HBase 基本Java API

最新推荐文章于 2020-12-21 10:44:49 发布

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本文介绍HBase数据库的基本组件，包括配置、管理、表操作、数据读写等方面，并通过示例展示了如何使用Java API进行表的增删查改操作。

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数据库：HBaseConfiguration HBaseAdmin

表：HTable HTableDescriptor

列族：HColumnDescriptor

行列操作：Put Get Scanner

HBaseConfiguration:

Configuration create()

//从classpath中查找hbase-site.xml初始化Configuration，如果没有，默认读取HBase-版本号.jar中的默认配置文件

void merger(Configuration destConf, Configuration srcConf) //合并两个Configuration

用法：Configuration config = HBaseConfiguration.create();

HBaseAdmin:

管理HBase数据库信息，可以创建表、删除表、列出表项、使表有效或无效、添加删除列族

void addColumn (String tableName, HColumnDescriptor column) //添加列族

void checkHBaseAvailable (HBaseConfiguration conf) //查看HBase状态，静态函数

void createTable (HTableDescriptor desc) //创建一个新表，同步操作

void deleteTable (byte[] tableName) //删除表

void enableTable (byte[] tableName) //使表有效

void disableTable (byte[] tableName) //使表无效

HTableDescriptor[] listTable() //列出所有用户空间表项

void modifyTable (byte[] tableName, HTableDescriptor htd) //修改表模式，异步操作，耗时

boolean tableExists (String tableName); //检查表是否存在

用法：HBaseAdmin admin = new HBaseAdmin(config); admin.disableTable(Bytes.toBytes("tablename"));

HTableDescriptor:

包含了表的名字及列族

void addFamily (HColumnDescriptor cdesc) //添加一个列族

HColumnDescriptor removeFamily ( byte[] column) //移除一个列族

byte[] getName () //获取表名

byte[] getValue (byte[] key) //获取属性值

void setValue (String key, String value ) //设置属性值

用法：

HTableDescriptor htd = new HTableDescriptor ("tableName");

htd.addFamily (new HColumnDescriptor("Family"));

HColumnDescriptor:

维护列族信息，如版本号、压缩设置等，通常在创建表或添加列族时使用

列族被创建后不能直接修改，只能删除后重建

列族被删除后，对应数据一同被删除

byte[] getName() //获取列族名字

byte[] getValue() //获取对应属性值

void setValue (String key, String value) //设置对应属性值

HTable:

用来与HBase表进行通信，非线程安全，若有多个线程，使用HTablePool

void checkAndPut (byte[] row, byte[] family, byte[] quaalifier, byte[] value, Put put) //自动检查row/family/qualifier/是否与给定的值匹配

void close() //释放资源

boolean exists (Get get) //检查get锁指定的值是否存在

Result get(Get get) //取出指定行的某些单元格对应的值

byte[][] getEndKeys () //获取表每个Region的结束键值

ResultScanner getScanner (byte[] family) //获取给定列族的Scanner实例

HTableDescriptor getTableDescriptor() //获取当前表的HTableDescriptor实例

byte[] getTableName() //获取表名

void put (Put put) //向表中添加值

用法：

HTable table = new HTable (conf, Bytes.toBytes("tablename"));

ResultScanner scanner = table.getScanner (Bytes.toBytes("cf"));

Put:

添加数据

Put add (byte[] family, byte[] quaalifier, byte[] value)

Put add (byte[] family, byte[] quaalifier, long ts, byte[] value)

List<Key Value> get (byte[] family, byte[] qualifier) //返回与指定列族:列匹配的项

boolean has (byte[] family, byte[] qualifier) //检查是否有列族:列

用法：

HTable table = new HTable(conf, Bytes.toBytes("tablename"));

Put p = new Put(Bytes.toBytes("row")); //为指定行建一个Put操作

p.add(Bytes.toBytes("family"), Bytes.toBytes("qulifier"), Bytes.toBytes("tvalue"));

table.put(p);

Get:

获取单行信息

Get addColumn (byte[] family, byte[] qualifier)

Get addFamily (byte[] family)

Get setTimeRange (long minStamp, long maxStamp)

Get setFilter (Filter filter)

