columnValue = columnValue;
    }

    boolean test(PropertyDescriptor pd) {
        return predicate.test(pd);
    }

    Object getColumnValue(Object object, PropertyDescriptor pd) {
        return columnValue.get(object, pd);
    }

    public static MapperPluginsBuilder of(Predicate<PropertyDescriptor> predicate) {
        return new MapperPluginsBuilder(predicate);
    }

    public static MapperPluginsBuilder ofNot(Predicate<PropertyDescriptor> predicate) {
        return of(predicate.negate());
    }

    public static MapperPluginsBuilder of(Class clazz) {
        return of(pd -> clazz.isAssignableFrom(pd.getPropertyType()));
    }

    @FunctionalInterface
    public interface ColumnValue {

        Object get(Object object, PropertyDescriptor pd);
    }

    public static class MapperPluginsBuilder {

        Predicate<PropertyDescriptor> predicate;

        public MapperPluginsBuilder(Predicate<PropertyDescriptor> predicate) {
            this.predicate = predicate;
        }

        public MapperPlugin columnValue(ColumnValue columnValue) {
            return new MapperPlugin(predicate, columnValue);
        }
    }

    static final MapperPlugin JsonPlugin =
            MapperPlugin.ofNot(pd -> pd.getPropertyType().isPrimitive() ||
                    Primitives.isWrapperType(pd.getPropertyType()) ||
                    String.class.isAssignableFrom(pd.getPropertyType()) ||
                    Date.class.isAssignableFrom(pd.getPropertyType()))
                    .columnValue((object, pd) ->
                            Optional.ofNullable(object)
                                    .map(bytes2UTF8String)
                                    .map(json -> JSON.parseObject(json, pd.getPropertyType()))
                                    .orElse(null));

    static final MapperPlugin JSONObjectPlugin =
            MapperPlugin.of(JSONObject.class)
                    .columnValue((object, pd) ->
                            Optional.ofNullable(object)
                                    .map(bytes2UTF8String)
                                    .map(JSONObject::parseObject)
                                    .orElse(new JSONObject()));

    static final MapperPlugin ListPlugin =
            MapperPlugin.of(List.class)
                    .columnValue((object, pd) ->
                            Optional.ofNullable(object)
                                    .map(bytes2UTF8String)
                                    .map(json -> JSON.parseArray(json, pd2Generic.apply(pd)))
                                    .orElse(new ArrayList<>()));

    static final MapperPlugin SetPlugin =
            MapperPlugin.of(Set.class)
                    .columnValue((object, pd) ->
                            Optional.ofNullable(object)
                                    .map(bytes2UTF8String)
                                    .map(json -> JSON.parseArray(json, pd2Generic.apply(pd)))
                                    .map(list -> Sets.newHashSet(List.class.cast(list)))
                                    .orElse(new HashSet<>()));

    static final MapperPlugin MapPlugin =
            MapperPlugin.of(Map.class)
                    .columnValue((object, pd) ->
                            Optional.ofNullable(object)
                                    .map(bytes2UTF8String)
                                    .map(json -> JSONObject.parseObject(json, Map.class))
                                    .orElse(new HashMap<>()));

    static final MapperPlugin EnumPlugin =
            MapperPlugin.of(Enum.class)
                    .columnValue((o, pd) -> {
                        try {
                            if (o == null) {
                                return null;
                            }
                            if (o instanceof Number) {
                                Number number = (Number) o;
                                Method method = pd.getPropertyType()
                                        .getMethod("valueByIndex", Integer.TYPE);
                                return method.invoke(null, number.intValue());
                            } else {
                                String val = o.toString();
                                Method method = pd.getPropertyType().getMethod("fromString", String.class);
                                return method.invoke(null, val);
                            }
                        } catch (NoSuchMethodException e) {
                            throw new RuntimeException(
                                    "getColumnValue error, NoSuchMethod : valueByIndex or fromString", e);
                        } catch (InvocationTargetException e) {
                            throw new RuntimeException(
                                    "getColumnValue error, InvocationTargetException ", e);
                        } catch (IllegalAccessException e) {
                            throw new RuntimeException(
                                    "getColumnValue error, IllegalAccessException ", e);
                        }
                    });

    private static Class<?> getCollectionGeneric(Method method) {
        if (Collection.class.isAssignableFrom(method.getReturnType())) {
            Type fc = method.getGenericReturnType();
            if (fc == null) {
                return Object.class;
            }
            if (fc instanceof ParameterizedType) {
                ParameterizedType pt = (ParameterizedType) fc;
                return (Class) pt.getActualTypeArguments()[0];
            }
            return Object.class;
        }
        return Object.class;
    }

}

具体使用

@Component
@Log4j2
public class MetricDaoImpl {
   
    @Resource(name = "kylinJdbcTemplateFactory")
    private JdbcTemplate kylinJdbcTemplate;

    public List<TotalModelMetricEntity> getDistinctIds() {
        StringBuilder sqlBuilder = new StringBuilder()
                .append(" select * ")
                .append(" from LOG_DID_VIEW ")
                .append(" ORDER BY DT ,total DESC limit 1000");
        log.info(sqlBuilder);
        return kylinJdbcTemplate.query(sqlBuilder.toString(), RowMapper.getDefault(TotalModelMetricEntity.class));
    }

综上我们就完成了对Kylin JDBC的封装，同样的如Presto等其他支持JDBC的查询引擎封装方式类似。

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