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注:实验需要开启hbase服务,开启顺序为先Hadoop → Hbase,关闭顺序为Hbase → Hadoop
hbase(main):001:0> list
查看记录数据:
hbase(main):001:0> scan '表名'
查看表的信息:
hbase(main):001:0> describe '表名'
添加列族或列:
hbase(main):001:0> alter '表名','NAME'=>'列名'
删除列族或列:
hbase(main):001:0> alter '表名','NAME'=>'列名',METHOD=>'delete'
hbase(main):001:0> drop '表名'
hbase(main):001:0> count '表名'
学生表:
学号 | 姓名 | 性别 | 年龄 |
---|---|---|---|
2015001 | Zhangsan | male | 23 |
2015002 | Mary | female | 22 |
2015003 | Lisi | male | 24 |
课程表:
课程号 | 课程名 | 学分 |
---|---|---|
123001 | Math | 2.0 |
123002 | Computer Science | 5.0 |
123003 | English | 3.0 |
选课表:
学号 | 课程号 | 成绩 |
---|---|---|
2015001 | 123001 | 86 |
2015001 | 123003 | 69 |
2015002 | 123002 | 77 |
2015002 | 123003 | 99 |
2015003 | 123001 | 98 |
2015003 | 123002 | 95 |
创建三个表格
‘Student’表中添加数据
‘Course’表中添加数据
‘SC’表中添加数据
同时,请编程完成以下指定功能:
创建表,参数 tableName 为表的名称,字符串数组 fields 为存储记录各个域名称的数组。要求当 HBase 已经存在名为 tableName 的表的时候,先删除原有的表,然后再创建新的表。
import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.hbase.HBaseConfiguration; import org.apache.hadoop.hbase.TableName; import org.apache.hadoop.hbase.client.ColumnFamilyDescriptor; import org.apache.hadoop.hbase.client.ColumnFamilyDescriptorBuilder; import org.apache.hadoop.hbase.client.Connection; import org.apache.hadoop.hbase.client.Admin; import org.apache.hadoop.hbase.client.ConnectionFactory; import org.apache.hadoop.hbase.client.TableDescriptorBuilder; import org.apache.hadoop.hbase.util.Bytes; import java.io.IOException; public class CreateTable { public static Configuration configuration; public static Connection connection; public static Admin admin; public static void init(){//建立连接 configuration = HBaseConfiguration.create(); configuration.set("hbase.rootdir","hdfs://localhost:9000/hbase"); try{ connection = ConnectionFactory.createConnection(configuration); admin = connection.getAdmin(); }catch(IOException e){ e.printStackTrace(); } } public static void close(){//关闭连接 try{ if(admin != null){ admin.close(); } if(connection != null){ connection.close(); } }catch(IOException e){ e.printStackTrace(); } } public static void createTable(String tableName,String[] fields) throws IOException{ init(); TableName tablename = TableName.valueOf(tableName);//定义表名 if(admin.tableExists(tablename)){ System.out.println("table is exists!"); admin.disableTable(tablename); admin.deleteTable(tablename); } TableDescriptorBuilder tableDescriptor = TableDescriptorBuilder.newBuilder(tablename); for(int i=0;i<fields.length;i++){ ColumnFamilyDescriptor family = ColumnFamilyDescriptorBuilder.newBuilder(Bytes.toBytes(fields[i])).build(); tableDescriptor.setColumnFamily(family); } admin.createTable(tableDescriptor.build()); close(); } public static void main(String[] args){ String[] fields = {"id","score"}; try{ createTable("test",fields); }catch(IOException e){ e.printStackTrace(); } } }
向表 tableName、行 row(用 S_Name 表示)和字符串数组 fields 指定的单元格中添加对应的数据 values。其中 fields 中每个元素如果对应的列族下还有相应的列限定符的话,用 “columnFamily:column”表示。例如,同时向“Math”、“Computer Science”、“English” 三列添加成绩时,字符串数组 fields 为{“Score:Math”,“Score:Computer Science”, “Score:English”},数组 values 存储这三门课的成绩。
当向表添加数据时,我们需要一个Put对象,在Put对象之前我们需要获取Table对象,这样才能对指定的表进行操作