用法：

HTable table = new HTable(conf, Bytes.toBytes("tablename"));

Get g = new Get(Bytes.toBytes("row")); //为指定行建一个Get操作

Result result = table.get(g);

Result:

存储Get或Scan操作后获取的表的单行值

boolean containsColumn (byte[] family, byte[] qualifier)

NavigableMap<byte[], byte[]> getFamilyMap (byte[] family) //返回列族的qulifier:value们

byte[] getValue (byte[] family, byte[] qualifier)

ResultScanner:

void close()

Result next()

用法：

ResultScanner scanner = table.getScanner (Bytes.toBytes(family));

for ( Result rowResult : scanner )

byte[] str = rowResult.getValue ( Bytes.toBytes("family"), Bytes.toBytes("column") )

import java.util.List;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Cell;
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.BinaryComparator;
import org.apache.hadoop.hbase.filter.BinaryPrefixComparator;
import org.apache.hadoop.hbase.filter.ByteArrayComparable;
import org.apache.hadoop.hbase.filter.ColumnPrefixFilter;
import org.apache.hadoop.hbase.filter.CompareFilter.CompareOp;
import org.apache.hadoop.hbase.filter.FamilyFilter;
import org.apache.hadoop.hbase.filter.Filter;
import org.apache.hadoop.hbase.filter.MultipleColumnPrefixFilter;
import org.apache.hadoop.hbase.filter.PrefixFilter;
import org.apache.hadoop.hbase.filter.QualifierFilter;
import org.apache.hadoop.hbase.filter.RegexStringComparator;
import org.apache.hadoop.hbase.filter.RowFilter;
import org.apache.hadoop.hbase.filter.SingleColumnValueFilter;
import org.apache.hadoop.hbase.filter.SubstringComparator;
import org.apache.hadoop.hbase.master.TableNamespaceManager;
import org.apache.hadoop.hbase.util.Bytes;
import org.junit.Before;
import org.junit.Test;

public class HbaseDemo {

	private Configuration conf = null;
	
	@Before
	public void init(){
		conf = HBaseConfiguration.create();
		conf.set("hbase.zookeeper.quorum", "hdp0,hdp1,hdp2");
	}
	
	@Test
	public void testDrop() throws Exception{
		HBaseAdmin admin = new HBaseAdmin(conf);
		admin.disableTable("account");
		admin.deleteTable("account");
		admin.close();
	}
	
	@Test
	public void testPut() throws Exception{
		HTable table = new HTable(conf, "person_info");
		Put p = new Put(Bytes.toBytes("person_rk_bj_zhang_000002"));
		p.add("base_info".getBytes(), "name".getBytes(), "zhangwuji".getBytes());
		table.put(p);
		table.close();
	}
	
	@Test
	public void testGet() throws Exception{
		HTable table = new HTable(conf, "person_info");
		Get get = new Get(Bytes.toBytes("person_rk_bj_zhang_000001"));
		get.setMaxVersions(5);
		Result result = table.get(get);
		List<Cell> cells = result.listCells();
		
//		result.getValue(family, qualifier);  可以从result中直接取出一个特定的value
		
		//遍历出result中所有的键值对
		for(KeyValue kv : result.list()){
			String family = new String(kv.getFamily());
			System.out.println(family);
			String qualifier = new String(kv.getQualifier());
			System.out.println(qualifier);
			System.out.println(new String(kv.getValue()));
			
		}
		table.close();
	}
	
	/**
	 * 多种过滤条件的使用方法
	 * @throws Exception
	 */
	@Test
	public void testScan() throws Exception{
		HTable table = new HTable(conf, "person_info".getBytes());
		Scan scan = new Scan(Bytes.toBytes("person_rk_bj_zhang_000001"), Bytes.toBytes("person_rk_bj_zhang_000002"));
		
		//前缀过滤器----针对行键
		Filter filter = new PrefixFilter(Bytes.toBytes("rk"));
		
		//行过滤器
		ByteArrayComparable rowComparator = new BinaryComparator(Bytes.toBytes("person_rk_bj_zhang_000001"));
		RowFilter rf = new RowFilter(CompareOp.LESS_OR_EQUAL, rowComparator);
		
