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;    }

hbase-site.xml，注意里面主机名要跟core-site.xml一致，另外还需要在hosts文件加一行主机名和hbase服务器ip地址的映射。（windows下面的hosts文件在：C:\Windows\System32\drivers\etc）

具体文件hbase-site.xml参照内容如下：

<configuration><property>  <name>hbase.rootdir</name>    <value>hdfs://chidianwei-VirtualBox:9000/hbase</value>    </property>    <property>      <name>hbase.cluster.distributed</name>        <value>true</value>        </property>        <property>          <name>hbase.zookeeper.quorum</name>            <value>chidianwei-VirtualBox</value>            </property>            <property>              <name>dfs.replication</name>                <value>1</value>                </property></configuration>

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<Put> puts = new ArrayList<Put>();              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 blocke.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 blocke.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。