import java.io.IOException; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.hbase.HBaseConfiguration; import org.apache.hadoop.hbase.TableName; import org.apache.hadoop.hbase.client.Admin; import org.apache.hadoop.hbase.client.Connection; import org.apache.hadoop.hbase.client.ConnectionFactory; import org.apache.hadoop.hbase.client.Put; import org.apache.hadoop.hbase.client.Table; public class addRecord { public static Configuration configuration; public static Connection connection; public static Admin admin; public static void init(){//建立连接 configuration = HBaseConfiguration.create(); configuration.set("hbase.rootdir","hdfs://localhost:9000/hbase"); try{ connection = ConnectionFactory.createConnection(configuration); admin = connection.getAdmin(); }catch(IOException e){ e.printStackTrace(); } } public static void close(){//关闭连接 try{ if(admin != null){ admin.close(); } if(connection != null){ connection.close(); } }catch(IOException e){ e.printStackTrace(); } } public static void addRecord(String tableName,String row,String[] fields,String[] values) throws IOException{ init();//连接Hbase Table table = connection.getTable(TableName.valueOf(tableName));//表连接 Put put = new Put(row.getBytes());//创建put对象 for(int i=0;i<fields.length;i++){ String[] cols = fields[i].split(":"); if(cols.length == 1){ put.addColumn(fields[i].getBytes(),"".getBytes(),values[i].getBytes()); } else{ put.addColumn(cols[0].getBytes(),cols[1].getBytes(),values[i].getBytes()); } table.put(put);//向表中添加数据 } close();//关闭连接 } public static void main(String[] args){ String[] fields = {"Score:Math","Score:Computer Science","Score:English"}; String[] values = {"90","90","90"}; try{ addRecord("grade","S_Name",fields,values); }catch(IOException e){ e.printStackTrace(); } } }
由于没有创建这个表,所以只贴出代码,不再实验。
浏览表 tableName 某一列的数据,如果某一行记录中该列数据不存在,则返回 null。要求当参数 column 为某一列族名称时,如果底下有若干个列限定符,则要列出每个列限定符代表的列的数据;当参数 column 为某一列具体名称(例如“Score:Math”)时,只需要列出该列的数据。
import java.io.IOException; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.hbase.Cell; import org.apache.hadoop.hbase.CellUtil; import org.apache.hadoop.hbase.HBaseConfiguration; import org.apache.hadoop.hbase.TableName; import org.apache.hadoop.hbase.client.Admin; import org.apache.hadoop.hbase.client.Connection; import org.apache.hadoop.hbase.client.ConnectionFactory; import org.apache.hadoop.hbase.client.Get; 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.Table; import org.apache.hadoop.hbase.util.Bytes; public class scanColumn { public static Configuration configuration; public static Connection connection; public static Admin admin; public static void init(){//建立连接 configuration = HBaseConfiguration.create(); configuration.set("hbase.rootdir","hdfs://localhost:9000/hbase"); try{ connection = ConnectionFactory.createConnection(configuration); admin = connection.getAdmin(); }catch(IOException e){ e.printStackTrace(); } } public static void close(){//关闭连接 try{ if(admin != null){ admin.close(); } if(connection != null){ connection.close(); } }catch(IOException e){ e.printStackTrace(); } } public static void showResult(Result result){ Cell[] cells = result.rawCells(); for(int i=0;i<cells.length;i++){ System.out.println("RowName:"+new String(CellUtil.cloneRow(cells[i])));//打印行键 System.out.println("ColumnName:"+new String(CellUtil.cloneQualifier(cells[i])));//打印列名 System.out.println("Value:"+new String(CellUtil.cloneValue(cells[i])));//打印值 System.out.println("Column Family:"+new String(CellUtil.cloneFamily(cells[i])));//打印列簇 System.out.println(); } } public static void scanColumn(String tableName,String column){ init(); try { Table table = connection.getTable(TableName.valueOf(tableName)); Scan scan = new Scan(); scan.addFamily(Bytes.toBytes(column)); ResultScanner scanner = table.getScanner(scan); for(Result result = scanner.next();result != null;result = scanner.next()){ showResult(result); } } catch (IOException e) { e.printStackTrace(); } finally{ close(); } } public static void main(String[] args){ scanColumn("Student","S_Age"); } }
