hbase数据库scan操作_hbase数据库操作

青旅半醒 2023-01-01 05:49 176阅读 0赞

2.请编程实现以下功能：

(1) createTable(String tableName, String\[\] fields)

创建表，参数 tableName 为表的名称，字符串数组 fields 为存储记录各个字段名称的数组。

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。

package cn.wl.edu.hbase;

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.TableName;

import org.apache.hadoop.hbase.client.Admin;

import org.apache.hadoop.hbase.client.Connection;

import org.apache.hadoop.hbase.client.ConnectionFactory;

import java.io.IOException;public classCreateTable \{public staticConfiguration configuration;public staticConnection connection;public staticAdmin admin;public static voidcreateTable(String tableName, String\[\] fields)

throws IOException \{

init();

TableName tablename=TableName.valueOf(tableName);if(admin.tableExists(tablename)) \{

System.out.println("table is exists!");

HTableDescriptor hTableDescriptor= newHTableDescriptor(tablename);for(String str : fields) \{

HColumnDescriptor hColumnDescriptor= newHColumnDescriptor(str);

hTableDescriptor.addFamily(hColumnDescriptor);

admin.createTable(hTableDescriptor);

close();

\}public static voidinit() \{

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 voidclose() \{try\{if (admin != null) \{

admin.close();

\}if (null !=connection) \{

connection.close();

\}catch(IOException e) \{

e.printStackTrace();

\}public static voidmain(String\[\] args) \{

String\[\] fields= \{ "Score"\};try\{

createTable("person", fields);

\}catch(IOException e) \{

e.printStackTrace();

(2)addRecord(String tableName, String row, String\[\] fields, String\[\] values

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。

源代码：

package cn.wl.edu.hbase;

import org.apache.hadoop.conf.Configuration;

import org.apache.hadoop.hbase.HBaseConfiguration;

import org.apache.hadoop.hbase.TableName;

import org.apache.hadoop.hbase.client.\*;

import java.io.IOException;public classaddRecord \{public staticConfiguration configuration;public staticConnection connection;public staticAdmin admin;public static voidaddRecord(String tableName, String row, String\[\] fields, String\[\] values) throws IOException \{

init();

Table table=connection.getTable(TableName.valueOf(tableName));for (int i = 0; i != fields.length; i++) \{

Put put= newPut(row.getBytes());

String\[\] cols= fields\[i\].split(":");

put.addColumn(cols\[0\].getBytes(), cols\[1\].getBytes(), values\[i\].getBytes());

table.put(put);

table.close();

close();

\}public static voidinit() \{

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 voidclose() \{try\{if (admin != null) \{

admin.close();

\}if (null !=connection) \{

connection.close();

\}catch(IOException e) \{

e.printStackTrace();

\}public static voidmain(String\[\] args) \{

String\[\] fields= \{"Score:Math", "Score:Computer Science", "Score:English"\};

String\[\] values= \{"99", "80", "100"\};try\{

addRecord("person", "Score", fields, values);

\}catch(IOException e) \{

e.printStackTrace();

System.out.println("finish!");

(3) scanColumn(String tableName, String column)

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。

源代码：

package cn.wl.edu.hbase;

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.\*;

import org.apache.hadoop.hbase.util.Bytes;

import java.io.IOException;public classScanColumn \{public staticConfiguration configuration;public staticConnection connection;public staticAdmin admin;public static voidscanColumn(String tableName, String column) throws IOException \{

init();

Table table=connection.getTable(TableName.valueOf(tableName));

Scan scan= newScan();

scan.addFamily(Bytes.toBytes(column));

ResultScanner scanner=table.getScanner(scan);for (Result result = scanner.next(); result != null; result =scanner.next()) \{

showCell(result);

System.out.println("finish!");

table.close();

close();

\}public static voidshowCell(Result result) \{

Cell\[\] cells=result.rawCells();for(Cell cell : cells) \{

System.out.println("RowName:" + new String(CellUtil.cloneRow(cell)) + " ");

System.out.println("Timetamp:" + cell.getTimestamp() + " ");

System.out.println("column Family:" + new String(CellUtil.cloneFamily(cell)) + " ");

System.out.println("row Name:" + new String(CellUtil.cloneQualifier(cell)) + " ");

System.out.println("value:" + new String(CellUtil.cloneValue(cell)) + " ");

\}public static voidinit() \{

configuration=HBaseConfiguration.create();

configuration.set("hbase.rootdir", "hdfs://localhost:9000/hbase");try\{

connection=ConnectionFactory.createConnection(configuration);

admin=connection.getAdmin();

\}catch(IOException e) \{

e.printStackTrace();

\}//关闭连接

public static voidclose() \{try\{if (admin != null) \{

admin.close();

\}if (null !=connection) \{

connection.close();

\}catch(IOException e) \{

e.printStackTrace();

\}public static voidmain(String\[\] args) \{try\{

scanColumn("person", "Score");

\}catch(IOException e) \{

e.printStackTrace();

(4) modifyData(String tableName, String row, String column)

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。

源代码：

package cn.wl.edu.hbase;

import org.apache.hadoop.conf.Configuration;

import org.apache.hadoop.hbase.Cell;

import org.apache.hadoop.hbase.HBaseConfiguration;

import org.apache.hadoop.hbase.TableName;

import org.apache.hadoop.hbase.client.\*;

import java.io.IOException;public classModifyData \{public static longts;public staticConfiguration configuration;public staticConnection connection;public staticAdmin admin;public static voidmodifyData(String tableName, String row, String column, String val) throws IOException \{

init();

Table table=connection.getTable(TableName.valueOf(tableName));

Put put= newPut(row.getBytes());

Scan scan= newScan();

ResultScanner resultScanner=table.getScanner(scan);for(Result r : resultScanner) \{for(Cell cell : r.getColumnCells(row.getBytes(), column.getBytes())) \{

ts=cell.getTimestamp();

put.addColumn(row.getBytes(), column.getBytes(), ts, val.getBytes());

table.put(put);

System.out.println("modify successful!");

table.close();

close();

\}public static voidinit() \{

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 voidclose() \{try\{if (admin != null) \{

admin.close();

\}if (null !=connection) \{

connection.close();

\}catch(IOException e) \{

e.printStackTrace();

\}public static voidmain(String\[\] args) \{try\{

modifyData("person", "Score", "Math", "100");

\}catch(IOException e) \{

e.printStackTrace();

(5) deleteRow(String tableName, String row)

删除表 tableName 中 row 指定的行的记录。

源代码：

package cn.wl.edu.hbase;

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.\*;

import org.apache.hadoop.hbase.util.Bytes;public classDeleteRow \{public staticConfiguration configuration;public staticConnection connection;public staticAdmin admin;public static voiddeleteRow(String tableName, String rowKey, String colFamily, String col) throws IOException \{

init();

Table table=connection.getTable(TableName.valueOf(tableName));

Delete delete= newDelete(rowKey.getBytes());

delete.addFamily(Bytes.toBytes(colFamily));

delete.addColumn(Bytes.toBytes(colFamily), Bytes.toBytes(col));

table.delete(delete);

System.out.println("delete successful!");

table.close();

close();

\}public static voidinit() \{

configuration=HBaseConfiguration.create();

configuration.set("hbase.rootdir", "hdfs://localhost:9000/hbase");try\{