实验三 熟悉常用的HBase操作
一、实验目的
(1)理解HBase在Hadoop体系结构中的角色;
(2)熟练使用HBase操作常用的Shell命令;
(3)熟悉HBase操作常用的Java API。
二、实验平台
操作系统:centos7;
Hadoop版本:3.3;
HBase版本:2.2.2;
JDK版本:1.8;
Java IDE:IDEA。
三、实验内容和要求
(一)编程实现以下指定功能,并用Hadoop提供的HBase Shell命令完成相同任务:
(1) 列出HBase所有的表的相关信息,例如表名、创建时间等;
(2) 在终端打印出指定的表的所有记录数据;
(3) 向已经创建好的表添加和删除指定的列族或列;
(4) 清空指定的表的所有记录数据;
(5) 统计表的行数。
(二)HBase数据库操作
1 现有以下关系型数据库中的表和数据,要求将其转换为适合于HBase存储的表并插入数据:
学生表(Student)
学号(S_No) | 姓名(S_Name) | 性别(S_Sex) | 年龄(S_Age) |
---|---|---|---|
2015001 | Zhangsan | male | 23 |
2015003 | Mary | female | 22 |
2015003 | Lisi | male | 24 |
课程表(Course)
课程号(C_No) | 课程名(C_Name) | 学分(C_Credit) |
---|---|---|
123001 | Math | 2.0 |
123002 | Computer | 5.0 |
123003 | English | 3.0 |
选课表(SC)
学号(SC_Sno) | 课程号(SC_Cno) | 成绩(SC_Score) |
---|---|---|
2015001 | 123001 | 86 |
2015001 | 123003 | 69 |
2015002 | 123002 | 77 |
2015002 | 123003 | 99 |
2015003 | 123001 | 98 |
2015003 | 123002 | 95 |
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 Main;
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 main {
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://127.0.0.1:8020/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();
}
}
}
运行结果
(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。
package Main;
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 main {
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://127.0.0.1:8020/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 = {"85","80","90"};
try{
addRecord("grade","S_Name",fields,values);
}catch(IOException e){
e.printStackTrace();
}
}
}
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
package Main;
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.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 main {
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:8020/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("test","id");
}
}
运行结果
(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。
package Main;
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 main{
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("test","1","score","100");
}
catch(Exception e){
e.printStackTrace();
}
}
}
运行结果
此时row为1的score已经改为100
(5)deleteRow(String tableName, String row)
删除表tableName中row指定的行的记录。
package Main;
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 main {
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:8020/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("test","2");
}catch(Exception e){
e.printStackTrace();
}
}
}
此时row=2已经被删除
出现的问题
问题一
在安装hbase后master-status用浏览器无法打开,而此时Hmaster和HregionServer,QuorumPeerMain已经启动
问题二
解决方法
问题一
在连接Hbase后使用list命令后发现如下
发现原因是因为我启动Hbase使用的不是hbase自带的zookeeper,而是自己独立安装的,在hbase-env.sh下增加
export HBASE_DISABLE_HADOOP_CLASSPATH_LOOKUP="true"
重新启动后
问题解决文章来源:https://www.toymoban.com/news/detail-759358.html
问题二
发现是maven导入包出现问题,再将hbase-client包换为2.5.3后问题解决
文章来源地址https://www.toymoban.com/news/detail-759358.html
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