Hbase Java 实例

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发现一HBase实例文章：http://archive.cnblogs.com/a/2178069/

HBase提供了java api来对HBase进行一系列的管理涉及到对表的管理、数据的操作等。常用的API操作有：

1. 对表的创建、删除、显示以及修改等，可以用HBaseAdmin，一旦创建了表，那么可以通过HTable的实例来访问表，每次可以往表里增加数据。

2. 插入数据

创建一个Put对象，在这个Put对象里可以指定要给哪个列增加数据，以及当前的时间戳等值，然后通过调用HTable.put(Put)来提交操作，子猴在这里提请注意的是：在创建Put对象的时候，你必须指定一个行(Row)值，在构造Put对象的时候作为参数传入。

3. 获取数据

要获取数据，使用Get对象，Get对象同Put对象一样有好几个构造函数，通常在构造的时候传入行值，表示取第几行的数据，通过HTable.get(Get)来调用。

4. 浏览每一行

通过Scan可以对表中的行进行浏览，得到每一行的信息，比如列名，时间戳等，Scan相当于一个游标，通过next()来浏览下一个，通过调用HTable.getScanner(Scan)来返回一个ResultScanner对象。HTable.get(Get)和HTable.getScanner(Scan)都是返回一个Result。Result是一个

KeyValue的链表。

5. 删除

使用Delete来删除记录，通过调用HTable.delete(Delete)来执行删除操作。（注：删除这里有些特别，也就是删除并不是马上将数据从表中删除。）

6. 锁

新增、获取、删除在操作过程中会对所操作的行加一个锁，而浏览却不会。

7. 簇的访问

客户端代码通过ZooKeeper来访问找到簇，也就是说ZooKeeper quorum将被使用，那么相关的类（包）应该在客户端的类（classes）目录下，即客户端一定要找到文件hbase-site.xml。

以下是一个完整的代码示例，基于hbase-0.90.3编写:

import java.io.IOException;import java.util.ArrayList;import java.util.List; 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.KeyValue;import org.apache.hadoop.hbase.MasterNotRunningException;import org.apache.hadoop.hbase.ZooKeeperConnectionException;import org.apache.hadoop.hbase.client.Delete;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.Result;import org.apache.hadoop.hbase.client.ResultScanner;import org.apache.hadoop.hbase.client.Scan;import org.apache.hadoop.hbase.client.Put;import org.apache.hadoop.hbase.util.Bytes; public class HBaseTest {        private static Configuration conf = null;         /**     * 初始化配置     */    static {        Configuration HBASE_CONFIG = new Configuration();        //与hbase/conf/hbase-site.xml中hbase.zookeeper.quorum配置的值相同         HBASE_CONFIG.set("hbase.zookeeper.quorum", "10.1.1.1");        //与hbase/conf/hbase-site.xml中hbase.zookeeper.property.clientPort配置的值相同        HBASE_CONFIG.set("hbase.zookeeper.property.clientPort", "2181");        conf = HBaseConfiguration.create(HBASE_CONFIG);    }        /**     * 创建一张表     */    public static void creatTable(String tableName, String[] familys) throws Exception {        HBaseAdmin admin = new HBaseAdmin(conf);        if (admin.tableExists(tableName)) {            System.out.println("table already exists!");        } else {            HTableDescriptor tableDesc = new HTableDescriptor(tableName);            for(int i=0; i<familys.length; i++){                tableDesc.addFamily(new HColumnDescriptor(familys[i]));            }            admin.createTable(tableDesc);            System.out.println("create table " + tableName + " ok.");        }     }        /**     * 删除表     */    public static void deleteTable(String tableName) throws Exception {       try {           HBaseAdmin admin = new HBaseAdmin(conf);           admin.disableTable(tableName);           admin.deleteTable(tableName);           System.out.println("delete table " + tableName + " ok.");       } catch (MasterNotRunningException e) {           e.printStackTrace();       } catch (ZooKeeperConnectionException e) {           e.printStackTrace();       }    }         /**     * 插入一行记录     */    public static void addRecord (String tableName, String rowKey, String family, String qualifier, String value)            throws Exception{        try {            HTable table = new HTable(conf, tableName);            Put put = new Put(Bytes.toBytes(rowKey));            put.add(Bytes.toBytes(family),Bytes.toBytes(qualifier),Bytes.toBytes(value));            table.put(put);            System.out.println("insert recored " + rowKey + " to table " + tableName +" ok.");        } catch (IOException e) {            e.printStackTrace();        }    }     /**     * 删除一行记录     */    public static void delRecord (String tableName, String rowKey) throws IOException{        HTable table = new HTable(conf, tableName);        List list = new ArrayList();        Delete del = new Delete(rowKey.getBytes());        list.add(del);        table.delete(list);        System.out.println("del recored " + rowKey + " ok.");    }         /**     * 查找一行记录     */    public static void getOneRecord (String tableName, String rowKey) throws IOException{        HTable table = new HTable(conf, tableName);        Get get = new Get(rowKey.getBytes());        Result rs = table.get(get);        for(KeyValue kv : rs.raw()){            System.out.print(new String(kv.getRow()) + " " );            System.out.print(new String(kv.getFamily()) + ":" );            System.out.print(new String(kv.getQualifier()) + " " );            System.out.print(kv.getTimestamp() + " " );            System.out.println(new String(kv.getValue()));        }    }         /**     * 显示所有数据     */    public static void getAllRecord (String tableName) {        try{             HTable table = new HTable(conf, tableName);             Scan s = new Scan();             ResultScanner ss = table.getScanner(s);             for(Result r:ss){                 for(KeyValue kv : r.raw()){                    System.out.print(new String(kv.getRow()) + " ");                    System.out.print(new String(kv.getFamily()) + ":");                    System.out.print(new String(kv.getQualifier()) + " ");                    System.out.print(kv.getTimestamp() + " ");                    System.out.println(new String(kv.getValue()));                 }             }        } catch (IOException e){            e.printStackTrace();        }    }        public static void  main (String [] agrs) {        try {            String tablename = "scores";            String[] familys = {"grade", "course"};            HBaseTest.creatTable(tablename, familys);                         //add record zkb            HBaseTest.addRecord(tablename,"zkb","grade","","5");            HBaseTest.addRecord(tablename,"zkb","course","","90");            HBaseTest.addRecord(tablename,"zkb","course","math","97");            HBaseTest.addRecord(tablename,"zkb","course","art","87");            //add record  baoniu            HBaseTest.addRecord(tablename,"baoniu","grade","","4");            HBaseTest.addRecord(tablename,"baoniu","course","math","89");                         System.out.println("===========get one record========");            HBaseTest.getOneRecord(tablename, "zkb");                         System.out.println("===========show all record========");            HBaseTest.getAllRecord(tablename);                         System.out.println("===========del one record========");            HBaseTest.delRecord(tablename, "baoniu");            HBaseTest.getAllRecord(tablename);                         System.out.println("===========show all record========");            HBaseTest.getAllRecord(tablename);        } catch (Exception e) {            e.printStackTrace();        }    }}

程序编译为一个jar包hbtest.jar

source ~/.bash_profile

export HADOOP_CLASSPATH=/home/admin/hadoop/hadoop-core-0.20.2-CDH3B4.jar:/home/admin/hbase/hbase-0.90.3.jar:/home/admin/zookeeper/zookeeper-3.3.2.jar

hadoop jar hbtest.jar