Cassandra客户端连接的说明---Java版

在使用Java客户端调用之前，我们需要通过Cassandra CLI在服务器上创建相应的keyspace和column family.

参考：http://wiki.apache.org/cassandra/CassandraCli

进入cassandra/bin目录，运行指令如下

./cassandra-cli

connect 192.168.11.124/9160;

create keyspace LiftDNA_KeySpace;

use LiftDNA_KeySpace;

create column family User_ColumnFamily with comparator = UTF8Type;

或者建立counter:

create column family User_SuperCounter with default_validation_class = CounterColumnType;

如果需要建立其他类型的簇，参见本文底部链接。

然后运行一下Java代码：

import java.util.List;
import java.io.UnsupportedEncodingException;

import java.nio.ByteBuffer;
import java.util.Random;
import org.apache.cassandra.thrift.AuthenticationException;
import org.apache.cassandra.thrift.AuthorizationException;
import org.apache.cassandra.thrift.Cassandra;
import org.apache.cassandra.thrift.Column;
import org.apache.cassandra.thrift.ColumnOrSuperColumn;
import org.apache.cassandra.thrift.ColumnParent;
import org.apache.cassandra.thrift.ConsistencyLevel;
import org.apache.cassandra.thrift.InvalidRequestException;
import org.apache.cassandra.thrift.KeyRange;
import org.apache.cassandra.thrift.KeySlice;
import org.apache.cassandra.thrift.NotFoundException;
import org.apache.cassandra.thrift.SlicePredicate;
import org.apache.cassandra.thrift.SliceRange;
import org.apache.cassandra.thrift.TimedOutException;
import org.apache.cassandra.thrift.UnavailableException;
import org.apache.thrift.transport.TTransport;
import org.apache.thrift.transport.TFramedTransport;
import org.apache.thrift.transport.TSocket;
import org.apache.thrift.protocol.TProtocol;
import org.apache.thrift.protocol.TBinaryProtocol;
import org.apache.thrift.TException;
import org.apache.thrift.transport.TTransportException;

public class Test {

    public static void main(String[] args) throws TTransportException, UnsupportedEncodingException, InvalidRequestException, NotFoundException, UnavailableException, TimedOutException, TException, AuthenticationException, AuthorizationException {

        TTransport tr = new TFramedTransport(new TSocket("192.168.11.124", 9160));
        TProtocol proto = new TBinaryProtocol(tr);

        Cassandra.Client client = new Cassandra.Client(proto);
        tr.open();
        String keyspace = "LiftDNA_KeySpace";
        client.set_keyspace(keyspace);
        //record id
        String key_user_id = "1";
        String columnFamily = "User_ColumnFamily";
        // insert data
        long timestamp = System.currentTimeMillis();
        Random r = new Random(timestamp);
        Column nameColumn = new Column(ByteBuffer.wrap("name".getBytes()));
        nameColumn.setValue(Long.toHexString(r.nextLong()).getBytes());
        nameColumn.setTimestamp(timestamp);

        Column ageColumn = new Column(ByteBuffer.wrap("age".getBytes()));
        ageColumn.setValue(Long.toHexString(r.nextLong()).getBytes());
        ageColumn.setTimestamp(timestamp);

        ColumnParent columnParent = new ColumnParent(columnFamily);
        client.insert(ByteBuffer.wrap(key_user_id.getBytes()), columnParent,nameColumn,ConsistencyLevel.ALL) ;
        client.insert(ByteBuffer.wrap(key_user_id.getBytes()), columnParent,ageColumn,ConsistencyLevel.ALL);

        //Gets column by key
        SlicePredicate predicate = new SlicePredicate();
        predicate.setSlice_range(new SliceRange(ByteBuffer.wrap(new byte[0]), ByteBuffer.wrap(new byte[0]), false, 100));
        List columnsByKey = client.get_slice(ByteBuffer.wrap(key_user_id.getBytes()), columnParent, predicate, ConsistencyLevel.ALL);
        System.out.println(columnsByKey);

        
        //Get all keys
        KeyRange keyRange = new KeyRange(100);
        keyRange.setStart_key(new byte[0]);
        keyRange.setEnd_key(new byte[0]);
        List keySlices = client.get_range_slices(columnParent, predicate, keyRange, ConsistencyLevel.ONE);
        System.out.println(keySlices.size());
        System.out.println(keySlices);
        for (KeySlice ks : keySlices) {
            System.out.println(new String(ks.getKey()));
        }
        tr.close();
    }
}

