disable ‘users‘
alter ‘users‘, METHOD => ‘table_att‘, ‘coprocessor‘=>‘file:///home/u/mylib/UsersObserver.jar|test.hbase.inaction.example5_2.UsersObserver|1001|‘
alter ‘users‘, METHOD => ‘table_att_unset‘,NAME => ‘coprocessor$2‘
删除
enable ‘users‘
hbase(main):022:0> scan ‘users‘
ROW COLUMN+CELL
id01 column=info:email, timestamp=1413963413002, value=wyj@gmail.com
id01 column=info:name, timestamp=1413963413002, value=wyj
id01 column=info:password, timestamp=1413963413002, value=000000
id01 column=info:user, timestamp=1413963413002, value=id01
id09 column=info:email, timestamp=1414566775616, value=test9@gmail.com
id09 column=info:name, timestamp=1414566775616, value=test9
id09 column=info:password, timestamp=1414566775616, value=9
id09 column=info:user, timestamp=1414566775616, value=id09
id99 column=info:email, timestamp=1414565339530, value=test99@gmail.com
id99 column=info:name, timestamp=1414565339530, value=test99
id99 column=info:password, timestamp=1414565339530, value======01=====
id99 column=info:user, timestamp=1414565339530, value=id99
invalID column=info:invalid_pass, timestamp=1414566775657, value=invalid_pass:9
11 row(s) in 0.1290 seconds
start() 和stop()这两个方法，在表enable和disable时分别也会对应执行
这start()和stop()在连接池里获得连接与释放连接实在是多余
observer类似触发器，操作一张表的时候要注意递归调用，拦截到一次put后再put这个表就会递归
这个例子就是这样的，实际上没任何意义，就是个例子而已
注意锁，HBase是行级的锁，如果想put同一行是不会成功的
observer很不好调试，只能整一堆的log......
package test.hbase.inaction.example5_2;
import java.io.IOException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.CoprocessorEnvironment;
import org.apache.hadoop.hbase.client.HTableInterface;
import org.apache.hadoop.hbase.client.HTablePool;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.coprocessor.BaseRegionObserver;
import org.apache.hadoop.hbase.coprocessor.ObserverContext;
import org.apache.hadoop.hbase.coprocessor.RegionCoprocessorEnvironment;
import org.apache.hadoop.hbase.regionserver.wal.WALEdit;
import org.apache.hadoop.hbase.util.Bytes;
import test.hbase.inaction.example2_4.User;
import test.hbase.inaction.example2_4.UsersDAO;
/*
<span style="color:#ff0000;">先disable表，然后alert一下，那个1001是优先级，别忘记enable</span>
disable 'users'
alter 'users', METHOD => 'table_att', 'coprocessor'=>'file:///home/u/mylib/FollowsObserver.jar|test.hbase.inaction.example5_2.FollowsObserver|1001|'
alter 'users', METHOD => 'table_att_unset',NAME => 'coprocessor$2'<span style="white-space:pre"> </span>
enable 'users'
describe 'users'
*/
public class UsersObserver extends BaseRegionObserver {
private final Log log = LogFactory.getLog(this.getClass());
private HTablePool pool = null;
public void start(CoprocessorEnvironment env) throws IOException {
log.info("WYJ ---------------------------- start() begin");
pool = new HTablePool(env.getConfiguration(), Integer.MAX_VALUE);
log.info("pool=" + pool);
log.info("WYJ ---------------------------- start() end");
}
public void stop(CoprocessorEnvironment env) throws IOException {
log.info("WYJ ---------------------------- stop() begin");
pool.close();
log.info("WYJ ---------------------------- stop() end");
}
public void postPut(final ObserverContext<RegionCoprocessorEnvironment> e,
final Put put, final WALEdit edit, final boolean writeToWAL) {
log.info("WYJ: ================================================ postPut() begin");
try {
byte[] table = e.getEnvironment().getRegion().getRegionInfo()
.getTableName();
log.info("table=" + Bytes.toString(table));
if (!Bytes.equals(table, UsersDAO.TABLE_NAME)) {
return;
}
String pass = Bytes.toString(put.get(UsersDAO.INFO_FAM, UsersDAO.PASS_COL).get(0).getValue());
log.info("pass=" + pass);
byte[] user = put.get(UsersDAO.INFO_FAM, UsersDAO.USER_COL).get(0).getValue();
log.info("user=" + Bytes.toString(user));
if (pass == null || pass.length() < 6) {
log.info("password.length=" + pass.length());
UsersDAO dao = new UsersDAO(pool);
log.info("pool=" + pool);
dao.addUser("id99", "test99", "test99@gmail.com", "=====01=====");
log.info("dao.addUser(\"id99\", \"test99\", \"test99@gmail.com\", \"99999999\"); FINAL");
}
} catch (Exception ex) {
log.error(ex, ex);
}
log.info("WYJ: ================================================ postPut() end");
}
}
原文地址：http://blog.csdn.net/lebronjames/article/details/40617265
