Java 访问Hbase数据库
须知
Hbase数据最终是在hdfs上的，具体来说应该是在hdfs上一个叫做/hbase的目录下。具体结构如下：
所以java访问Hbase其实就是访问hdfs，所以环境搭建跟hadoop开发环境使用没什么不同。
实战部分
1.导入需要的jar包，此处在java项目引入Hbase解压后lib目录下所有jar包即可。里面提供了访问Hbase的api接口，也有与hadoop集成的客户端jar包。
2.将hbase-site.xml拷贝到classpath根目录下，这样，hbase在创建configuration对象会自动加载，hbase源码此部分：
public static Configuration addHbaseResources(Configuration conf)
{
conf.addResource("hbase-default.xml");
conf.addResource("hbase-site.xml");
checkDefaultsVersion(conf);
checkForClusterFreeMemoryLimit(conf);
return conf;
}
具体文件hbase-site.xml参照内容如下：
hbase.rootdir
hdfs://chidianwei-VirtualBox:9000/hbase
hbase.cluster.distributed
true
hbase.zookeeper.quorum
chidianwei-VirtualBox
dfs.replication
1
3.下面我们就可以写一个初始化表测试类，创建了两张表，word和stat。（其中的HbaseUtil类代码见最后一步）代码如下：
public class InitData {
public static void main(String[] args) throws IOException {
//创建一个word表，只有一个列族content
HBaseUtil.createTable("word","content");
//获取word表
HTable htable = HBaseUtil.getHTable("word");
htable.setAutoFlush(false);
//创建测试数据
List puts = new ArrayList();
Put put1 = HBaseUtil.getPut("1","content",null,"The Apache Hadoop software library is a framework");
Put put2 = HBaseUtil.getPut("2","content",null,"The common utilities that support the other Hadoop modules");
Put put3 = HBaseUtil.getPut("3","content",null,"Hadoop by reading the documentation");
Put put4 = HBaseUtil.getPut("4","content",null,"Hadoop from the release page");
Put put5 = HBaseUtil.getPut("5","content",null,"Hadoop on the mailing list");
puts.add(put1);
puts.add(put2);
puts.add(put3);
puts.add(put4);
puts.add(put5);
//提交测试数据
htable.put(puts);
htable.flushCommits();
htable.close();
//创建stat表，只有一个列祖result
HBaseUtil.createTable("stat","result");
}
}
4.hbase工具类，里面涉及到java对hbase数据库创建表，删除表，常见的crud操作等等。具体参照代码：
package com.oracle.hbase.weifenbushi;
import java.io.IOException;
import java.util.Arrays;
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.MasterNotRunningException;
import org.apache.hadoop.hbase.ZooKeeperConnectionException;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HBaseAdmin;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.filter.CompareFilter.CompareOp;
import org.apache.hadoop.hbase.filter.Filter;
import org.apache.hadoop.hbase.filter.FilterList;
import org.apache.hadoop.hbase.filter.FilterList.Operator;
import org.apache.hadoop.hbase.filter.SingleColumnValueFilter;
import org.apache.hadoop.hbase.util.Bytes;
public class HBaseUtil {
/**
* 初始化HBase的配置文件
* @return
*/
public static Configuration getConfiguration(){
Configuration conf = HBaseConfiguration.create();
//和hbase-site.xml中配置的一致
conf.set("hbase.zooker.quorum", "192.168.10.127");
// conf.set("hbase.zooker.quorum", "oraclehadoop1");
return conf;
}
/**
* 实例化HBaseAdmin,HBaseAdmin用于对表的元素据进行操作
* @return
* @throws MasterNotRunningException
* @throws ZooKeeperConnectionException
*/
public static HBaseAdmin getHBaseAdmin() throws MasterNotRunningException, ZooKeeperConnectionException{
HBaseAdmin a=null;
try {
a= new HBaseAdmin(getConfiguration());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return a;
}
/**
* 创建表
* @param tableName 表名
* @param columnFamilies 列族
* @throws IOException
*/
public static void createTable(String tableName,String...columnFamilies) throws IOException {
HTableDescriptor htd = new HTableDescriptor(tableName.getBytes());//
for(String fc : columnFamilies) {
htd.addFamily(new HColumnDescriptor(fc));
}
getHBaseAdmin().createTable(htd);
}
/**
* 获取HTableDescriptor
* @param tableName
* @return
* @throws IOException
*/
public static HTableDescriptor getHTableDescriptor(byte[] tableName) throws IOException{
return getHBaseAdmin().getTableDescriptor(tableName);
}
/**
* 获取表
* @param tableName 表名
* @return
* @throws IOException
*/
public static HTable getHTable(String tableName) throws IOException{
return new HTable(getConfiguration(),tableName);
}
/**
* 获取Put,Put是插入一行数据的封装格式
* @param tableName
* @param row
* @param columnFamily
* @param qualifier
* @param value
* @return
* @throws IOException
*/
public static Put getPut(String row,String columnFamily,String qualifier,String value) throws IOException{
Put put = new Put(row.getBytes());
if(qualifier==null||"".equals(qualifier)) {
put.add(columnFamily.getBytes(), null, value.getBytes());
}else {
put.add(columnFamily.getBytes(), qualifier.getBytes(), value.getBytes());
}
return put;
}
/**
* 查询某一行的数据
* @param tableName 表名
* @param row 行键
* @return
* @throws IOException
*/
public static Result getResult(String tableName,String row) throws IOException {
Get get = new Get(row.getBytes());
HTable htable = getHTable(tableName);
Result result = htable.get(get);
htable.close();
return result;
}
/**
* 条件查询
* @param tableName 表名
* @param columnFamily 列族
* @param queryCondition 查询条件值
* @param begin 查询的起始行
* @param end 查询的终止行
* @return
* @throws IOException
*/
public static ResultScanner getResultScanner(String tableName,String columnFamily,String queryCondition,String begin,String end) throws IOException{
Scan scan = new Scan();
//设置起始行
scan.setStartRow(Bytes.toBytes(begin));
//设置终止行
scan.setStopRow(Bytes.toBytes(end));
//指定要查询的列族
scan.addColumn(Bytes.toBytes(columnFamily),null);
//查询列族中值等于queryCondition的记录
Filter filter1 = new SingleColumnValueFilter(Bytes.toBytes(columnFamily),null,CompareOp.EQUAL,Bytes.toBytes(queryCondition));
//Filter filter2 = new SingleColumnValueFilter(Bytes.toBytes(columnFamily),null,CompareOp.EQUAL,Bytes.toBytes("chuliuxiang"));
FilterList filterList = new FilterList(Operator.MUST_PASS_ONE,Arrays.asList(filter1));
scan.setFilter(filterList);
HTable htable = getHTable(tableName);
ResultScanner rs = htable.getScanner(scan);
htable.close();
return rs;
}
public static void main(String[] args) {
try {
Result result = getResult("word", "1");
System.out.println(new String(result.list().get(0).getValue()));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
总结：
以上就是java对hbase伪分布式的访问，对集群的访问也是一样，api是不会变的，变化的是配置文件，对应的quorum是zookeeper集群，配置变为： conf.set("hbase.zookeeper.quorum", "weekend05:2181,weekend06:2181,weekend07:2181");
ok，希望对大家会有帮助。