Hbase Java 实例

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