Hadoop大数据框架实践 （2）

前言

上文讨论了hdfs以及hbase和hadoop的操作，本篇旨在简单尝试使用hbase。

下载安装

首先下载mirrors.bfsu.edu.cn/apache/hbas… 下载以后打开解压文件，放在我们上次一样的文件夹然后解压打开 首先修改hbase-env.sh,把java_home 编辑修改进去

然后打开bin文件地址输入指令

./start-hbase.sh
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这样就是启动成功了。

Hbase主要注意的点只有两个：一个是修改配置文件。第二个是注意启动的hadoop集群的状态，如果看到日志中

 master.HMaster: Failed to become active master
java.net.ConnectException: Call From xuejiamengdeMacBook-Pro.local/192.168.2.40 to localhost:9000 failed on connection exception
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注意自己的hadoop启动状态，重新修复以后再启动就可以了。

在浏览器访问 localhost:16010 可以看到运行情况

使用

首先编写配置，因为我们是本地测试就直接设置 localhost

public static Connection createConnection() throws IOException {
    Configuration cfg = HBaseConfiguration.create();
    cfg.set("hbase.zookeeper.quorum", "localhost");
    return ConnectionFactory.createConnection(cfg);
}
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然后先编写创建表和命名空间的代码

public static void createTable(Connection connection,String myTableName,String[] colFamily) throws IOException{

    Admin admin = connection.getAdmin();
    TableName tableName=TableName.valueOf(myTableName);
    if (admin.tableExists(tableName)) {
        System.out.println("table is exist");
    }else {
        List<ColumnFamilyDescriptor> colFamilyList=new ArrayList<>();
        TableDescriptorBuilder tableDesBuilder=TableDescriptorBuilder.newBuilder(tableName);
        for(String str:colFamily) {
            ColumnFamilyDescriptor colFamilyDes=ColumnFamilyDescriptorBuilder.newBuilder(str.getBytes()).build();
            colFamilyList.add(colFamilyDes);
        }
        TableDescriptor tableDes=tableDesBuilder.setColumnFamilies(colFamilyList).build();
        admin.createTable(tableDes);
    }
}

public static void createNamespace(Connection connection, String tablespace) throws IOException {

    Admin admin = connection.getAdmin();
    admin.createNamespace(NamespaceDescriptor.create(tablespace).build());
    System.out.println("成功创建表空间 " + tablespace);
}
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测试一下

@Test
public void create() {
    try (Connection connection = HbaseService.createConnection();) {
        HbaseService.createNamespace(connection,"xuejm");
    } catch (IOException e) {
        e.printStackTrace();
    }
}
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创建表

public static void createTable(Connection connection,String myTableName,String[] colFamily) throws IOException{
    Admin admin = connection.getAdmin();
    TableName tableName=TableName.valueOf(myTableName);
    if (admin.tableExists(tableName)) {
        System.out.println("table is exist");
    }else {
        List<ColumnFamilyDescriptor> colFamilyList=new ArrayList<>();
        TableDescriptorBuilder tableDesBuilder=TableDescriptorBuilder.newBuilder(tableName);
        for(String str:colFamily) {
            ColumnFamilyDescriptor colFamilyDes=ColumnFamilyDescriptorBuilder.newBuilder(str.getBytes()).build();
            colFamilyList.add(colFamilyDes);
        }
        TableDescriptor tableDes=tableDesBuilder.setColumnFamilies(colFamilyList).build();
        admin.createTable(tableDes);
    }
}
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插入数据

public static void insert(Connection connection, String tableName, String rowKey, String columnFamily, String column,
                          String value) throws IOException {
    Table table = connection.getTable(TableName.valueOf(tableName));
    Put put = new Put(rowKey.getBytes());
    put.addColumn(columnFamily.getBytes(), column.getBytes(), value.getBytes());
    table.put(put);
}
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查询数据

public static void scan(Connection connection, String tableName) throws IOException {
    Table table = connection.getTable(TableName.valueOf(tableName));
    Scan scan = new Scan();
    ResultScanner scanner = table.getScanner(scan);
    Result tmp;
    while ((tmp = scanner.next()) != null) {
        List<Cell> cells = tmp.listCells();
        for (Cell cell : cells) {
            String rk = Bytes.toString(cell.getRowArray(), cell.getRowOffset(), cell.getRowLength());
            String cf = Bytes.toString(cell.getFamilyArray(), cell.getFamilyOffset(), cell.getFamilyLength());
            String column = Bytes.toString(cell.getQualifierArray(), cell.getQualifierOffset(), cell.getQualifierLength());
            String value = Bytes.toString(cell.getValueArray(), cell.getValueOffset(), cell.getValueLength());
            System.out.println(rk + "column:" + cf + ":" + column + ",value=" + value);
        }
    }
}
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测试一下插入以及查询数据

@Test
public void insert() {
    try (Connection connection = HbaseService.createConnection()) {
        HbaseService.insert(connection, "xuejm:student", "row1", "name", "", "xue");
        HbaseService.insert(connection, "xuejm:student", "row1", "info", "student_id", "1");
        HbaseService.insert(connection, "xuejm:student", "row1", "info", "class", "1");
        HbaseService.insert(connection, "xuejm:student", "row1", "score", "math", "75");
        HbaseService.insert(connection, "xuejm:student", "row2", "name", "", "wang");
        HbaseService.insert(connection, "xuejm:student", "row2", "info", "student_id", "2");
        HbaseService.insert(connection, "xuejm:student", "row2", "info", "class", "2");
        HbaseService.insert(connection, "xuejm:student", "row2", "score", "math", "80");
    } catch (IOException e) {
        e.printStackTrace();
    }
}
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测试一下删除row

@Test
public void deleteRow() {
    try (Connection connection = HbaseService.createConnection()){
        HbaseService.deleteRow(connection, "xuejm:student", "row1");
    } catch (IOException e) {
        e.printStackTrace();
    }
}
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再度查询数据果然被删除了

这样我们就完成了一个简单的增删改查的hbase的demo。