First, the purpose of the experiment
The experiment by using a terminal and a Java API for hbase be CRUD operations, to learn the structure of non-relational databases and how to operate, understand comparative non-relational databases and relational databases, know how to use a relational database Philippine hbase .
Second, the experiment content
The teacher gives the complete content as possible, how much do you write much
Third, experimental ideas, structures
In the first achieved under way in hbase Linux command line to build the table, CRUD operations
Then use Elipse using Java programming in hbase construction table, CRUD operations.
Fourth, the experimental results
HBase create command with create a table as follows:
At this point, that creates a "student" table attributes: Sname, Ssex, Sage, Sdept , course. Because HBase table will have a default attribute as a key line without the need to create your own default data after the first operation command to put the table name. After creating the "student" table, you can view basic information "student" table by the describe command. Screenshot execute the following command:
Then performs HBase additions change the search operation. When adding data, HBase will automatically add a time stamp data is added, when it needs to change, simply add the data directly, i.e. HBase will generate a new version, thereby completing "to" operation, the old version is still reservations, the system periodically garbage data, leaving only a few of the latest version, the version number of the saved can be specified when creating a table.
1. Add Data
HBase add data using the put command, Note: only one line of data is a column of a table, i.e. a cell to add a data, so the direct insertion shell command data efficiency is very low, in practical applications, generally using data programming operation.
In this case, add a table school student number 95001, named LiYing row of data, the line key to 95001. Because HBase table will have a default attribute as a key line without the need to create your own default data after the first operation command to put the table name.
In this case is the 95001 in the line course column group math column adds a data.
2. Delete Data
In the delete data operation with HBase delete command and deleteall, the difference between them: 1 delete for deleting a data, the reverse operation is put; 2 deleteall operable to delete the row of data...
At this point delete the student all the data in the table under the column Ssex 95001 line.
deleteall command
Deleteall 'student', '95001' command to delete the 95001 all the columns in a row, all of the data that is in the row.
3. View data
HBase has two commands for viewing data: 1 get command is used to view the table of a data line; 2 scan command is used to view all the data in a table.. .
get command
Returns data 'Student' table '95001' line.
scan command
This will return the 'student' entire data table.
You can also query the underlying historical data
Historical versions of a lookup table requires two steps.
(1). When you create a table, specifying the number of versions saved (assuming that is designated as 5)
. (2) insert the data and then update the data to produce historical versions of data, attention: Here are the insert and update data with the data put command
(3) When a query, the query specified number of historical versions. The default will check out the latest data. (Effective value of 1 to 5)
4. Delete table
Delete table has two steps, the first step to let the table is not available, the second step to delete the table.
Using Elipse programming for hbase additions and deletions to change search
Code:
1 import org.apache.hadoop.conf.Configuration; 2 import org.apache.hadoop.hbase.*; 3 import org.apache.hadoop.hbase.client.*; 4 import java.io.IOException; 5 6 public class ExampleForHbase 7 { 8 public static Configuration configuration; 9 public static Connection connection; 10 public static Admin admin; 11 12 //主函数中的语句请逐句执行，只需删除其前的//即可，如：执行insertRow时请将其他语句注释 13 public static void main(String[] args)throws IOException 14 { 15 //创建一个表，表名为Score，列族为sname,course 16 //createTable("Score",new String[]{"sname","course"}); 17 18 //在Score表中插入一条数据，其行键为95001,sname为Mary（因为sname列族下没有子列所以第四个参数为空） 19 //等价命令：put 'Score','95001','sname','Mary' 20 //insertRow("Score", "95001", "sname", "", "Mary"); 21 //在Score表中插入一条数据，其行键为95001,course:Math为88（course为列族，Math为course下的子列） 22 //等价命令：put 'Score','95001','score:Math','88' 23 //insertRow("Score", "95001", "course", "Math", "88"); 24 //在Score表中插入一条数据，其行键为95001,course:English为85（course为列族，English为course下的子列） 25 //等价命令：put 'Score','95001','score:English','85' 26 //insertRow("Score", "95001", "course", "English", "85"); 27 28 //1、删除Score表中指定列数据，其行键为95001,列族为course，列为Math 29 //执行这句代码前请deleteRow方法的定义中，将删除指定列数据的代码取消注释注释，将删除制定列族的代码注释 30 //等价命令：delete 'Score','95001','score:Math' 31 //deleteRow("Score", "95001", "course", "Math"); 32 33 //2、删除Score表中指定列族数据，其行键为95001,列族为course（95001的Math和English的值都会被删除） 34 //执行这句代码前请deleteRow方法的定义中，将删除指定列数据的代码注释，将删除制定列族的代码取消注释 35 //等价命令：delete 'Score','95001','score' 36 //deleteRow("Score", "95001", "course", ""); 37 38 //3、删除Score表中指定行数据，其行键为95001 39 //执行这句代码前请deleteRow方法的定义中，将删除指定列数据的代码注释，以及将删除制定列族的代码注释 40 //等价命令：deleteall 'Score','95001' 41 //deleteRow("Score", "95001", "", ""); 42 43 //查询Score表中，行键为95001，列族为course，列为Math的值 44 //getData("Score", "95001", "course", "Math"); 45 //查询Score表中，行键为95001，列族为sname的值（因为sname列族下没有子列所以第四个参数为空） 46 //getData("Score", "95001", "sname", ""); 47 48 //删除Score表 49 //deleteTable("Score"); 50 } 51 52 //建立连接 53 public static void init() 54 { 55 configuration = HBaseConfiguration.create(); 56 configuration.set("hbase.rootdir","hdfs://localhost:9000/hbase"); 57 try 58 { 59 connection = ConnectionFactory.createConnection(configuration); 60 admin = connection.getAdmin(); 61 } 62 catch (IOException e) 63 { 64 e.printStackTrace(); 65 } 66 } 67 //关闭连接 68 public static void close() 69 { 70 try 71 { 72 if(admin != null) 73 { 74 admin.close(); 75 } 76 if(null != connection) 77 { 78 connection.close(); 79 } 80 } 81 catch (IOException e) 82 { 83 e.printStackTrace(); 84 } 85 } 86 87 /** 88 * 建表。HBase的表中会有一个系统默认的属性作为主键，主键无需自行创建，默认为put命令操作中表名后第一个数据，因此此处无需创建id列 89 * @param myTableName 表名 90 * @param colFamily 列族名 91 * @throws IOException 92 */ 93 public static void createTable(String myTableName,String[] colFamily) throws IOException 94 { 95 96 init(); 97 TableName tableName = TableName.valueOf(myTableName); 98 99 if(admin.tableExists(tableName)) 100 { 101 System.out.println("talbe is exists!"); 102 } 103 else 104 { 105 HTableDescriptor hTableDescriptor = new HTableDescriptor(tableName); 106 for(String str:colFamily) 107 { 108 HColumnDescriptor hColumnDescriptor = new HColumnDescriptor(str); 109 hTableDescriptor.addFamily(hColumnDescriptor); 110 } 111 admin.createTable(hTableDescriptor); 112 System.out.println("create table success"); 113 } 114 close(); 115 } 116 /** 117 * 删除指定表 118 * @param tableName 表名 119 * @throws IOException 120 */ 121 public static void deleteTable(String tableName) throws IOException 122 { 123 init(); 124 TableName tn = TableName.valueOf(tableName); 125 if (admin.tableExists(tn)) 126 { 127 admin.disableTable(tn); 128 admin.deleteTable(tn); 129 } 130 close(); 131 } 132 133 /** 134 * 查看已有表 135 * @throws IOException 136 */ 137 public static void listTables() throws IOException 138 { 139 init(); 140 HTableDescriptor hTableDescriptors[] = admin.listTables(); 141 for(HTableDescriptor hTableDescriptor :hTableDescriptors) 142 { 143 System.out.println(hTableDescriptor.getNameAsString()); 144 } 145 close(); 146 } 147 /** 148 * 向某一行的某一列插入数据 149 * @param tableName 表名 150 * @param rowKey 行键 151 * @param colFamily 列族名 152 * @param col 列名（如果其列族下没有子列，此参数可为空） 153 * @param val 值 154 * @throws IOException 155 */ 156 public static void insertRow(String tableName,String rowKey,String colFamily,String col,String val) throws IOException 157 { 158 init(); 159 Table table = connection.getTable(TableName.valueOf(tableName)); 160 Put put = new Put(rowKey.getBytes()); 161 put.addColumn(colFamily.getBytes(), col.getBytes(), val.getBytes()); 162 table.put(put); 163 table.close(); 164 close(); 165 } 166 167 /** 168 * 删除数据 169 * @param tableName 表名 170 * @param rowKey 行键 171 * @param colFamily 列族名 172 * @param col 列名 173 * @throws IOException 174 */ 175 public static void deleteRow(String tableName,String rowKey,String colFamily,String col) throws IOException 176 { 177 init(); 178 Table table = connection.getTable(TableName.valueOf(tableName)); 179 Delete delete = new Delete(rowKey.getBytes()); 180 //删除指定列族的所有数据 181 //delete.addFamily(colFamily.getBytes()); 182 //删除指定列的数据 183 //delete.addColumn(colFamily.getBytes(), col.getBytes()); 184 185 table.delete(delete); 186 table.close(); 187 close(); 188 } 189 /** 190 * 根据行键rowkey查找数据 191 * @param tableName 表名 192 * @param rowKey 行键 193 * @param colFamily 列族名 194 * @param col 列名 195 * @throws IOException 196 */ 197 public static void getData(String tableName,String rowKey,String colFamily,String col)throws IOException 198 { 199 init(); 200 Table table = connection.getTable(TableName.valueOf(tableName)); 201 Get get = new Get(rowKey.getBytes()); 202 get.addColumn(colFamily.getBytes(),col.getBytes()); 203 Result result = table.get(get); 204 showCell(result); 205 table.close(); 206 close(); 207 } 208 /** 209 * 格式化输出 210 * @param result 211 */ 212 public static void showCell(Result result) 213 { 214 Cell[] cells = result.rawCells(); 215 for(Cell cell:cells) 216 { 217 System.out.println("RowName:"+new String(CellUtil.cloneRow(cell))+" "); 218 System.out.println("Timetamp:"+cell.getTimestamp()+" "); 219 System.out.println("column Family:"+new String(CellUtil.cloneFamily(cell))+" "); 220 System.out.println("row Name:"+new String(CellUtil.cloneQualifier(cell))+" "); 221 System.out.println("value:"+new String(CellUtil.cloneValue(cell))+" "); 222 } 223 } 224 }
建表成功
在执行完代码中的所有插入操作以后可以看到表中数据为：
执行三个不同层次的删除操作后表中已经没有数据了
再重新执行一个插入数据的操作
然后执行第一个getData操作
再执行第二个getData操作
最后删除表。
五、 心得体会
做实验的时候要细心，注意具体导入的是哪个地方的jar包