Hbase教程
maven依赖：
注：jar包冲突在hbase中经常遇到，有时需要排除一些依赖
<dependency>
<groupId>org.apache.hbase</groupId>
<artifactId>hbase-shaded-client</artifactId>
<version>1.2.6</version>
<!--<exclusions>-->
<!--<exclusion>-->
<!--<groupId>org.slf4j</groupId>-->
<!--<artifactId>slf4j-log4j12</artifactId>-->
<!--</exclusion>-->
<!--<exclusion>-->
<!--<groupId>log4j</groupId>-->
<!--<artifactId>log4j</artifactId>-->
<!--</exclusion>-->
<!--</exclusions>-->
</dependency>
创建链接
static Connection connection;
static {
try {
Configuration conf = HBaseConfiguration.create();
connection = ConnectionFactory.createConnection(conf);
} catch (IOException e) {
e.printStackTrace();
}
}
查询整个表
public static List<Map<String, String>> queryTable(String tableName) throws IOException {
List<Map<String, String>> returnResult = new ArrayList<>();
Table table = connection.getTable(TableName.valueOf(tableName));
ResultScanner scanner = table.getScanner(new Scan());
for (Result result : scanner) {
Map<String, String> item = new HashMap<>();
String row = new String(result.getRow());
item.put(Constants.hbaseRowKey, row);
List<Cell> listCells = result.listCells();
for (Cell cell : listCells) {
String key = new String(cell.getQualifierArray(), cell.getQualifierOffset(), cell
.getQualifierLength());
String value = new String(cell.getValueArray(), cell.getValueOffset(), cell
.getValueLength());
if (StringUtils.isBlank(key) || StringUtils.isBlank(value) || "null".equals(value.trim())) {
continue;
}
item.put(key, value);
}
returnResult.add(item);
}
return returnResult;
}
查询单条记录
public static Map<String, String> getData(String tableName, String rowKey) throws IOException {
Map<String, String> returnResult = new HashMap<>();
Table table = connection.getTable(TableName.valueOf(tableName));
Get get = new Get(rowKey.getBytes());
Result result = table.get(get);
if (result.getRow() == null) {
return null;
}
String row = new String(result.getRow());
returnResult.put(Constants.hbaseRowKey, row);
List<Cell> listCells = result.listCells();
for (Cell cell : listCells) {
String key = new String(cell.getQualifierArray(), cell.getQualifierOffset(), cell
.getQualifierLength());
String value = new String(cell.getValueArray(), cell.getValueOffset(), cell
.getValueLength());
if (StringUtils.isBlank(key) || StringUtils.isBlank(value) || "null".equals(value.trim())) {
continue;
}
if (key.matches("^pre\\d+_")) {
key = key.substring(key.indexOf("_") + 1);
}
returnResult.put(key, value);
}
return returnResult;
}
分页查询
public static List<Map<String, String>> listCommunityByPage(String tableName, long pageNum, long pageSize) throws IOException {
List<Map<String, String>> returnResult = new ArrayList<>();
try {
Table table = connection.getTable(TableName.valueOf(tableName));
long skip = pageSize * (pageNum - 1);
String preRowKey = null;
boolean stop = false;
while (skip > 0 && !stop) {
long step = 0;
if (skip >= 1000) {
step = 1000;
} else {
step = skip;
}
skip -= step;
Filter pageFilter = new PageFilter(step + 1);
Filter kof = new KeyOnlyFilter();
List<Filter> filters = new ArrayList<Filter>();
filters.add(pageFilter);
filters.add(kof);
FilterList fl = new FilterList(FilterList.Operator.MUST_PASS_ALL, filters);
Scan scan = new Scan();
scan.setFilter(fl);
if (!StringUtils.isBlank(preRowKey)) {
scan.setStartRow(preRowKey.getBytes());
}
ResultScanner rs = table.getScanner(scan);
long count = 0;
long endIndex = step + 1;
for (Result result : rs) {
count++;
if (count == endIndex) {
preRowKey = new String(result.getRow());
}
}
if (count < endIndex) {
stop = true;
}
}
if (stop == true) {
return returnResult;
}
Filter pageFilter = new PageFilter(pageSize);
Scan scan = new Scan();
scan.setFilter(pageFilter);
if (!StringUtils.isBlank(preRowKey)) {
scan.setStartRow(preRowKey.getBytes());
}
ResultScanner rs = table.getScanner(scan);
for (Result result : rs) {
Map<String, String> item = new HashMap<>();
String row = new String(result.getRow());
item.put(Constants.hbaseRowKey, row);
List<Cell> listCells = result.listCells();
for (Cell cell : listCells) {
String key = new String(cell.getQualifierArray(), cell.getQualifierOffset(), cell
.getQualifierLength());
String value = new String(cell.getValueArray(), cell.getValueOffset(), cell
.getValueLength());
if (StringUtils.isBlank(key) || StringUtils.isBlank(value)) {
continue;
}
if (key.matches("^pre\\d+_")) {
key = key.substring(key.indexOf("_") + 1);
}
item.put(key, value);
}
returnResult.add(item);
}
} catch (IOException e) {
e.printStackTrace();
}
return returnResult;
}
注意到上述有一个常量：
public class Constants {
public static String hbaseRowKey = "_row_id";
}
标签： cell、returnresult、scan、listcells、string
