业务开发测试HBase之旅三：通过Java Api与HBase交互
2011年10月11日 由
引言
HBase提供了Java Api的访问接口，掌握这个就跟Java应用使用RDBMS时需要JDBC一样重要，本文将继续前两篇文章中blog表的示例，介绍常用的Api。练习前的准备工作创建一个Maven工程，加入以下依赖：如果你的Maven库里还没有hbase，还需要配置下repository
<dependency> <groupId>org.apache.hbase</groupId> <artifactId>hbase</artifactId> <version>0.90.2</version> </dependency><repositories> <repository> <id>cloudera</id> <url>https://repository.cloudera.com/content/groups/public</url> </repository> </repositories>确保HBase环境已启动且能连接到，将HBase环境的hbase-site.xml文件拷贝到上述工程的src/test/resources目录加载配置
Configuration conf = new Configuration(); // conf.addResource("hbase-site-cluster.xml");//可以指定文件加载 conf = HBaseConfiguration.create(conf);创建表/**========创建表=========*/ HTableDescriptor desc = new HTableDescriptor("blog"); desc.addFamily(new HColumnDescriptor("article")); desc.addFamily(new HColumnDescriptor("author")); admin.createTable(desc );增加记录/**=========插入数据=========*/ Put put = new Put(Bytes.toBytes("1")); put.add(Bytes.toBytes("article"), Bytes.toBytes("title"), Bytes.toBytes("Head First HBase")); put.add(Bytes.toBytes("article"), Bytes.toBytes("content"), Bytes.toBytes("HBase is the Hadoop database. Use it when you need random, realtime read/write access to your Big Data.")); put.add(Bytes.toBytes("article"), Bytes.toBytes("tags"), Bytes.toBytes("Hadoop,HBase,NoSQL")); put.add(Bytes.toBytes("author"), Bytes.toBytes("name"), Bytes.toBytes("hujinjun")); put.add(Bytes.toBytes("author"), Bytes.toBytes("nickname"), Bytes.toBytes("一叶渡江")); table.put(put);知识点回顾：RowKey 和 ColumnName 是二进制值（Java 类型 byte[]），value 是一个字节数组（Java类型 byte[]）根据RowKey查询/**=========根据rowkey Get get = new Get(Bytes.toBytes("1")); 查询数据=========*/ Result result = table.get(get); for(KeyValue kv :result.list()){ System.out.println("family:" +Bytes.toString(kv.getFamily())); System.out.println("qualifier:" +Bytes.toString(kv.getQualifier())); System.out.println("value:" +Bytes.toString(kv.getValue())); System.out.println("Timestamp:" +kv.getTimestamp()); }遍历查询与迭代/**=========遍历查询=========*/ Scan scan = new Scan(); ResultScanner rs =null; try { rs = table.getScanner(scan); for (Result r : rs) { for(KeyValue kv :r.list()){ System.out.println("family:" +Bytes.toString(kv.getFamily())); System.out.println("qualifier:" +Bytes.toString(kv.getQualifier())); System.out.println("value:" +Bytes.toString(kv.getValue())); } } } finally { rs.close(); }知识点回顾：
可以看到上面代码我们用了两次for循环来遍历迭代。
更新练习 /**=========更新=========*///查询更新前的值 Get get2 = new Get(Bytes.toBytes("1")); get2.addColumn(Bytes.toBytes("author"), Bytes.toBytes("nickname")); assertThat(Bytes.toString(table.get(get2).list().get(0).getValue()),is("一叶渡江")); //更新nickname为yedu Put put2 = new Put(Bytes.toBytes("1")); : put2.add(Bytes.toBytes("author"), Bytes.toBytes("nickname"), Bytes.toBytes("yedu")); table.put(put2); //查询更新结果 Get get3 = new Get(Bytes.toBytes("1")); get3.addColumn(Bytes.toBytes("author"), Bytes.toBytes("nickname")); assertThat(Bytes.toString(table.get(get3).list().get(0).getValue()),is("yedu")); //查询nickname的多个(本示例为2个)版本值 Get get4 = new Get(Bytes.toBytes("1")); get4.addColumn(Bytes.toBytes("author"), Bytes.toBytes("nickname")); get4.setMaxVersions(2); List results = table.get(get4).list(); assertThat(results.size(),is(2)); assertThat(Bytes.toString(results.get(0).getValue()),is("yedu")); assertThat(Bytes.toString(results.get(1).getValue()),is("一叶渡江"));删除记录/**=========删除记录=========*/ //删除指定column Delete deleteColumn = new Delete(Bytes.toBytes("1")); deleteColumn.deleteColumns(Bytes.toBytes("author"),Bytes.toBytes("nickname")); table.delete(deleteColumn); assertThat( table.get(get4).list(),nullValue()); //删除所有column Delete deleteAll = new Delete(Bytes.toBytes("1")); table.delete(deleteAll); assertThat(table.getScanner(scan).next(),nullValue());删除表/**=========删除表=========*/ admin.disableTable("blog"); admin.deleteTable("blog"); assertThat(admin.tableExists("blog"),is(false));完整代码示例public class HBase { public static void main(String[] args) throws IOException { Configuration conf = new Configuration(); // conf.addResource("hbase-site-cluster.xml");//指定文件加载 conf = HBaseConfiguration.create(conf); HBaseAdmin admin = new HBaseAdmin(conf);//HBaseAdmin负责跟表相关的操作如create,drop等 HTable table = new HTable(conf, Bytes.toBytes("blog"));//HTabel负责跟记录相关的操作如增删改查等 /**========创建表=========*/ HTableDescriptor desc = new HTableDescriptor("blog"); desc.addFamily(new HColumnDescriptor("article")); desc.addFamily(new HColumnDescriptor("author")); admin.createTable(desc ); /**=========插入数据=========*/ Put put = new Put(Bytes.toBytes("1")); put.add(Bytes.toBytes("article"), Bytes.toBytes("title"), Bytes.toBytes("Head First HBase")); put.add(Bytes.toBytes("article"), Bytes.toBytes("content"), Bytes.toBytes("HBase is the Hadoop database. Use it when you need random, realtime read/write access to your Big Data.")); put.add(Bytes.toBytes("article"), Bytes.toBytes("tags"), Bytes.toBytes("Hadoop,HBase,NoSQL")); put.add(Bytes.toBytes("author"), Bytes.toBytes("name"), Bytes.toBytes("hujinjun")); put.add(Bytes.toBytes("author"), Bytes.toBytes("nickname"), Bytes.toBytes("一叶渡江")); table.put(put); /**=========根据rowkey Get get = new Get(Bytes.toBytes("1")); 查询数据=========*/ Result result = table.get(get); for(KeyValue kv :result.list()){ System.out.println("family:" +Bytes.toString(kv.getFamily())); System.out.println("qualifier:" +Bytes.toString(kv.getQualifier())); System.out.println("value:" +Bytes.toString(kv.getValue())); System.out.println("Timestamp:" +kv.getTimestamp()); } /**=========遍历查询=========*/ Scan scan = new Scan(); ResultScanner rs =null; try { rs = table.getScanner(scan); for (Result r : rs) { for(KeyValue kv :r.list()){ System.out.println("family:" +Bytes.toString(kv.getFamily())); System.out.println("qualifier:" +Bytes.toString(kv.getQualifier())); System.out.println("value:" +Bytes.toString(kv.getValue())); } } } finally { rs.close(); } /**=========更新=========*/ //查询更新前的值 Get get2 = new Get(Bytes.toBytes("1")); get2.addColumn(Bytes.toBytes("author"), Bytes.toBytes("nickname")); assertThat(Bytes.toString(table.get(get2).list().get(0).getValue()),is("一叶渡江")); //更新nickname为yedu Put put2 = new Put(Bytes.toBytes("1")); : put2.add(Bytes.toBytes("author"), Bytes.toBytes("nickname"), Bytes.toBytes("yedu")); table.put(put2); //查询更新结果 Get get3 = new Get(Bytes.toBytes("1")); get3.addColumn(Bytes.toBytes("author"), Bytes.toBytes("nickname")); assertThat(Bytes.toString(table.get(get3).list().get(0).getValue()),is("yedu")); //查询nickname的多个(本示例为2个)版本值 Get get4 = new Get(Bytes.toBytes("1")); get4.addColumn(Bytes.toBytes("author"), Bytes.toBytes("nickname")); get4.setMaxVersions(2); List results = table.get(get4).list(); assertThat(results.size(),is(2)); assertThat(Bytes.toString(results.get(0).getValue()),is("yedu")); assertThat(Bytes.toString(results.get(1).getValue()),is("一叶渡江")); /**=========删除记录=========*/ //删除指定column Delete deleteColumn = new Delete(Bytes.toBytes("1")); deleteColumn.deleteColumns(Bytes.toBytes("author"),Bytes.toBytes("nickname")); table.delete(deleteColumn); assertThat( table.get(get4).list(),nullValue()); //删除所有column Delete deleteAll = new Delete(Bytes.toBytes("1")); table.delete(deleteAll); assertThat(table.getScanner(scan).next(),nullValue()); /**=========删除表=========*/ admin.disableTable("blog"); admin.deleteTable("blog"); assertThat(admin.tableExists("blog"),is(false)); } }小结
本文介绍了Java api创建、删除表，及记录的增删改查，还是以练习为主，也可作为速查手册（比如看如何迭代查询结果），对HBase的基本概念及操作就介绍到这里，后面将介绍如何使用MapReduce对HBase数据进行分布式计算。