HBase的JavaAPI操作

如果是DDL的操作就找HbaseAdmin.

如果是表上的增删改查的操作就找HTable.

附录代码:

mport 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.KeyValue;
import org.apache.hadoop.hbase.TableName;
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.filter.CompareFilter.CompareOp;
import org.apache.hadoop.hbase.filter.Filter;
import org.apache.hadoop.hbase.filter.SingleColumnValueFilter;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class HBaseCRUDTest {
    
    private HBaseAdmin hBaseAdmin;
    private Configuration conf;
    
    /**
     * 对必须用的对象放在@Before中进行初始化
     * @throws Exception
     */
    @Before
    public void setUp() throws Exception{
        /*创建conf对象的第一种方式
        conf = new Configuration();
        conf.set("hbase.rootdir", "hdfs://crxy99:9000/hbase");
        conf.set("hbase.cluster.distributed", "true");
        conf.set("hbase.zookeeper.quorum", "crxy99");
        */
        //创建对象的第二种方式
        //这种方式需要再Maven的src/test/resoures目录中放置Hbase集群上的hbase-site.xml文件.
        conf = HBaseConfiguration.create();
        
        hBaseAdmin = new HBaseAdmin(conf);//通过Configuration对象得到HBaseAdmin对象.
        System.out.println("-------setUp-------");
        
    }
    
    
    /**
     * 是用完HBaseAdmin对象之后需要关闭.
     * @throws Exception
     */
    @After
    public void cleanUp() throws Exception {
        hBaseAdmin.close();
        System.out.println("-------cleanUp-----");
    }
    
    
    /**
     * 打印出Hbase中所有的表.
     * @throws Exception
     */
    @Test
    @SuppressWarnings("deprecation")
    public void testListTables() throws Exception{
        System.out.println("------listTables------");
        //获得Hbase中表的方法一:
        String [] tableNames = hBaseAdmin.getTableNames();
        System.out.println(Arrays.toString(tableNames));
        
        //获得Hbase中表的方法二:
        TableName[] listTables= hBaseAdmin.listTableNames();
        System.out.println(Arrays.toString(listTables));
        
        //获得Hbase中表的方法三(用到了HTableDescriptor对象):
        HTableDescriptor[] listTabels2 = hBaseAdmin.listTables();
        for (HTableDescriptor hTD : listTabels2) {
            System.out.print(hTD.getTableName() + " ");
        }
        System.out.println();
    }
    
    /**
     * 向HBase中增加一个表
     */
    @Test
    public void testAddTable() throws Exception {
        System.out.println("-----addTable-----");
        HTableDescriptor desc = new HTableDescriptor("t2");//创建表的名称
        HColumnDescriptor family = new HColumnDescriptor("cf"); //创建表的列族
        desc.addFamily(family);//向表中添加列族 (Hbase在创建表的时候就要添加列族.)
        /*
         *HBase对单行做到了一个事务,hbase不支持跨行的事务 
         */
        
        //table.checkAndPut(row, family, qualifier, value, put)
        
        hBaseAdmin.createTable(desc);
    }
    
    /**
     * 向表中插入数据
     * 操作表中的数据就是需要操作表本身,需要用到了HTable对象.
     */
    @Test
    public void testAddRecord() throws Exception {
        HTable table = new HTable(conf, "t2");//操作上面新建的t2
        String rowKey = "1";
        String family = "cf";
        //String qualifier = "name";
        String qualifier = "age";
        //String value = "SummerChill";
        String value = "18";
        Put put = new Put(rowKey.getBytes());//put对象传入的是一个"行键rowkey"
        //HBase中存储的都是字节数组  
        //插入表中数据的时候hbase的shell操作用的put命令,JavaAPI对应的是Put对象.
        put.add(family.getBytes(), qualifier.getBytes(), value.getBytes());
        table.put(put);
        table.close();
        System.out.println("------addRecord-------");
    }
    
    /**
     * 查询表中的数据
     */
    @SuppressWarnings("deprecation")
    @Test
    public void testQueryRecord() throws Exception {
        HTable table = new HTable(conf, "t2");
        String rowKey = "1";
        //查询表中数据的时候HBase的shell操作用的get命令,JavaAPI对应的是Get对象.
        Get get = new Get(rowKey.getBytes());
        get.addColumn("cf".getBytes(), "age".getBytes());
        Result result = table.get(get);
        KeyValue[] keyVs =  result.raw();
        for(KeyValue kv : keyVs ){
            byte[] qualifier = kv.getQualifier();
            byte[] value = kv.getValue();
            System.out.println(new String(qualifier) + "=" + new String(value));
        }
        table.close();
        System.out.println("-----getRecord-----");
    }
    
    /**
     * 条件查询 
     */
    @SuppressWarnings("deprecation")
    @Test
    public void testQueryByCondition() throws Exception {
        HTable table = new HTable(conf, "t2");
        Scan scan = new Scan();
        Filter filter = new SingleColumnValueFilter(
                "cf".getBytes(),"age".getBytes(),
                CompareOp.GREATER, "13".getBytes());
        //CompareOp是一个操作的枚举常量
        scan.setFilter(filter);
        ResultScanner rs = table.getScanner(scan);
        
        for (Result result : rs) {
            KeyValue[] keyVs = result.raw();
            for (KeyValue kv : keyVs) {
                byte[] qualifier = kv.getQualifier();
                byte[] value = kv.getValue();
                System.out.print(new String(qualifier) + "=" + new String(value) + " ");
            }
            System.out.println();
        }
        table.close();
        System.out.println("-----getRecord-----");
    }
    
    /**
     * 删除表中的记录
     */
    @Test
    public void testDeleteRecored() throws Exception {
        HTable table = new HTable(conf, "t2");
        byte[] row = "2".getBytes();
        Delete delete = new Delete(row);
        //删除指定的rowkey对应的某一列
        //delete.deleteColumn("cf".getBytes(), "age".getBytes());
        table.delete(delete);
        table.close();
        System.out.println("-----deleteRecord-----");
    }
    
    /**
     * 删除表
     */
    @Test
    public void testDropTable() throws Exception {
        //删除表之前对表是否存在进行判断.
        if(!hBaseAdmin.tableExists("t2")) {
            throw new RuntimeException("Table Not Exists,你想弄啥嘞！");
        }
        if(hBaseAdmin.isTableEnabled("t2")) {
            hBaseAdmin.disableTable("t2");
        }
        //在删除表之前必须对表设置disable,否则直接删除 会抛出异常
        hBaseAdmin.deleteTable("t2");
        System.out.println("-----deleteTable-----");
    }

}