修改表 tableName,行 row(可以用学生姓名 S_Name 表示),列 column 指定的单元格的数据。
import java.io.IOException; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.hbase.HBaseConfiguration; import org.apache.hadoop.hbase.TableName; import org.apache.hadoop.hbase.client.Admin; import org.apache.hadoop.hbase.client.Connection; import org.apache.hadoop.hbase.client.ConnectionFactory; import org.apache.hadoop.hbase.client.Put; import org.apache.hadoop.hbase.client.Table; public class modifyData { public static Configuration configuration; public static Connection connection; public static Admin admin; public static void init(){//建立连接 configuration = HBaseConfiguration.create(); configuration.set("hbase.rootdir","hdfs://localhost:9000/hbase"); try{ connection = ConnectionFactory.createConnection(configuration); admin = connection.getAdmin(); }catch(IOException e){ e.printStackTrace(); } } public static void close(){//关闭连接 try{ if(admin != null){ admin.close(); } if(connection != null){ connection.close(); } }catch(IOException e){ e.printStackTrace(); } } public static void modifyData(String tableName,String row,String column,String value) throws IOException{ init(); Table table = connection.getTable(TableName.valueOf(tableName)); Put put = new Put(row.getBytes()); String[] cols = column.split(":"); if(cols.length == 1){ put.addColumn(column.getBytes(),"".getBytes(), value.getBytes()); } else{ put.addColumn(cols[0].getBytes(), cols[1].getBytes(), value.getBytes()); } table.put(put); close(); } public static void main(String[] args){ try{ modifyData("Student","1","S_Name","Tom"); } catch(Exception e){ e.printStackTrace(); } } }
删除表 tableName 中 row 指定的行的记录。
import java.io.IOException; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.hbase.HBaseConfiguration; import org.apache.hadoop.hbase.TableName; import org.apache.hadoop.hbase.client.Admin; import org.apache.hadoop.hbase.client.Connection; import org.apache.hadoop.hbase.client.ConnectionFactory; import org.apache.hadoop.hbase.client.Delete; import org.apache.hadoop.hbase.client.Table; public class deleteRow { public static Configuration configuration; public static Connection connection; public static Admin admin; public static void init(){//建立连接 configuration = HBaseConfiguration.create(); configuration.set("hbase.rootdir","hdfs://localhost:9000/hbase"); try{ connection = ConnectionFactory.createConnection(configuration); admin = connection.getAdmin(); }catch(IOException e){ e.printStackTrace(); } } public static void close(){//关闭连接 try{ if(admin != null){ admin.close(); } if(connection != null){ connection.close(); } }catch(IOException e){ e.printStackTrace(); } } public static void deleteRow(String tableName,String row) throws IOException{ init(); Table table = connection.getTable(TableName.valueOf(tableName)); Delete delete = new Delete(row.getBytes()); table.delete(delete); close(); } public static void main(String[] args){ try{ deleteRow("Student","3"); }catch(Exception e){ e.printStackTrace(); } } }
假设 HBase 有 2 张表,表的逻辑视图及部分数据如下所示:
书名(bookName) | 价格(price) |
---|---|
Database System Concept | 30$ |
Thinking in Java | 60$ |
Data Mining | 25$ |
创建表格
create "book","bookName
添加数据
put "book","30$","bookName:","Database System Concept"
put "book","60$","bookName:","Thinking in Java "
put "book","25$","bookName:","Data Mining "
查看表格
scan "book"
//表格默认根据keyRows按字典顺序排序
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