最近因为实验室项目需要，开始研究了hbase。然后想一次性往集群服务器上写入大量的数据，并存到hbase中，考虑到在hbase shell下只能单个数据put，这样对于批量插入数据的要求完全不合适。于是就研究起hbase的java api，然后去大量填充数据到hbase以测试查询的性能。于是，故事开始了。
首先在eclipse下写好了，如下的Java代码：
<span style="font-size:12px;">import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.Admin;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
public class testCreate {
public static void main(String[] args){
Configuration conf = HBaseConfiguration.create();
conf.set("hbase.rootdir", "hdfs://xxx-a.test.com:8020/apps/hbase/data");//使用eclipse时必须添加这个，否则无法定位
conf.set("hbase.zookeeper.quorum", "xxx-a1.test.com,xxx-a2.test.com,xxx-a3.test.com");
conf.set("hbase.zookeeper.property.clientPort", "2181");
conf.set("zookeeper.znode.parent","/hbase-unsecure");//这行代码也是后来加上的
try {
Connection conn = ConnectionFactory.createConnection(conf);
System.out.println("StartConnect...");
Admin hAdmin = conn.getAdmin();
HTableDescriptor hTableDesc = new HTableDescriptor(TableName.valueOf("Customer2"));
hTableDesc.addFamily(new HColumnDescriptor("name"));
hTableDesc.addFamily(new HColumnDescriptor("contactinfo"));
hTableDesc.addFamily(new HColumnDescriptor("address"));
hAdmin.createTable(hTableDesc);
System.out.println("Table created Successfully...");
} catch (Exception e) {
e.printStackTrace();
}
}
}</span><span style="font-size:12px;"><span style="white-space: pre;"> </span>代码写好，一堆错误。是因为缺少依赖的jar包。以下是添加的jar截图。</span>
这样jar包都是程序运行报错一点点加进去的，分享给大家可以少走冤枉路。（debug也是一种乐趣，虽然有时候想死的心都有，但是坚持找，肯定会解决的
）
此时还得配置电脑的hosts，在C:\Windows\System32\drivers\etc\目录，有一个hosts文件，在其中加上xxx-a.test.com对应的实际ip地址，这样程序运行才会访问到正确的地方，格式类似于这样xxx-a.test.com X.X.X.X。基于这样，程序是可以运行的，Java的运行日志会有如下显示：
表示连接hbase数据库成功，创建表成功。皆大欢喜。
下面说一下几个需要注意的地方：
1、conf.set("hbase.rootdir", "hdfs://xxx-a.test.com:8020/apps/hbase/data");//使用eclipse时必须添加这个，否则无法定位这句话必须要加上，通过这句配置，才能准确的定位hbase实际存储的hdfs位置，所以这里面的<span style="font-family: Arial, Helvetica, sans-serif;">xxx-a.test.com换成详细的ip地址也是可以的。</span> 2、conf.set("hbase.zookeeper.quorum", "xxx-a1.test.com,xxx-a2.test.com,xxx-a3.test.com");<span style="font-family: Helvetica, Tahoma, Arial, sans-serif; font-size: 14px; line-height: 25.2px;">Zookeeper集群的地址列表，用逗号分割。例如：</span><span style="font-family: Helvetica, Tahoma, Arial, sans-serif; font-size: 14px; line-height: 25.2px;">"xxx-a1.test.com,xxx-a2.test.com,xxx-a3.test.com</span><span style="font-size: 14px; line-height: 25.2px; font-family: Helvetica, Tahoma, Arial, sans-serif;">".默认是localhost,是给伪分布式用的。要修改才能在完全分布式的情况下使用。如果在hbase-env.sh设置了HBASE_MANAGES_ZK，这些ZooKeeper节点就会和HBase一起启动。</span><span style="font-family: Helvetica, Tahoma, Arial, sans-serif; font-size: 14px; line-height: 25.2px;"> </span>3、conf.set("hbase.zookeeper.property.clientPort", "2181");这句话是设置zookeeper监控连接的客户端的端口号是2181，这是默认的配置。 4、conf.set("zookeeper.znode.parent","/hbase-unsecure");//这行代码也是后来加上的<span style="font-family: Helvetica, Tahoma, Arial, sans-serif; line-height: 25.2px;">ZooKeeper中的HBase的根ZNode。所有的HBase的ZooKeeper会用这个目录配置相对路径。默认情况下，所有的HBase的ZooKeeper文件路径是用相对路径，所以他们会都去这个目录下面。</span><span style="font-family:Helvetica, Tahoma, Arial, sans-serif;"><span style="line-height: 25.2px;">5.