Java 操作 HBase 教程

Java 操作 HBase 教程

• 一、简介
• 二、hbase-client 引入
• 三、连接操作
• 四、表操作
• 五、运行测试

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相关博文原文地址：

博客园：美码师：HBase(2) Java 操作 HBase 教程

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一、简介

HBase 本身就是用 Java 编写的，天生自带了 Java 原生API。 我们可以通过 hbase-client 来实现 HBase 数据库的操作。

所以，这次主要介绍该组件的基本用法。

在使用 hbase-client 之前，有几个要点需要注意：

• 客户端需要能访问 Zoopkeeper，再获得 HMaster、RegionServer 实例进行操作
• 客户端需运行在HBase/Hadoop 集群内，HBase会使用 hostname 来定位节点，因此要求客户端能访问到对应的主机名(或子域名)
  
  如果是远程客户端则需要配置本地的hosts文件。

下面这个图，有助于理解 Client 与 HBase 集群的交互架构：

二、hbase-client 引入

在 Maven 的 pom.xml 中添加依赖：

<dependency>
    <groupId>org.apache.hbase</groupId>
    <artifactId>hbase-client</artifactId>
    <version>2.1.5</version>
    <exclusions>
        <exclusion>
            <artifactId>slf4j-api</artifactId>
            <groupId>org.slf4j</groupId>
        </exclusion>
        <exclusion>
            <artifactId>slf4j-log4j12</artifactId>
            <groupId>org.slf4j</groupId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>org.apache.hbase</groupId>
    <artifactId>hbase</artifactId>
    <version>2.1.5</version>
</dependency>

客户端版本和 HBase 版本需要保持一致，否则可能会遇到不兼容的问题。

三、连接操作

/**
 * 建立连接
 *
 * @return
 */
public static Connection getConnection() {
    try {
        //获取配置
        Configuration configuration = getConfiguration();
        //检查配置
        HBaseAdmin.checkHBaseAvailable(configuration);
        return ConnectionFactory.createConnection(configuration);
    } catch (IOException | ServiceException e) {
        throw new RuntimeException(e);
    }
}

/**
 * 获取配置
 *
 * @return
 */
private static Configuration getConfiguration() {
    try {
        Properties props = PropertiesLoaderUtils.loadAllProperties("hbase.properties");
        String clientPort = props.getProperty("hbase.zookeeper.property.clientPort");
        String quorum = props.getProperty("hbase.zookeeper.quorum");

        logger.info("connect to zookeeper {}:{}", quorum, clientPort);

        Configuration config = HBaseConfiguration.create();
        config.set("hbase.zookeeper.property.clientPort", clientPort);
        config.set("hbase.zookeeper.quorum", quorum);
        return config;
    } catch (IOException e) {
        throw new RuntimeException(e);
    }
}

四、表操作

增删改查方法封装如下：

/**
 * 创建表
 * @param connection
 * @param tableName
 * @param columnFamilies
 * @throws IOException
 */
public static void createTable(Connection connection, TableName tableName, String... columnFamilies) throws IOException {
    Admin admin = null;
    try {
        admin = connection.getAdmin();
        if (admin.tableExists(tableName)) {
            logger.warn("table:{} exists!", tableName.getName());
        } else {
            TableDescriptorBuilder builder = TableDescriptorBuilder.newBuilder(tableName);
            for (String columnFamily : columnFamilies) {
                builder.setColumnFamily(ColumnFamilyDescriptorBuilder.of(columnFamily));
            }
            admin.createTable(builder.build());
            logger.info("create table:{} success!", tableName.getName());
        }
    } finally {
        if (admin != null) {
            admin.close();
        }
    }
}

/**
 * 插入数据
 *
 * @param connection
 * @param tableName
 * @param rowKey
 * @param columnFamily
 * @param column
 * @param data
 * @throws IOException
 */
public static void put(Connection connection, TableName tableName,
                       String rowKey, String columnFamily, String column, String data) throws IOException {

    Table table = null;
    try {
        table = connection.getTable(tableName);
        Put put = new Put(Bytes.toBytes(rowKey));
        put.addColumn(Bytes.toBytes(columnFamily), Bytes.toBytes(column), Bytes.toBytes(data));
        table.put(put);
    } finally {
        if (table != null) {
            table.close();
        }
    }
}

/**
 * 根据row key、column 读取
 *
 * @param connection
 * @param tableName
 * @param rowKey
 * @param columnFamily
 * @param column
 * @throws IOException
 */
public static String getCell(Connection connection, TableName tableName, String rowKey, String columnFamily, String column) throws IOException {
    Table table = null;
    try {
        table = connection.getTable(tableName);
        Get get = new Get(Bytes.toBytes(rowKey));
        get.addColumn(Bytes.toBytes(columnFamily), Bytes.toBytes(column));

        Result result = table.get(get);
        List<Cell> cells = result.listCells();

        if (CollectionUtils.isEmpty(cells)) {
            return null;
        }
        String value = new String(CellUtil.cloneValue(cells.get(0)), "UTF-8");
        return value;
    } finally {
        if (table != null) {
            table.close();
        }
    }
}

/**
 * 根据rowkey 获取一行
 *
 * @param connection
 * @param tableName
 * @param rowKey
 * @return
 * @throws IOException
 */
public static Map<String, String> getRow(Connection connection, TableName tableName, String rowKey) throws IOException {
    Table table = null;
    try {
        table = connection.getTable(tableName);
        Get get = new Get(Bytes.toBytes(rowKey));