所需Java包：

apache-cassandra-1.0.6.jar

apache-cassandra-clientutil-1.0.6.jar

apache-cassandra-thrift-1.0.6.jar

libthrift-0.6.jar

slf4j-api-1.6.1.jar

所有第三方Jar包均可在Cassandra/lib里找到。

此外，我们还可以使用Hector http://rantav.github.com/hector/build/html/index.html

https://github.com/rantav/hector

Hector提供了对Cassandra操作的更高级的封装。

https://github.com/rantav/hector/wiki/Getting-started-%285-minutes%29

连接测试：

import java.util.List;

import me.prettyprint.cassandra.service.CassandraHostConfigurator;
import me.prettyprint.cassandra.service.ThriftCluster;
import me.prettyprint.hector.api.ddl.KeyspaceDefinition;

public class Test {

    public static void main(String[] args) {
        
        CassandraHostConfigurator cassandraHostConfigurator = new CassandraHostConfigurator("192.168.11.124:9160");
        ThriftCluster cassandraCluster = new ThriftCluster("Test Cluster", cassandraHostConfigurator);
        List keyspaces = cassandraCluster.describeKeyspaces();
        for (KeyspaceDefinition keyspaceDefinition : keyspaces) {
            System.out.println(keyspaceDefinition.getName());
        }
    }
}

参考代码：

https://github.com/rantav/hector/blob/master/core/src/test/java/me/prettyprint/cassandra/service/CassandraClusterTest.java#L84-157

其他测试代码：

import static me.prettyprint.hector.api.factory.HFactory.createColumn;
import static me.prettyprint.hector.api.factory.HFactory.createColumnQuery;
import static me.prettyprint.hector.api.factory.HFactory.createKeyspace;
import static me.prettyprint.hector.api.factory.HFactory.createMultigetSliceQuery;
import static me.prettyprint.hector.api.factory.HFactory.createMutator;
import static me.prettyprint.hector.api.factory.HFactory.getOrCreateCluster;

import java.util.HashMap;
import java.util.Map;

import me.prettyprint.cassandra.serializers.StringSerializer;
import me.prettyprint.hector.api.Cluster;
import me.prettyprint.hector.api.Keyspace;
import me.prettyprint.hector.api.Serializer;
import me.prettyprint.hector.api.beans.HColumn;
import me.prettyprint.hector.api.beans.Rows;
import me.prettyprint.hector.api.exceptions.HectorException;
import me.prettyprint.hector.api.mutation.Mutator;
import me.prettyprint.hector.api.query.ColumnQuery;
import me.prettyprint.hector.api.query.MultigetSliceQuery;
import me.prettyprint.hector.api.query.QueryResult;

/**
 * Thread Safe
 * @author Ran Tavory
 *
 */
public class ExampleDaoV2 {

  private final static String KEYSPACE = "LiftDNA_KeySpace";
  private final static String HOST_PORT = "192.168.11.124:9160";
  private final static String CF_NAME = "User_ColumnFamily";
  /** Column name where values are stored */
  private final static String COLUMN_NAME = "v";
  private final StringSerializer serializer = StringSerializer.get();

  private final Keyspace keyspace;

  public static void main(String[] args) throws HectorException {
    Cluster c = getOrCreateCluster("Test Cluster", HOST_PORT);
    ExampleDaoV2 ed = new ExampleDaoV2(createKeyspace(KEYSPACE, c));
    ed.insert("key1", "value1", StringSerializer.get());

    System.out.println(ed.get("key1", StringSerializer.get()));
  }

  public ExampleDaoV2(Keyspace keyspace) {
    this.keyspace = keyspace;
  }

  /**
   * Insert a new value keyed by key
   *
   * @param key   Key for the value
   * @param value the String value to insert
   */
  public  void insert(final K key, final String value, Serializer keySerializer) {
    createMutator(keyspace, keySerializer).insert(
        key, CF_NAME, createColumn(COLUMN_NAME, value, serializer, serializer));
  }

  /**
   * Get a string value.
   *
   * @return The string value; null if no value exists for the given key.
   */
  public  String get(final K key, Serializer keySerializer) throws HectorException {
    ColumnQuery q = createColumnQuery(keyspace, keySerializer, serializer, serializer);
    QueryResult> r = q.setKey(key).
        setName(COLUMN_NAME).
        setColumnFamily(CF_NAME).
        execute();
    HColumn c = r.get();
    return c == null ? null : c.getValue();
  }

  /**
   * Get multiple values
   * @param keys
   * @return
   */
  public  Map getMulti(Serializer keySerializer, K... keys) {
    MultigetSliceQuery q = createMultigetSliceQuery(keyspace, keySerializer, serializer, serializer);
    q.setColumnFamily(CF_NAME);
    q.setKeys(keys);
    q.setColumnNames(COLUMN_NAME);

    QueryResult> r = q.execute();
    Rows rows = r.get();
    Map ret = new HashMap(keys.length);
    for (K k: keys) {
      HColumn c = rows.getByKey(k).getColumnSlice().getColumnByName(COLUMN_NAME);
      if (c != null && c.getValue() != null) {
        ret.put(k, c.getValue());
      }
    }
    return ret;
  }

