这里我们开始使用JAVA来操作cassandra数据库，而不仅限于客户端操作。关于客户端cassandra-cli和nodetool的操作，在命令行使用help命令可以获取很多帮助。

我使用的是thrift来操作数据库，这是一种较低级的方法，它直接使用最基本的API。尽管有更高级的方式来操作，但熟悉API依然是必须的，因此我们先使用thrift。

首先要在JAVA里导入包，在MyEclipse里右键工程名，选择properties，进入JavaBuildPath->Libraries，选择AddExternalJars，导入：

Apache-cassandra-1.0.8.jar

Apache-cassandra-thrift-1.0.8.jar

libthrift-0.6.jar

log4j-1.2.16.jar

slf4j-api-1.6.1.jar

slf4j-log4j12-1.6.1.jar

这些JAR包都在canssandra目录下的lib文件夹内。

下面是测试代码：

package cassandra;import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.util.List;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.ColumnPath;
import org.apache.cassandra.thrift.ConsistencyLevel;
import org.apache.cassandra.thrift.InvalidRequestException;
import org.apache.cassandra.thrift.NotFoundException;
import org.apache.cassandra.thrift.SlicePredicate;
import org.apache.cassandra.thrift.SliceRange;
import org.apache.cassandra.thrift.TBinaryProtocol;
import org.apache.cassandra.thrift.TimedOutException;
import org.apache.cassandra.thrift.UnavailableException;
import org.apache.thrift.TException;
import org.apache.thrift.protocol.TProtocol;
import org.apache.thrift.transport.TFramedTransport;
import org.apache.thrift.transport.TSocket;
import org.apache.thrift.transport.TTransport;public class TestClient
{public static void main(String[] args)throws TException, InvalidRequestException,      UnavailableException, UnsupportedEncodingException,NotFoundException, TimedOutException{//包装好的socketTTransport tr = new TFramedTransport(new TSocket("127.0.0.1",9160));TProtocol proto = new TBinaryProtocol(tr);Cassandra.Client client = new Cassandra.Client(proto);tr.open();if(!tr.isOpen()){System.out.println("failed to connect server!");return;}long temp = System.currentTimeMillis();client.set_keyspace("DEMO");//使用DEMO keyspaceColumnParent parent = new ColumnParent("Student");//column family/** 这里我们插入100万条数据到Student内* 每条数据包括id和name*/String key_user_id = "a";for(int i = 0;i < 1000000;i++){String k = key_user_id + i;//keylong timestamp = System.currentTimeMillis();//时间戳Column idColumn = new Column(toByteBuffer("id"));//column nameidColumn.setValue(toByteBuffer(i + ""));//column valueidColumn.setTimestamp(timestamp);client.insert(toByteBuffer(k), parent, idColumn, ConsistencyLevel.ONE);Column nameColumn = new Column(toByteBuffer("name"));nameColumn.setValue(toByteBuffer("student" + i));nameColumn.setTimestamp(timestamp);client.insert(toByteBuffer(k), parent, nameColumn, ConsistencyLevel.ONE);}/** 读取某条数据的单个字段*/ColumnPath path = new ColumnPath("Student");//设置读取Student的数据path.setColumn(toByteBuffer("id"));   //读取id  String key3 = "a1";//读取key为a1的那条记录System.out.println(toString(client.get(toByteBuffer(key3), path, ConsistencyLevel.ONE).column.value));/** 读取整条数据*/SlicePredicate predicate = new SlicePredicate();SliceRange sliceRange = new SliceRange(toByteBuffer(""), toByteBuffer(""), false, 10);predicate.setSlice_range(sliceRange);List<ColumnOrSuperColumn> results = client.get_slice(toByteBuffer(key3), parent, predicate, ConsistencyLevel.ONE);for (ColumnOrSuperColumn result : results){Column column = result.column;System.out.println(toString(column.name) + " -> " + toString(column.value));}long temp2 = System.currentTimeMillis();System.out.println("time: " + (temp2 - temp) + " ms");//输出耗费时间tr.close();}/** 将String转换为bytebuffer，以便插入cassandra*/public static ByteBuffer toByteBuffer(String value) throws UnsupportedEncodingException{return ByteBuffer.wrap(value.getBytes("UTF-8"));}/** 将bytebuffer转换为String*/public static String toString(ByteBuffer buffer) throws UnsupportedEncodingException{byte[] bytes = new byte[buffer.remaining()];buffer.get(bytes);return new String(bytes, "UTF-8");}
}