十四、HBase 数据库设计之 RowKey第2关车联网 RowKey 设计package step2;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.*;import org.apache.hadoop.hbase.util.Bytes;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;import java.util.HashMap;import java.util.Map;public class Task {static String[] chars {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, c, d, e, f};/*** MD5 加密* param str 需要加密的文本* return 加密后的32位md5字符串*/public static String StringInMd5(String str) {MessageDigest md5 null;try {md5 MessageDigest.getInstance(md5);byte[] result md5.digest(str.getBytes());StringBuilder sb new StringBuilder(32);for (int i 0; i result.length; i) {byte x result[i];int h 0x0f (x 4);int l 0x0f x;sb.append(chars[h]).append(chars[l]);}return sb.toString();} catch (NoSuchAlgorithmException e) {throw new RuntimeException(e);}}/*** 生成 row** param carId 汽车ID* param timestamp 时间戳* return rowkey 格式5位md5前缀-carId-timestamp*/public String createRowKey(String carId, String timestamp) {/********** begin **********/// 1. MD5车辆ID固定32位不会为空String md5Full StringInMd5(carId);// 截取前5位哈希前缀String prefix md5Full.substring(0, 5);// 严格拼接三段分隔符保证一定有值杜绝空串String rowKey prefix - carId - timestamp;return rowKey;/********** end **********/}/*** 查询某辆车在某个时间范围的交易记录** param carId 车辆ID* param startTimestamp 开始时间戳* param endTimestamp 截止时间戳* return map 存储 (rowkey,value)*/public MapString, String findLogByTimestampRange(String carId, String startTimestamp, String endTimestamp) throws Exception {MapString, String map new HashMap();/********** begin **********/Configuration conf HBaseConfiguration.create();conf.set(hbase.zookeeper.quorum, localhost);// 计算当前车辆固定哈希前缀String fullMd5 StringInMd5(carId);String prefix fullMd5.substring(0, 5);String base prefix - carId -;// 构造Scan左右边界左闭右开String startRow base startTimestamp;long endTsNum Long.parseLong(endTimestamp);String stopRow base (endTsNum 1);Scan scan new Scan(Bytes.toBytes(startRow), Bytes.toBytes(stopRow));// 只读取需要的列减少IO防超时scan.addColumn(Bytes.toBytes(info), Bytes.toBytes(val));try (Connection conn ConnectionFactory.createConnection(conf);Table table conn.getTable(TableName.valueOf(car_data));ResultScanner scanner table.getScanner(scan)) {for (Result res : scanner) {String rk Bytes.toString(res.getRow());Cell cell res.getColumnLatestCell(Bytes.toBytes(info), Bytes.toBytes(val));String val Bytes.toString(CellUtil.cloneValue(cell));map.put(rk, val);}}/********** end **********/return map;}}有任何问题都可以随时关注私信