        Result result = table.get(get);
        List<Cell> cells = result.listCells();

        if (CollectionUtils.isEmpty(cells)) {
            return Collections.emptyMap();
        }
        Map<String, String> objectMap = new HashMap<>();
        for (Cell cell : cells) {
            String qualifier = new String(CellUtil.cloneQualifier(cell));
            String value = new String(CellUtil.cloneValue(cell), "UTF-8");
            objectMap.put(qualifier, value);
        }
        return objectMap;
    } finally {
        if (table != null) {
            table.close();
        }
    }
}

/**
 * 扫描权标的内容
 *
 * @param connection
 * @param tableName
 * @param rowkeyStart
 * @param rowkeyEnd
 * @throws IOException
 */
public static List<Map<String, String>> scan(Connection connection, TableName tableName, String rowkeyStart, String rowkeyEnd) throws IOException {
    Table table = null;
    try {
        table = connection.getTable(tableName);
        ResultScanner rs = null;
        try {
            Scan scan = new Scan();
            if (!StringUtils.isEmpty(rowkeyStart)) {
                scan.withStartRow(Bytes.toBytes(rowkeyStart));
            }
            if (!StringUtils.isEmpty(rowkeyEnd)) {
                scan.withStopRow(Bytes.toBytes(rowkeyEnd));
            }
            rs = table.getScanner(scan);

            List<Map<String, String>> dataList = new ArrayList<>();
            for (Result r : rs) {
                Map<String, String> objectMap = new HashMap<>();
                for (Cell cell : r.listCells()) {
                    String qualifier = new String(CellUtil.cloneQualifier(cell));
                    String value = new String(CellUtil.cloneValue(cell), "UTF-8");
                    objectMap.put(qualifier, value);
                }
                dataList.add(objectMap);
            }
            return dataList;
        } finally {
            if (rs != null) {
                rs.close();
            }
        }
    } finally {
        if (table != null) {
            table.close();
        }
    }
}

/**
 * 删除表
 *
 * @param connection
 * @param tableName
 * @throws IOException
 */
public static void deleteTable(Connection connection, TableName tableName) throws IOException {
    Admin admin = null;
    try {
        admin = connection.getAdmin();
        if (admin.tableExists(tableName)) {
            //现执行disable
            admin.disableTable(tableName);
            admin.deleteTable(tableName);
        }
    } finally {
        if (admin != null) {
            admin.close();
        }
    }
}

五、运行测试

1. 建立 DeviceState 表；
2. 定义 name/state 两个列簇；
3. 写入列数据；
4. 读取列、行，范围读取；
5. 删除操作

private static final Logger logger = LoggerFactory.getLogger(HBaseTest.class);

public static void main(String[] args) {

    Connection connection = null;
    try {
        connection = getConnection();
        TableName tableName = TableName.valueOf("DeviceState");

        //创建DeviceState表
        createTable(connection, tableName, "name", "state");

        logger.info("创建表 {}", tableName.getNameAsString());

        //写入数据
        put(connection, tableName, "row1", "name", "c1", "空调");
        put(connection, tableName, "row1", "state", "c2", "打开");
        put(connection, tableName, "row2", "name", "c1", "电视机");
        put(connection, tableName, "row2", "state", "c2", "关闭");

        logger.info("写入数据.");

        String value = getCell(connection, tableName, "row1", "state", "c2");
        logger.info("读取单元格-row1.state:{}", value);

        Map<String, String> row = getRow(connection, tableName, "row2");
        logger.info("读取单元格-row2:{}", JsonUtil.toJson(row));

        List<Map<String, String>> dataList = scan(connection, tableName, null, null);
        logger.info("扫描表结果-:\n{}", JsonUtil.toPrettyJson(dataList));

        //删除DeviceState表
        deleteTable(connection, tableName);
        logger.info("删除表 {}", tableName.getNameAsString());

        logger.info("操作完成.");
    } catch (Exception e) {
        logger.error("操作出错", e);
    } finally {
        if (connection != null) {
            try {
                connection.close();
            } catch (IOException e) {
                logger.error("error occurs", e);
            }
        }
    }

}

执行代码，控制台输出如下：

INFO -createTable(HBaseTest.java:89) - create table:[68, 101, 118, 105, 99, 101, 83, 116, 97, 116, 101] success!
INFO -main(HBaseTest.java:32) - 创建表 DeviceState
INFO -main(HBaseTest.java:40) - 写入数据.
INFO -main(HBaseTest.java:43) - 读取单元格-row1.state:打开
INFO -main(HBaseTest.java:46) - 读取单元格-row2:{"c1":"电视机","c2":"关闭"}
INFO -main(HBaseTest.java:49) - 扫描表结果-:
[ {
  "c1" : "空调",
  "c2" : "打开"
}, {
  "c1" : "电视机",
  "c2" : "关闭"
} ]
INFO -HBaseAdmin$9.call(HBaseAdmin.java:1380) - Started disable of DeviceState
INFO -HBaseAdmin$DisableTableFuture.postOperationResult(HBaseAdmin.java:1409) - Disabled DeviceState
INFO -HBaseAdmin$DeleteTableFuture.postOperationResult(HBaseAdmin.java:965) - Deleted DeviceState
INFO -main(HBaseTest.java:53) - 删除表 DeviceState
INFO -main(HBaseTest.java:55) - 操作完成.