  /**
   * Insert multiple values
   */
  public  void insertMulti(Map keyValues, Serializer keySerializer) {
    Mutator m = createMutator(keyspace, keySerializer);
    for (Map.Entry keyValue: keyValues.entrySet()) {
      m.addInsertion(keyValue.getKey(), CF_NAME,
          createColumn(COLUMN_NAME, keyValue.getValue(), keyspace.createClock(), serializer, serializer));
    }
    m.execute();
  }

  /**
   * Delete multiple values
   */
  public  void delete(Serializer keySerializer, K... keys) {
    Mutator m = createMutator(keyspace, keySerializer);
    for (K key: keys) {
      m.addDeletion(key, CF_NAME,  COLUMN_NAME, serializer);
    }
    m.execute();
  }
}

使用CQL查询数据(基于Hector)

Cluster c = getOrCreateCluster("Test Cluster", HOST_PORT);
Keyspace keyspace = createKeyspace("LiftDNA_KeySpace", c);
StringSerializer serializer = StringSerializer.get();
CqlQuery cqlQuery = new CqlQuery(keyspace, serializer, serializer, serializer);
cqlQuery.setQuery("select * from User_ColumnFamily");
QueryResult> result = cqlQuery.execute();
System.out.println(result.get().getByKey("rkey").getColumnSlice().getColumnByName("ckey").getValue());

参考网址： https://github.com/rantav/hector/wiki/Using-CQL

A little piece of code to increment counters of a superColumn

String key = "keyOfRow"; 
String superColumnFamily = "foo"; 
String superColumnName ="bar"; 
StringSerializer ss = StringSerializer.get(); 
// let's insert a couple of counter columns in a superColumn 
String columnName1="aaa"; 
String columnName2="bbb"; 
List > myCounters = new 
ArrayList>(); 
myCounters.add(HFactory.createCounterColumn(columnName1, 1L)); 
myCounters.add(HFactory.createCounterColumn(columnName2, 42L)); 
Mutator mutator = HFactory.createMutator(keyspace, 
StringSerializer.get()); 
mutator.insertCounter(key,superColumnFamily , 
HFactory.createCounterSuperColumn(superColumnName, myCounters, ss, ss)); 
mutator.execute();

其他资料：

http://wingware.iteye.com/blog/1144584

http://cmzx3444.iteye.com/blog/663800

http://www.cnblogs.com/mobile/archive/2010/06/12/1757272.html

http://www.360doc.com/content/11/0309/00/5728962_99408528.shtml

其他客户端工具：

http://wiki.apache.org/cassandra/ClientOptions

最后，我们还需要重新去理解一下Cassandra的数据结构。

http://wiki.apache.org/cassandra/DataModel

附加内容：几个Cassandra建列族的例子

/*This file contains an example Keyspace that can be created using the

cassandra-cli command line interface as follows.

bin/cassandra-cli -host localhost --file conf/schema-sample.txt

The cassandra-cli includes online help that explains the statements below. You can

accessed the help without connecting to a running cassandra instance by starting the

client and typing "help;"

*/

create keyspace Keyspace1

    with strategy_options=[{replication_factor:1}]

    and placement_strategy = 'org.apache.cassandra.locator.SimpleStrategy';

use Keyspace1;

create column family Standard1

    with comparator = BytesType

    and keys_cached = 10000

    and rows_cached = 1000

    and row_cache_save_period = 0

    and key_cache_save_period = 3600

    and memtable_flush_after = 59

    and memtable_throughput = 255

    and memtable_operations = 0.29;

create column family Standard2

    with comparator = UTF8Type

    and read_repair_chance = 0.1

    and keys_cached = 100

    and gc_grace = 0

    and min_compaction_threshold = 5

    and max_compaction_threshold = 31;

create column family StandardByUUID1

    with comparator = TimeUUIDType;

create column family Super1

    with column_type = Super

    and comparator = BytesType

    and subcomparator = BytesType;

create column family Super2

    with column_type = Super

    and subcomparator = UTF8Type

    and rows_cached = 10000

    and keys_cached = 50

    and comment = 'A column family with supercolumns, whose column and subcolumn names are UTF8 strings';

create column family Super3

    with column_type = Super

    and comparator = LongType

    and comment = 'A column family with supercolumns, whose column names are Longs (8 bytes)';

create column family Indexed1

    with comparator = UTF8Type

    and default_validation_class = LongType

    and column_metadata = [{

        column_name : birthdate,

        validation_class : LongType,

        index_name : birthdate_idx,

        index_type : 0}

    ];

create column family Counter1

    with default_validation_class = CounterColumnType;

create column family SuperCounter1

    with column_type = Super

    and default_validation_class = CounterColumnType;