gcc-project-25-2/hbase-lesson/src/main/java/date_20250411/task_DML_select.java

package date_20250411;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.*;
import org.apache.hadoop.hbase.client.*;
import org.apache.hadoop.hbase.filter.Filter;
import org.apache.hadoop.hbase.filter.FilterList;
import org.apache.hadoop.hbase.filter.PrefixFilter;
import org.apache.hadoop.hbase.filter.SingleColumnValueFilter;
import org.apache.hadoop.hbase.util.Bytes;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;

public class task_DML_select {
    public static void main(String[] args) throws Exception {
        // create方法会自动去加载运行时的classpath中的hbase-site.xml等配置文件
        Configuration conf = HBaseConfiguration.create();
        conf.set("hbase.zookeeper.quorum", "hadoop102:2181");

        // 创建一个hbase的客户端连接
        Connection conn = ConnectionFactory.createConnection(conf);

        // 拿到一个DDL的操作工具
        Table table = conn.getTable(TableName.valueOf("ideaPro_space:students"));


        scanRows(table);

        // 关闭连接
        table.close();
        conn.close();
    }


    /**
     * 取一个指定的KeyValue
     *
     * @param table
     */
    public static void getKeyValue(Table table) throws IOException {


        String rowKey = "000010";

        Get getParam = new Get(Bytes.toBytes(rowKey));
        getParam.addColumn(Bytes.toBytes("base_info"), Bytes.toBytes("age"));


        Result result = table.get(getParam);

        byte[] value = result.getValue(Bytes.toBytes("base_info"), Bytes.toBytes("age"));

        int age = Bytes.toInt(value);

        System.out.println(age);

        table.close();

    }


    /**
     * get 单行中的指定列族的所有KeyValue数据
     *
     * @param table
     * @throws IOException
     */
    public static void getFamily(Table table) throws IOException {

        String rowKey = "000010";

        Get getParam = new Get(Bytes.toBytes(rowKey));
        getParam.addFamily(Bytes.toBytes("base_info"));

        Result result = table.get(getParam);
        CellScanner cellScanner = result.cellScanner();
        while (cellScanner.advance()) {
            // 一个cell就代表一个KeyValue
            Cell cell = cellScanner.current();

            byte[] rowKeyBytes = CellUtil.cloneRow(cell);
            byte[] familyBytes = CellUtil.cloneFamily(cell);
            byte[] qualifierBytes = CellUtil.cloneQualifier(cell);
            byte[] valueBytes = CellUtil.cloneValue(cell);

            String qualifier = Bytes.toString(qualifierBytes);
            String value = Bytes.toString(valueBytes);
            System.out.println(Bytes.toString(rowKeyBytes) + ","
                    + Bytes.toString(familyBytes) + ","
                    + qualifier + ","
                    + value
            );

        }

        table.close();

    }


    /**
     * 扫描指定行范围的数据
     *
     * @param table
     * @throws IOException
     */
    public static void scanRows(Table table) throws IOException {

        Scan scan = new Scan();
        String startMd5 = "001000";
        String stopMd5 = "002000";
        // 设置了扫描的起始行和结束行（默认含首不含尾）
        scan.withStartRow(Bytes.toBytes(startMd5));
        //scan.withStopRow(Bytes.toBytes(stopMd5),false);

        // 设置总共要扫描的行数
        scan.setLimit(100000);

        ResultScanner scanner = table.getScanner(scan);
        // 扫描时的  行 迭代器
        Iterator<Result> iterator = scanner.iterator();
        printData(iterator);

        table.close();
    }


    /**
     * 扫描多行数据，并带过滤条件
     *
     * @param table
     */
    public static void scanRowsWithFilter(Table table) throws IOException {
        Scan scan = new Scan();

        scan.withStartRow(Bytes.toBytes("000001"), true);
        scan.setLimit(10);

        // 行键前缀过滤器
        Filter filter1 = new PrefixFilter(Bytes.toBytes("cd"));  // 行键前缀过滤器

        // 列值过滤器（匹配到条件的行，整行数据都将返回）
        SingleColumnValueFilter filter2 = new SingleColumnValueFilter(Bytes.toBytes("extra_info"), Bytes.toBytes("city"), CompareOperator.EQUAL, Bytes.toBytes("南京"));

        ArrayList<Filter> filterList = new ArrayList<Filter>();
        filterList.add(filter1);
        filterList.add(filter2);

        // 将上面的2个过滤器，组成一个 MUST_PASS_ALL 关系的过滤器组
        FilterList filters = new FilterList(FilterList.Operator.MUST_PASS_ALL, filterList);
        //FilterListWithAND filters = new FilterListWithAND(filterList);


        // 给scan参数设置过滤器条件
        scan.setFilter(filters);


        ResultScanner scanner = table.getScanner(scan);
        Iterator<Result> iterator = scanner.iterator();  // 拿到行迭代器

        printData(iterator);  // 迭代，并打印数据

        table.close();
    }


    /**
     * 用于打印 scan结果的工具方法
     *
     * @param iterator
     * @throws IOException
     */
    private static void printData(Iterator<Result> iterator) throws IOException {
        while (iterator.hasNext()) {  // 行迭代
            // 迭代到一行
            Result result = iterator.next();
            // 拿到行中的cell单元格的迭代器
            CellScanner cellScanner = result.cellScanner();
            // 用单元格迭代器，迭代行中的每一个cell（单元格，KeyValue）
            while (cellScanner.advance()) {   //  行内的keyValue迭代
                Cell cell = cellScanner.current();

                String rowKey = Bytes.toString(CellUtil.cloneRow(cell));
                String family = Bytes.toString(CellUtil.cloneFamily(cell));
                String qualifier = Bytes.toString(CellUtil.cloneQualifier(cell));
                String value = Bytes.toString(CellUtil.cloneValue(cell));
                System.out.println(rowKey + "," + family + "," + qualifier + "," + value);

            }
        }
    }


}