Java API 讀取HBase表資料

1.

在使用java api 去獲取資料的時候，先用 hbase shell 展示一下 hbase 中的表。

hbase(main):005:0> scan 'tsdb-uid'
ROW                                                 COLUMN+CELL                                                                                                                                           
 \x00                                               column=
 
id:metrics, timestamp=1541500656882, value=\x00\x00\x00\x00\x00\x00\x00\x05                                                                    
 \x00                                               column=id:tagk, timestamp=1535982247222, value=\x00\x00\x00\x00\x00
 ···
 \x00\x00\x08                                       column=name:tagv, timestamp=
 
1541425665725, value=firminal                                                                                             
 Firminal                                           column=id:tagv, timestamp=1537103490289, value=\x00\x00\x06                                                                                           
 accessNumber                                       column=
 
id:tagk, timestamp=1535982247235, value=\x00\x00\x03                                                                                           
 chl                                                column=id:tagk, timestamp=1535891521203, value=\x00\x00\x02                                                                                           
 cs                                                 column=id:tagv, timestamp=1535982247259, value=\x00x00\x05                                                                                           
 ···
25 row(s) in 0.0770 seconds

hbase(main):007:0> get 'tsdb-uid','cs'
COLUMN                                              CELL                                                                                                                                                  
 id:tagv                                            timestamp=1535982247259, value=\x00\x00\x05                                                                                                           
1 row(s) in 0.0240 seconds

通過觀察 tsdb-uid表，可以看到有一個 rowKey = cs，且其值為（hex）000005，那麼使用java api去獲取資料的程式碼如下：

2. 使用Java獲取HBase的資料

2.1 get方法

• 靜態變數

    public static Configuration conf ;
    private static Connection connection;
    private static Admin admin;

    //step2:you should set some properties
    //connection should be closed,but not
    static{
        System.out.println("Hello,static code is started...");
        conf = HBaseConfiguration.create();

        conf.set("hbase.zookeeper.quorum", "192.168.211.4");
        conf.set("hbase.zookeeper.property.clientPort", "2181");
        try {
            connection= ConnectionFactory.createConnection(conf);
        } catch (IOException e) {
            e.printStackTrace();
        }
        //new way to get an HBaseAdmin
        try {
            admin = connection.getAdmin();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

• get的使用

 public static void getRowFromTable(String tableName,String qualifier){
        try {
            Table table = connection.getTable(TableName.valueOf(tableName));
            byte[] row = new byte[]{};
            row = qualifier.getBytes();
            Get g = new Get(row);
            // Reading the data
            Result result = table.get(g);

            // Reading values from Result class object
            byte [] value1 = result.getValue(Bytes.toBytes("id"),Bytes.toBytes("tagv"));
            byte [] value2 = result.getValue(Bytes.toBytes("id"),Bytes.toBytes("timestamp"));

            for(int i = 0;i< value1.length;i++){
                System.out.print(value1[i]);
            }
            CustomedMethod.printDelimiter();

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

public static void main(String[] args) {
        try {
            System.setProperty("hadoop.home.dir", "D:\\SoftWarePackages\\BigData\\hadoop-2.6.4");    
            HBaseUtils.getRowFromTable("tsdb-uid","cs");
            HBaseUtils.closeAll();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

得到的結果如下：

2.2 scan方法