Java操作HBase

import java.io.IOException;
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.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.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.util.Bytes;

public class TestHBaseJava {
    
    private static Configuration conf = null;
    /**
     * 初始化配置
     */
    static {
        conf = HBaseConfiguration.create();
        conf.addResource("hbase-site.xml"); //this is default,so don't have to write this here
    }
    
    public static void main(String[] args) throws IOException {
        System.out.println("HelloWorld");
        String[] cfs = new String[1];
        cfs[0] = "data";
        createTable("Test",cfs);
        writeRow("Test",cfs);
    }

    /**
     * 创建表操作
     * @throws IOException
     */
    public static void createTable(String tableName, String[] cfs) throws IOException{
        HBaseAdmin admin = new HBaseAdmin(conf);
        
        if(admin.tableExists(tableName)){
            System.out.println("this table is already exist!");
        } else {
            HTableDescriptor htd = new HTableDescriptor(tableName);
            for(int i=0; i<cfs.length;i++){
                htd.addFamily(new HColumnDescriptor(cfs[i]));
            }
            admin.createTable(htd);
            System.out.println("create table successfully");
        }
    }
    /**
     * 删除表操作
     * @param tablename
     * @throws IOException
     */
    public static void deleteTable(String tableName) throws IOException{
            HBaseAdmin admin = new HBaseAdmin(conf);
            admin.disableTable(tableName);
            admin.deleteTable(tableName);
            System.out.println("delete table successfully");     
    }
    /**
     * 插入一行记录
     * @param tablename
     * @param cfs
     */
    public static void writeRow(String tableName,String[] cfs) throws IOException{
        HTable table = new HTable(conf,tableName);
        Put put = new Put(Bytes.toBytes("rows1"));
        for(int i=0; i<cfs.length;i++){
            put.add(Bytes.toBytes(cfs[i]),Bytes.toBytes("1"),Bytes.toBytes("value_1"));
            table.put(put);
        }
    }
    /**
     * 删除一行记录
     * @param tablename
     * @param rowkey
     * @throws IOException
     */
    public static void deleteRow(String tableName, String rowKey) throws IOException {
        HTable table = new HTable(conf, tableName);
        Delete d1 = new Delete(rowKey.getBytes());
        table.delete(d1);
        System.out.println("删除行成功！");
    }
    /**
     * 查找一行记录
     * @param tablename
     * @param rowkey
     */
    public static void selectRow(String tableName, String rowKey) throws IOException {
        HTable table = new HTable(conf, tableName);
        Get g = new Get(rowKey.getBytes());
        Result rs = table.get(g);
        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()));
        }
    }
    /**
     * 查询表中所有行
     * @param tablename
     */
    public static void scaner(String tableName) throws IOException {
            HTable table = new HTable(conf, tableName);
            Scan s = new Scan();
            ResultScanner rs = table.getScanner(s);
            for (Result r : rs) {
                KeyValue[] kv = r.raw();
                for (int i = 0; i < kv.length; i++) {
                    System.out.print(new String(kv[i].getRow()) + "  ");
                    System.out.print(new String(kv[i].getFamily()) + ":");
                    System.out.print(new String(kv[i].getQualifier()) + "  ");
                    System.out.print(kv[i].getTimestamp() + "  ");
                    System.out.println(new String(kv[i].getValue()));
                    }
                }
       
    }
    
}

说明：

我们用org.apache.hadoop.hbase.HBase.Configurationn创建一个实例org.apache.hadoop.conf.Configuration

这个Configuration会返回一个读入classpath下的hbase-site.xml 和 hbase-default.xml中HBase配置信息的Configuration；

此Configuration还将用于创建HBaseAdmin和HTable(在org.apache.hadoop.hbase.client包中)

HBaseAdmin 用于管理HBase集群，create,drop,list,enable and disable tables. add and drop table column families.

HTable 用于访问指定的表；add, update, and delete data from an individual table.

Configuration实例指向了集群上（执行这些代码的集群）的这些类；

要创建一个表，需要创建一个HBaseAdmin实例，让它来创建表；

我们用org.apache.hadoop.hbase.HTableDescriptor和org.apache.hadoop.hbase.HColumnDescriptor来修改表的模式；

要对表操作，需创建HTable实例。

Result是一个row对应的所有或部分cell,一个row对应一个Result;

KeyValue对应一个cell;

ResultScanner是Result的集合。