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A driver for Apache Cassandra 1.2+ that works exclusively with the Cassandra Query Language version 3
(CQL3) and Cassandra's binary protocol.
/*
* Copyright (C) 2012-2015 DataStax Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.datastax.driver.core;
import com.datastax.driver.core.exceptions.InvalidTypeException;
import com.datastax.driver.core.exceptions.UnsupportedProtocolVersionException;
import com.datastax.driver.core.querybuilder.BuiltStatement;
import com.datastax.driver.core.schemabuilder.SchemaStatement;
import java.nio.ByteBuffer;
import java.util.Map;
/**
* A regular (non-prepared and non batched) CQL statement.
*
* This class represents a query string along with query options (and optionally
* binary values, see {@code getValues}). It can be extended but {@link SimpleStatement}
* is provided as a simple implementation to build a {@code RegularStatement} directly
* from its query string.
*/
public abstract class RegularStatement extends Statement {
/**
* Creates a new RegularStatement.
*/
protected RegularStatement() {
}
/**
* Returns the query string for this statement.
*
* It is important to note that the query string is merely
* a CQL representation of this statement, but it does
* not convey all the information stored in {@link Statement}
* objects.
*
* For example, {@link Statement} objects carry numerous protocol-level
* settings, such as the {@link Statement#getConsistencyLevel() consistency level} to use,
* or the {@link Statement#isIdempotent() idempotence flag}, among others.
* None of these settings will be included in the resulting query string.
*
* Similarly, if values have been set on this statement because
* it has bind markers, these values will not appear in the resulting query string.
*
* Note: the consistency level was conveyed at CQL level in older versions
* of the CQL grammar, but since CASSANDRA-4734
* it is now a protocol-level setting and consequently does not appear in the query string.
*
* @param codecRegistry the codec registry that will be used if the actual
* implementation needs to serialize Java objects in the
* process of generating the query. Note that it might be
* possible to use the no-arg {@link #getQueryString()}
* depending on the type of statement this is called on.
* @return a valid CQL query string.
* @see #getQueryString()
*/
public abstract String getQueryString(CodecRegistry codecRegistry);
/**
* Returns the query string for this statement.
*
* This method calls {@link #getQueryString(CodecRegistry)} with {@link CodecRegistry#DEFAULT_INSTANCE}.
* Whether you should use this or the other variant depends on the type of statement this is
* called on:
*
* - for a {@link SimpleStatement} or {@link SchemaStatement}, the codec registry isn't
* actually needed, so it's always safe to use this method;
* - for a {@link BuiltStatement} you can use this method if you use no custom codecs, or if
* your custom codecs are registered with the default registry. Otherwise, use the other method and
* provide the registry that contains your codecs (see {@link BuiltStatement} for more explanations
* on why this is so);
* - for a {@link BatchStatement}, use the first rule if it contains no built statements,
* or the second rule otherwise.
*
*
* @return a valid CQL query string.
*/
public String getQueryString() {
return getQueryString(CodecRegistry.DEFAULT_INSTANCE);
}
/**
* The positional values to use for this statement.
*
* A statement can use either positional or named values, but not both. So if this method returns a non-null result,
* {@link #getNamedValues(ProtocolVersion, CodecRegistry)} will return {@code null}.
*
* Values for a RegularStatement (i.e. if either method does not return
* {@code null}) are not supported with the native protocol version 1: you
* will get an {@link UnsupportedProtocolVersionException} when submitting
* one if version 1 of the protocol is in use (i.e. if you've forced version
* 1 through {@link Cluster.Builder#withProtocolVersion} or you use
* Cassandra 1.2).
*
* @param protocolVersion the protocol version that will be used to serialize
* the values.
* @param codecRegistry the codec registry that will be used to serialize the
* values.
* @throws InvalidTypeException if one of the values is not of a type
* that can be serialized to a CQL3 type
* @see SimpleStatement#SimpleStatement(String, Object...)
*/
public abstract ByteBuffer[] getValues(ProtocolVersion protocolVersion, CodecRegistry codecRegistry);
/**
* The named values to use for this statement.
*
* A statement can use either positional or named values, but not both. So if this method returns a non-null result,
* {@link #getValues(ProtocolVersion, CodecRegistry)} will return {@code null}.
*
* Values for a RegularStatement (i.e. if either method does not return
* {@code null}) are not supported with the native protocol version 1: you
* will get an {@link UnsupportedProtocolVersionException} when submitting
* one if version 1 of the protocol is in use (i.e. if you've forced version
* 1 through {@link Cluster.Builder#withProtocolVersion} or you use
* Cassandra 1.2).
*
* @param protocolVersion the protocol version that will be used to serialize
* the values.
* @param codecRegistry the codec registry that will be used to serialize the
* values.
* @return the named values.
* @throws InvalidTypeException if one of the values is not of a type
* that can be serialized to a CQL3 type
* @see SimpleStatement#SimpleStatement(String, Map)
*/
public abstract Map getNamedValues(ProtocolVersion protocolVersion, CodecRegistry codecRegistry);
/**
* Whether or not this statement has values, that is if {@code getValues}
* will return {@code null} or not.
*
* @param codecRegistry the codec registry that will be used if the actual
* implementation needs to serialize Java objects in the
* process of determining if the query has values.
* Note that it might be possible to use the no-arg
* {@link #hasValues()} depending on the type of
* statement this is called on.
* @return {@code false} if both {@link #getValues(ProtocolVersion, CodecRegistry)}
* and {@link #getNamedValues(ProtocolVersion, CodecRegistry)} return {@code null}, {@code true}
* otherwise.
* @see #hasValues()
*/
public abstract boolean hasValues(CodecRegistry codecRegistry);
/**
* Whether this statement uses named values.
*
* @return {@code false} if {@link #getNamedValues(ProtocolVersion, CodecRegistry)} returns {@code null},
* {@code true} otherwise.
*/
public abstract boolean usesNamedValues();
/**
* Whether or not this statement has values, that is if {@code getValues}
* will return {@code null} or not.
*
* This method calls {@link #hasValues(CodecRegistry)} with {@link ProtocolVersion#NEWEST_SUPPORTED}.
* Whether you should use this or the other variant depends on the type of statement this is
* called on:
*
* - for a {@link SimpleStatement} or {@link SchemaStatement}, the codec registry isn't
* actually needed, so it's always safe to use this method;
* - for a {@link BuiltStatement} you can use this method if you use no custom codecs, or if
* your custom codecs are registered with the default registry. Otherwise, use the other method and
* provide the registry that contains your codecs (see {@link BuiltStatement} for more explanations
* on why this is so);
* - for a {@link BatchStatement}, use the first rule if it contains no built statements,
* or the second rule otherwise.
*
*
* @return {@code false} if {@link #getValues} returns {@code null}, {@code true}
* otherwise.
*/
public boolean hasValues() {
return hasValues(CodecRegistry.DEFAULT_INSTANCE);
}
/**
* Returns this statement as a CQL query string.
*
* It is important to note that the query string is merely
* a CQL representation of this statement, but it does
* not convey all the information stored in {@link Statement}
* objects.
*
* See the javadocs of {@link #getQueryString()} for more information.
*
* @return this statement as a CQL query string.
* @see #getQueryString()
*/
@Override
public String toString() {
return getQueryString();
}
}