HBASE(三)

迈不过友情╰ 2022-06-06 12:43 178阅读 0赞

今天看了一个人的博客 返现自己对HBASE了解还是太out了

下面补充一些概念 和新 API

\*\*1.\*\*NameSpace:相当于数据库 以前一直好奇 为什么HBASE 只有表 现在明白了 还有表空间 就相当于数据库 对应hadoop目录下的一个文件

//创建表空间 
    create_namespace '名字'
    //删除表空间 表空间中必须是空的
    drop_namespace '名字'

新的API 获取 连接的方式也不同

//我手打的 粘贴有错自己改：
    //创建conf
    Configuration conf = HBaseConfiguration.create();
     conf.set("hbase.zookeeper.quorum","hadoop01:2181,hadoop02:2181,hadoop03:2181");
    //获取连接 
    Connection conn = ConnectionFactory.createConnection(conf);
    
    
    这个conn 就能获取admin  
    Admin admin = conn.getAdmin();
    
    admin 可以根据表名获得表     创建表空间   等等 就和旧API一样了
    conn 也能获的表  获得admin

创建表空间：

/** * 创建命名空间 * @throws Exception */
        @Test
        public void createNameSpace() throws Exception{
            Admin admin = conn.getAdmin();
            NamespaceDescriptor namespace = NamespaceDescriptor.create("NAMESPACE").build();
            admin.createNamespace(namespace);
            admin.close();
        }

**2.**创建表的新API 采用TableName

/** * 创建表 */
        @Test
        public void createTable() throws Exception{
            Admin admin = conn.getAdmin();
            TableName tableName = TableName.valueOf("NAMESPACE","TABLE1");
            HTableDescriptor table = new HTableDescriptor(tableName);
            HColumnDescriptor colfam1 = new HColumnDescriptor("colfam1");
            HColumnDescriptor colfam2 = new HColumnDescriptor("colfam2");
            table.addFamily(colfam1);
            table.addFamily(colfam2);
            admin.createTable(table);
            admin.close();
    
        }

命令行的形式:

create 'NAMESPACE:TABLE2','colfam1','colfam2'

**3.**查看数据库信息

命令行是 list
    
    api:
      @Test
        public void list() throws Exception{
            Admin admin = conn.getAdmin();
            //获取所有的命名空间
            NamespaceDescriptor[] namespaceDescriptors = admin.listNamespaceDescriptors();
            for (NamespaceDescriptor namespaceDescriptor : namespaceDescriptors) {
                System.out.println(namespaceDescriptor.getName());
            }
        }
         System.out.println("------------------------");
    //获取 给定命名空间下的表
            TableName[] tableNames = admin.listTableNamesByNamespace("NAMESPACE");
            for (TableName tableName : tableNames) {
                System.out.println(tableName.getNameAsString());
            }
       System.out.println("------------------------");
       //利用正则获得表
            Pattern pattern = Pattern.compile("NAMESPACE:.*");
            HTableDescriptor[] hTableDescriptors = admin.listTables(pattern);
            for (HTableDescriptor hTableDescriptor : hTableDescriptors) {
                System.out.println(hTableDescriptor);
            }

4.获取集群状态

ClusterStatus status = admin.getClusterStatus();

**5. 14个过滤器**  
5.1 RowFilter

/** * 行键过滤 RowFilter */
        @Test
        public void RowFilter() throws Exception {
            //建立与user表的连接
            Table user = conn.getTable(TableName.valueOf("user"));
    // CompareFilter.CompareOp 包含小于 等于 大于 <= >=
    
            // 1.BinaryComparator 当前的值
            RowFilter rowFilter1 = new RowFilter(CompareFilter.CompareOp.EQUAL, new BinaryComparator(Bytes.toBytes("813782218261011172")));
    
    //2.正则匹配RegexStringComparator
        RowFilter rowFilter2 = new RowFilter(CompareFilter.CompareOp.EQUAL, new RegexStringComparator("^.*1$"));
    
    //3.包含子串 
      RowFilter rowFilter3 = new RowFilter(CompareFilter.CompareOp.EQUAL, new SubstringComparator("3782"));
    
    
    
    
            Scan scan = new Scan();
            scan.addColumn(Bytes.toBytes("info"),Bytes.toBytes("age"));
            scan.setFilter(rowFilter1);
            ResultScanner scanner = user.getScanner(scan);
            for (Result result : scanner) {
                byte[] value = result.getValue(Bytes.toBytes("info"), Bytes.toBytes("age"));
                System.out.println(new String(value));
            }
    
    
        }

5.2 FamilyFilter 列族过滤器

FamilyFilter kk = new FamilyFilter(CompareFilter.CompareOp.GREATER, new BinaryComparator(Bytes.toBytes("kk")));

5.3 DependentColumnFilter 参考列过滤器  
以这一列为参考 在同列族中查找跟参考列时间戳一样的列

@Test
        public void depentCol() throws Exception{
            Table user = conn.getTable(TableName.valueOf("user"));
            Scan scan = new Scan();
            DependentColumnFilter filter = new DependentColumnFilter(Bytes.toBytes("info"), Bytes.toBytes("phone"), true, CompareFilter.CompareOp.EQUAL, new BinaryComparator(Bytes.toBytes("13213921424")));
            scan.setFilter(filter);
            ResultScanner scanner = user.getScanner(scan);
            for (Result result : scanner) {
                System.out.println(result);
            }
        }

5.4 PrefixFilter 前缀过滤器 根据行键的前缀进行过滤

/** * PrefixFilter 前缀过滤器 根据行键的前缀进行过滤 */
        @Test
        public void prefix() throws Exception{
            Table user = conn.getTable(TableName.valueOf("user"));
            Scan scan = new Scan();
            PrefixFilter prefixFilter = new PrefixFilter(Bytes.toBytes("2243"));
            scan.setFilter(prefixFilter);
            ResultScanner scanner = user.getScanner(scan);
            for (Result result : scanner) {
                System.out.println(result);
            }
    
    
        }

5.5 分页过滤器

/** * 分页过滤器 PageFilter */
        @Test
        public void pageFilter() throws IOException {
            Table user = conn.getTable(TableName.valueOf("user"));
            Scan scan = new Scan();
            PageFilter pageFilter = new PageFilter(2);
            scan.setFilter(pageFilter);
            ResultScanner scanner = user.getScanner(scan);
            for (Result result : scanner) {
                System.out.println(result);
            }
        }

5.6 KeyOnlyFilter 行键过滤器

//只返回行键 值都为空
       KeyOnlyFilter keyOnlyFilter = new KeyOnlyFilter();

5.7 FirstKeyOnlyFilter 首次行键过滤器 只返回第一列

FirstKeyOnlyFilter firstKeyOnlyFilter = new FirstKeyOnlyFilter();

5.8 InclusiveStopFilter 包含结束的过滤器

InclusiveStopFilter inclusiveStopFilter = new InclusiveStopFilter(Bytes.toBytes("510824118261011172"));

5.9 ColumnCountGetFilter 列计数过滤器  
给定列数  
从行第一列开始扫描 如果这一行 列数小于给定列数 继续扫描 否则程序结束

ColumnCountGetFilter columnCountGetFilter = new ColumnCountGetFilter(1);

5.10 ColumnPrefixFilter 列前缀过虑器

Filter cpf = new ColumnPrefixFilter(Bytes.toBytes("qual1")); // OK 筛选出前缀匹配的列

5.11 MultipleColumnPrefixFilter 多个列前缀过滤器

Filter filter = new MultipleColumnPrefixFilter(new byte[][] {Bytes.toBytes("a"),Bytes.toBytes("h")});