没加上面那句代码之前我的报错信息一直是：</span></span><span style="font-family:Helvetica, Tahoma, Arial, sans-serif;"><span style="line-height: 25.2px;">org.apache.hadoop.hbase.client.RetriesExhaustedException: Failed after attempts=35, exceptions: Wed Aug 10 21:29:19 CST 2016, RpcRetryingCaller{globalStartTime=1470835740311, pause=100, retries=35}, org.apache.hadoop.hbase.MasterNotRunningException: org.apache.hadoop.hbase.MasterNotRunningException: Can't get connection to ZooKeeper: KeeperErrorCode = ConnectionLoss for /hbase </span></span><span style="font-family:Helvetica, Tahoma, Arial, sans-serif;"><span style="line-height: 25.2px;">at org.apache.hadoop.hbase.client.RpcRetryingCaller.callWithRetries(RpcRetryingCaller.java:157) <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.client.HBaseAdmin.executeCallable(HBaseAdmin.java:4212) <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.client.HBaseAdmin.createTableAsyncV2(HBaseAdmin.java:748) <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.client.HBaseAdmin.createTable(HBaseAdmin.java:669) <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.client.HBaseAdmin.createTable(HBaseAdmin.java:602) <span style="white-space:pre"> </span>at hbase.testCreate.main(testCreate.java:24) Caused by: org.apache.hadoop.hbase.MasterNotRunningException: org.apache.hadoop.hbase.MasterNotRunningException: Can't get connection to ZooKeeper: KeeperErrorCode = ConnectionLoss for /hbase <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation$StubMaker.makeStub(ConnectionManager.java:1535) <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation$MasterServiceStubMaker.makeStub(ConnectionManager.java:1555) <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation.getKeepAliveMasterService(ConnectionManager.java:1706) <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.client.MasterCallable.prepare(MasterCallable.java:38) <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.client.RpcRetryingCaller.callWithRetries(RpcRetryingCaller.java:134) <span style="white-space:pre"> </span>... 5 more Caused by: org.apache.hadoop.hbase.MasterNotRunningException: Can't get connection to ZooKeeper: KeeperErrorCode = ConnectionLoss for /hbase <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation.checkIfBaseNodeAvailable(ConnectionManager.java:907) <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation.access$400(ConnectionManager.java:546) <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation$StubMaker.makeStubNoRetries(ConnectionManager.java:1485) <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation$StubMaker.makeStub(ConnectionManager.java:1526) <span style="white-space:pre"> </span>... 9 more Caused by: org.apache.zookeeper.KeeperException$ConnectionLossException: KeeperErrorCode = ConnectionLoss for /hbase <span style="white-space:pre"> </span>at org.apache.zookeeper.KeeperException.create(KeeperException.java:99) <span style="white-space:pre"> </span>at org.apache.zookeeper.KeeperException.create(KeeperException.java:51) <span style="white-space:pre"> </span>at org.apache.zookeeper.ZooKeeper.exists(ZooKeeper.java:1045) <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper.exists(RecoverableZooKeeper.java:221) <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.zookeeper.ZKUtil.checkExists(ZKUtil.java:541) <span style="white-space:pre"> </span>at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation.checkIfBaseNodeAvailable(ConnectionManager.java:896) <span style="white-space:pre"> </span>... 12 more </span></span><span style="font-family:Helvetica, Tahoma, Arial, sans-serif;"><span style="line-height: 25.2px;">加上</span></span><span style="line-height: 25.2px; font-family: Helvetica, Tahoma, Arial, sans-serif;">conf.set("zookeeper.znode.parent","/hbase-unsecure");</span><span style="line-height: 25.2px; font-family: Helvetica, Tahoma, Arial, sans-serif;">就可以成功访问并操作hbase数据库。</span><span style="font-family:Helvetica, Tahoma, Arial, sans-serif;"><span style="line-height: 25.2px;">以上是个人实际学习过程的一些经验，在此记录一下，欢迎大家一起学习交流hbase相关技术！</span></span>
