hbase简介
HBase是一个分布式的、面向列的开源数据库，该技术来源于 Fay Chang 所撰写的Google论文“Bigtable：一个结构化数据的分布式存储系统”。就像Bigtable利用了Google文件系统（File System）所提供的分布式数据存储一样，HBase在Hadoop之上提供了类似于Bigtable的能力。HBase是Apache的Hadoop项目的子项目。HBase不同于一般的关系数据库，它是一个适合于非结构化数据存储的数据库。另一个不同的是HBase基于列的而不是基于行的模式。
hbase表结构
表
列簇1 列簇2（建议1-3个列簇）
列a 列b... 列a 列b...
列簇会用于做索引，一般列簇1,2用于存放常用的筛选用字段，列簇3用于存放内容字段
在下面的代码示例中，一共有两个列簇，familyName1和familyName2
familyName1中存放了三个用于频繁查询筛选的字段：ab，dt，hb
familyName2中存放了整个数据结构的json化字符串
hbase操作 代码示例
1、创建表
2、增/改
public void put(String tableName, Object item) {
if (item== null) {
LOG.error("[HBase] itemis null!");
return;
}
// 设置rowkey
if (item.getid() == null || item.getid().isEmpty()) {
LOG.error("[HBase] Adding null/empty key!");
return;
}
String ultimateRowKey = getHashedID(item.getid());
if (ultimateRowKey == null || ultimateRowKey.isEmpty()) {
LOG.error("[HBase] Adding null/empty hashed key! Original key is " + item.getid());
return;
}
Put put = new Put(Bytes.toBytes(ultimateRowKey));
// HTabel负责跟记录相关的操作如增删改查等
Table table = null;
try {
table = con.getTable(TableName.valueOf(tableName));
put.addColumn(Bytes.toBytes(familyName1), Bytes.toBytes("ab"), Bytes.toBytes(item.getAvailable()));
put.addColumn(Bytes.toBytes(familyName1), Bytes.toBytes("dt"), Bytes.toBytes(item.getDistype()));
put.addColumn(Bytes.toBytes(familyName1), Bytes.toBytes("hb"), Bytes.toBytes(item.getHotboost()));
Gson gson = new Gson();
String value = gson.toJson(item);
put.addColumn(Bytes.toBytes(familyName2), Bytes.toBytes("js"), Bytes.toBytes(value));
table.put(put);
} catch (IOException e) {
LOG.error("[HBase] Failed to connect to table while adding! " + e.getMessage());
} finally {
try {
if (table != null)
table.close();
} catch (IOException e) {
LOG.error("[HBase] Error while closing table " + e.getMessage());
}
}
}
3、删
//按照rowkey进行删除某一行
public void del(String tablename, String rowkey) {
// 设置rowkey
if (rowkey == null || rowkey.isEmpty()) {
LOG.error("[HBase] Adding null/empty key!");
return;
}
String ultimateRowKey = getHashedID(rowkey);
if (ultimateRowKey == null || ultimateRowKey.isEmpty()) {
LOG.error("[HBase] Adding null/empty hashed key! Original key is " + rowkey);
return;
}
Table table = null;
Delete delete = new Delete(Bytes.toBytes(ultimateRowKey));
try {
table = con.getTable(TableName.valueOf(tablename));
table.delete(delete);
} catch (IOException e) {
LOG.error("[HBase] Failed to connect to table while del! " + e.getMessage());
} finally {
try {
if (table != null)
table.close();
} catch (IOException e) {
LOG.error("[HBase] Error while closing table " + e.getMessage());
}
}
}
4、查
public String get(String tablename, String rowKey) {
// 先查询索引表
Table cntTable = null;
try {
cntTable = con.getTable(TableName.valueOf(tablename));
String ultimateRowKey = getHashedID(rowKey);
if (ultimateRowKey == null || ultimateRowKey.isEmpty()) {
LOG.error("[HBase] Getting hashed null/empty key! Original key is " + rowKey);
return null;
}
Get get = new Get(Bytes.toBytes(ultimateRowKey));
Result result = cntTable.get(get);
String hbaseValue = Bytes.toString(result.getValue(Bytes.toBytes(familyName2), Bytes.toBytes("js")));
return hbaseValue;
} catch (IOException e) {
LOG.error("[HBase] Failed to connect to " + tablename + " while getting! " + e.getMessage());
return null;
} finally {
try {
if (cntTable != null)
cntTable.close();
} catch (IOException e) {
LOG.error("[HBase] Error while closing table " + tablename + e.getMessage());
}
}
}
5、批量写入
public <T> void puts(String tableName, Map<String, Object> items) {
if (items == null || items.isEmpty()) {
LOG.error("[HBase] Adding null/empty item map!");
return;
}
int maxSize = 10000;
Table table = null;
try {
table = con.getTable(TableName.valueOf(tableName));
int eachSize = Math.min(maxSize, items.size());
List<Put> puts = new ArrayList<Put>(eachSize);
int handled = 0;
for (Entry<String, Object> entry : items.entrySet()) {
String ultimateRowKey = getHashedID(entry.getKey());
Object value = entry.getValue();
if (ultimateRowKey == null || ultimateRowKey.isEmpty()) {
LOG.error("[HBase] Adding null/empty hashed key! Original key is " + entry.getKey());
handled++;
continue;
}
// System.out.println(ultimateRowKey);
Put put = new Put(Bytes.toBytes(ultimateRowKey));
put.addColumn(Bytes.toBytes(familyName1), Bytes.toBytes("ab"), Bytes.toBytes(value .getAb()));
put.addColumn(Bytes.toBytes(familyName1), Bytes.toBytes("dt"), Bytes.toBytes(value .getDt()));
put.addColumn(Bytes.toBytes(familyName1), Bytes.toBytes("hb"), Bytes.toBytes(value .getHb()));
Gson gson = new Gson();
String valuestr = gson.toJson(value);
put.addColumn(Bytes.toBytes(familyName2), Bytes.toBytes("js"), Bytes.toBytes(valuestr));
puts.add(put);
handled++;
// 每隔10000,写一次
if (handled == eachSize) {
LOG.info("[HBase] Adding " + eachSize + "rows!");
table.put(puts);
puts = new ArrayList<Put>(eachSize);
}
}
if (puts.size() > 0)
table.put(puts);
} catch (IOException e) {
LOG.error("[HBase] Error while putting data " + e.getMessage());
} finally {
try {
if (table != null)
table.close();
} catch (IOException e) {
LOG.error("[HBase] Error while closing table " + e.getMessage());
}
}
}