		/**
                * 假设rowkey格式为：创建日期_发布日期_ID_TITLE
                * 目标：查找  发布日期  为  2014-12-21  的数据
                 */
                rf = new RowFilter(CompareOp.EQUAL , new SubstringComparator("_2014-12-21_"));
		
		
		//单值过滤器 1 完整匹配字节数组
		new SingleColumnValueFilter("base_info".getBytes(), "name".getBytes(), CompareOp.EQUAL, "zhangsan".getBytes());
		//单值过滤器2 匹配正则表达式
		ByteArrayComparable comparator = new RegexStringComparator("zhang.");
		new SingleColumnValueFilter("info".getBytes(), "NAME".getBytes(), CompareOp.EQUAL, comparator);

		//单值过滤器2 匹配是否包含子串,大小写不敏感
		comparator = new SubstringComparator("wu");
		new SingleColumnValueFilter("info".getBytes(), "NAME".getBytes(), CompareOp.EQUAL, comparator);

		//键值对元数据过滤-----family过滤----字节数组完整匹配
                FamilyFilter ff = new FamilyFilter(
                CompareOp.EQUAL , 
                new BinaryComparator(Bytes.toBytes("base_info"))   //表中不存在inf列族，过滤结果为空
                );
                //键值对元数据过滤-----family过滤----字节数组前缀匹配
                ff = new FamilyFilter(
                CompareOp.EQUAL , 
                new BinaryPrefixComparator(Bytes.toBytes("inf"))   //表中存在以inf打头的列族info，过滤结果为该列族所有行
                );
		
        
               //键值对元数据过滤-----qualifier过滤----字节数组完整匹配
        
                filter = new QualifierFilter(
                CompareOp.EQUAL , 
                new BinaryComparator(Bytes.toBytes("na"))   //表中不存在na列，过滤结果为空
                );
                filter = new QualifierFilter(
                CompareOp.EQUAL , 
                new BinaryPrefixComparator(Bytes.toBytes("na"))   //表中存在以na打头的列name，过滤结果为所有行的该列数据
        		);
		
               //基于列名(即Qualifier)前缀过滤数据的ColumnPrefixFilter
               filter = new ColumnPrefixFilter("na".getBytes());
        
               //基于列名(即Qualifier)多个前缀过滤数据的MultipleColumnPrefixFilter
               byte[][] prefixes = new byte[][] {Bytes.toBytes("na"), Bytes.toBytes("me")};
               filter = new MultipleColumnPrefixFilter(prefixes);
 
               //为查询设置过滤条件
               scan.setFilter(filter);
        
        
		scan.addFamily(Bytes.toBytes("base_info"));
		ResultScanner scanner = table.getScanner(scan);
		for(Result r : scanner){
			/**
			for(KeyValue kv : r.list()){
				String family = new String(kv.getFamily());
				System.out.println(family);
				String qualifier = new String(kv.getQualifier());
				System.out.println(qualifier);
				System.out.println(new String(kv.getValue()));
			}
			*/
			//直接从result中取到某个特定的value
			byte[] value = r.getValue(Bytes.toBytes("base_info"), Bytes.toBytes("name"));
			System.out.println(new String(value));
		}
		table.close();
	}
	
	
	@Test
	public void testDel() throws Exception{
		HTable table = new HTable(conf, "user");
		Delete del = new Delete(Bytes.toBytes("rk0001"));
		del.deleteColumn(Bytes.toBytes("data"), Bytes.toBytes("pic"));
		table.delete(del);
		table.close();
	}
	

	
	public static void main(String[] args) throws Exception {
		Configuration conf = HBaseConfiguration.create();
		conf.set("hbase.zookeeper.quorum", "hdp0:2181,hdp1:2181,hdp2:2181");
		HBaseAdmin admin = new HBaseAdmin(conf);
		
		TableName tableName = TableName.valueOf("person_info");
		HTableDescriptor td = new HTableDescriptor(tableName);
		HColumnDescriptor cd = new HColumnDescriptor("base_info");
		cd.setMaxVersions(10);
		td.addFamily(cd);
		admin.createTable(td);
		
		admin.close();

	}
	
	

}