6.1.5、Hbase

**一个result代表一条数据，一个row_key 使用listcell获取该条数据所有cell，拿到每一个cell，遍历cell后数据是一列一列的cell，按列一个个取cell
for (Result result : scanner) {
    //获取所有的小cell，每一列
    List cells = result.listCells();**

@Test
public void getScan()throws Exception{
    Table table = connection.getTable(TableName.valueOf("students"));
    //创建一个scan对象，设置限制条件
    Scan scan = new Scan();
    scan.withStartRow("1500100800".getBytes());
    scan.withStopRow("1500100810".getBytes());
    scan.setLimit(5);
    //获取所有数据，传入一个scan对象
    ResultScanner scanner = table.getScanner(scan);
    //获取一条条数据
    for (Result result : scanner) {
        String row = Bytes.toString(result.getRow());
        String name = Bytes.toString(result.getValue("info".getBytes(), "name".getBytes()));
        String age = Bytes.toString(result.getValue("info".getBytes(), "age".getBytes()));
        String gender = Bytes.toString(result.getValue("info".getBytes(), "gender".getBytes()));
        String clazz = Bytes.toString(result.getValue("info".getBytes(), "clazz".getBytes()));
        String string = row+"t"+name+"t"+age+"t"+gender+"t"+clazz;
        System.out.println(string);
    }
    connection.close();

@Test
public void putAll() throws Exception {
    //创建一张students表
    Admin admin = connection.getAdmin();
    if (!admin.tableExists(TableName.valueOf("students"))) {
        HTableDescriptor tableDescriptor = new HTableDescriptor(TableName.valueOf("students"));
        HColumnDescriptor info = new HColumnDescriptor("info");
        tableDescriptor.addFamily(info);
        admin.createTable(tableDescriptor);
    }
    Table table = connection.getTable(TableName.valueOf("students"));
    //使用list集合批处理快一些
    ArrayList list = new ArrayList();
    //IO流读写数据
    BufferedReader br = new BufferedReader(
            new FileReader("D:\Program Files\IDEA\IdeaProject\shujiabigdata\data\students.txt"));
    String line;
    int batche=10;
    while ((line = br.readLine()) != null) {
            String[] split = line.split(",");
            String id = split[0];
            String name = split[1];
            String age = split[2];
            String gender = split[3];
            String clazz = split[4];
            Put put = new Put(id.getBytes());
            put.addColumn("info".getBytes(), "name".getBytes(), name.getBytes());
            put.addColumn("info".getBytes(), "age".getBytes(), age.getBytes());
            put.addColumn("info".getBytes(), "gender".getBytes(), gender.getBytes());
            put.addColumn("info".getBytes(), "clazz".getBytes(), clazz.getBytes());
            list.add(put);
            //10条数据写一次
        if (list.size()==batche){
            table.put(list);
            list=new ArrayList();
        }
    }
    if (list.size()!=0){
        table.put(list);
    }
    connection.close();
}

适用数据结构不唯一的情况，获取每一个cell
001，sex：asd
输出可能会出现空值

//获取所有数据，传入一个scan对象
ResultScanner scanner = table.getScanner(scan);
//获取一条条数据
for (Result result : scanner) {
    //获取所有的小cell，每一列
    List cells = result.listCells();
    //获取row key
    String row_key = Bytes.toString(result.getRow());
    System.out.print(row_key+"t");
    
    //遍历，得到每一个cell
    for (Cell cell : cells) {
        //获取每一个cell的值
        String string = Bytes.toString(CellUtil.clonevalue(cell));
        //获取每一个cell的字段名
        String que = Bytes.toString(CellUtil.cloneQualifier(cell));
        if ("age".equals(que)){
            if (Integer.parseInt(string)>=20){
                string="成年";
            }
        }
        System.out.print(string+"t");
    }
    System.out.println();
}
connection.close();

设置get.setMaxVersions(3);
结果集需要使用list得到
Result result = table.get(get);
List cells = result.listCells();

@Test
public void getGet()throws Exception{
    Get get = new Get("47BE1E866CFC071DB19D5E1C056BE28AE24C16E7".getBytes());
    get.setMaxVersions(3);
    Result result = table.get(get);
    List cells = result.listCells();
    ArrayList jingduList = new ArrayList();
    ArrayList weiduList = new ArrayList();
    byte[] row = result.getRow();
    String rows = Bytes.toString(row);
    for (Cell cell : cells) {
        //获取值
        byte[] bytes = CellUtil.clonevalue(cell);
        String value = Bytes.toString(bytes);

        //获取列名
        byte[] bytes1 = CellUtil.cloneQualifier(cell);
        String que = Bytes.toString(bytes1);
        if ("jingdu".equals(que)){
            jingduList.add(value);
        }else {
            weiduList.add(value);
        }
    }
    for (int i = 0; i < 3; i++) {
        System.out.println(rows+"t"+jingduList.get(i)+"t"+weiduList.get(i));
    }
}