这个自定义的Comparator也是看了好多资料，总结一下全部流程，（还是csdn 1800+的阅读给了我动力，重新弄了一遍，很顺利）。
使用场景描述下，hbase列值比较器是采用alpha字母表进行比较的这就导致想要对某些列进行数值过滤比较坑，比如2.0会比100大。 该CustomNumberComparator需要结合过滤器进行使用，本项目结合SingleColumnValueFilter进行列值过滤，其他过滤器没有测试。
此处是基于cdh-hbase1.2.0 分享自定义hbase filter全过程(此处的Comparator是针对SingleColumnFilter进行测试的,其他的过滤器并没具体测试)。
1.制作 CustomComparatorProtos.proto文件
先编辑一个文件命名为CustomComparatorProtos.proto 具体内容如下：
/**
- Licensed to the Apache Software Foundation (ASF) under one
- or more contributor license agreements. See the NOTICE file
- distributed with this work for additional information
- regarding copyright ownership. The ASF licenses this file
- to you under the Apache License, Version 2.0 (the
- "License"); you may not use this file except in compliance
- with the License. You may obtain a copy of the License at
- http://www.apache.org/licenses/LICENSE-2.0
- Unless required by applicable law or agreed to in writing, software
- distributed under the License is distributed on an "AS IS" BASIS,
- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- See the License for the specific language governing permissions and
- limitations under the License. */
// This file contains protocol buffers that are used for filters
option java_package = "com.pateo.hbase.defined.comparator"; option java_outer_classname = "MyComparatorProtos"; option java_generic_services = true; option java_generate_equals_and_hash = true; option optimize_for = SPEED;
// This file contains protocol buffers that are used for comparators (e.g. in filters)
message CustomNumberComparator { required bytes value = 1; required string fieldType = 2; }
使用protoc编辑器进行编译 在protoc 当前的目录 打开终端进入当前目录执行 CMD 执行如下命令 ： protoc –java_out=D:\proto CustomNumberComparator.proto 然后得到MyComparatorProtos.java
创建package和上面的填写额一致（com.pateo.hbase.defined.comparator），将MyComparatorProtos.java导入自己定义的package下面， 并且在该package下面创建CustomNumberComparator.java继承ByteArrayComparable 。
//具体代码 参考该package下的com.pateo.hbase.defined.comparator.CustomNumberComparator源文件，此处省略。
4.选中这两个java文件右击export 输出为jar文件
上传到hbase的lib目录下面，比如 CDH集群的话copy到/data/cloudera/parcels/CDH-5.12.0-1.cdh5.12.0.p0.29/lib/hbase/lib目录下面
重启hbase
在hbase shell中引入以下 java包
import org.apache.hadoop.hbase.filter.CompareFilter import org.apache.hadoop.hbase.filter.SingleColumnValueFilter import com.pateo.hbase.defined.comparator.CustomNumberComparator import com.pateo.hbase.defined.comparator.MyComparatorProtos
scan 'student',{COLUMNS =>'score:chinese',FILTER=>SingleColumnValueFilter.new(Bytes.toBytes('score'),Bytes.toBytes('chinese'),CompareFilter::CompareOp.valueOf('GREATER'),CustomNumberComparator.new(Bytes.toBytes(2.0),"double"))}
- java 代码测试参考 test.TestHbaseJava
注意事项：列值为'', ' ' '+' 等会导致filter失败，应该是数值转换失败导致的,可以考虑在CustomNumberComparator得compare方法中，进行相应的处理，避免parse value出错。