hive添加UDF
步骤如下：
-
函数分为永久和临时函数，后者会话退出则消失，前者不会
-
查看已有函数（创建好后也可以通过这个来查看是否成功）
show functions;
- 写UDF的java文件，如：
/**
* 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.
*/
package org.apache.hadoop.hive.ql.udf;
import org.apache.hadoop.hive.ql.exec.UDF;
import org.apache.hadoop.hive.serde2.ByteStream;
import org.apache.hadoop.hive.serde2.io.ByteWritable;
import org.apache.hadoop.hive.serde2.io.DoubleWritable;
import org.apache.hadoop.hive.serde2.io.ShortWritable;
import org.apache.hadoop.hive.serde2.io.TimestampWritable;
import org.apache.hadoop.hive.serde2.lazy.LazyInteger;
import org.apache.hadoop.hive.serde2.lazy.LazyLong;
import org.apache.hadoop.io.BooleanWritable;
import org.apache.hadoop.io.BytesWritable;
import org.apache.hadoop.io.FloatWritable;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
/**
* UDFToString.
*
*/
public class UDFToString extends UDF {
private final Text t = new Text();
private final ByteStream.Output out = new ByteStream.Output();
public UDFToString() {
}
public Text evaluate(NullWritable i) {
return null;
}
private final byte[] trueBytes = {'T', 'R', 'U', 'E'};
private final byte[] falseBytes = {'F', 'A', 'L', 'S', 'E'};
public Text evaluate(BooleanWritable i) {
if (i == null) {
return null;
} else {
t.clear();
t.set(i.get() ? trueBytes : falseBytes);
return t;
}
}
public Text evaluate(ByteWritable i) {
if (i == null) {
return null;
} else {
out.reset();
LazyInteger.writeUTF8NoException(out, i.get());
t.set(out.getData(), 0, out.getCount());
return t;
}
}
public Text evaluate(ShortWritable i) {
if (i == null) {
return null;
} else {
out.reset();
LazyInteger.writeUTF8NoException(out, i.get());
t.set(out.getData(), 0, out.getCount());
return t;
}
}
public Text evaluate(IntWritable i) {
if (i == null) {
return null;
} else {
out.reset();
LazyInteger.writeUTF8NoException(out, i.get());
t.set(out.getData(), 0, out.getCount());
return t;
}
}
public Text evaluate(LongWritable i) {
if (i == null) {
return null;
} else {
out.reset();
LazyLong.writeUTF8NoException(out, i.get());
t.set(out.getData(), 0, out.getCount());
return t;
}
}
public Text evaluate(FloatWritable i) {
if (i == null) {
return null;
} else {
t.set(i.toString());
return t;
}
}
public Text evaluate(DoubleWritable i) {
if (i == null) {
return null;
} else {
t.set(i.toString());
return t;
}
}
public Text evaluate(Text i) {
if (i == null) {
return null;
}
i.set(i.toString());
return i;
}
public Text evaluate(TimestampWritable i) {
if (i == null) {
return null;
} else {
t.set(i.toString());
return t;
}
}
public Text evaluate (BytesWritable bw) {
if (null == bw) {
return null;
}
t.set(bw.getBytes(),0,bw.getLength());
return t;
}
}
- 将写好的java文件打包成jar：
jar cvf UDFUpper.jar -c bin UDFUpper.java
- 进入hive，添加jar文件
hive> add jar UDFToString.jar;
Added [UDFToString.jar] to class path
Added resources: [UDFToString.jar]
-
添加临时函数（会话结束函数消失）
-
进入hive，添加jar文件
hive> add jar UDFToString.jar; Added [UDFToString.jar] to class path Added resources: [UDFToString.jar] -
添加函数(注意class所在包)
语法为： CREATE TEMPORARY FUNCTION function_name AS class_name; hive> create temporary function mytest as 'org.apache.hadoop.hive.ql.udf.UDFToString'; OK Time taken: 0.009 seconds 路径出错会提示： FAILED: Class default.udf.Upper not found FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.FunctionTask 具体类路径为UDF java文件里的package+'.'+java文件名 -
删除临时函数
DROP TEMPORARY FUNCTION [IF EXISTS] function_name;
-
-
添加永久函数
-
添加
语法： CREATE FUNCTION [db_name.]function_name AS class_name [USING JAR|FILE|ARCHIVE 'file_uri' [, JAR|FILE|ARCHIVE 'file_uri'] ]; 注意： 如果hive非本地模式运行，则后面应该是为非本地文件等URI，如hdfs路径，否则会报错； 例子： hive> create function default.hah as "org.apache.hadoop.hive.ql.udf.UDFToString" using jar "UDFToString.jar"; FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.FunctionTask. Hive warehouse is non-local, but UDFToString.jar specifies file on local filesystem. Resources on non-local warehouse should specify a non-local scheme/path hive> create function default.hah as "org.apache.hadoop.hive.ql.udf.UDFToString" using jar "hdfs:///hdfs_home/UDFToString.jar"; converting to local hdfs:///hdfs_home/UDFToString.jar Added [/tmp/fda83e6d-e1af-4005-affa-9f9c4ee226a6_resources/UDFToString.jar] to class path Added resources: [hdfs:///hdfs_home/UDFToString.jar] OK Time taken: 0.521 seconds -
删除
DROP FUNCTION [IF EXISTS] function_name;
-
引用第三方包的情况
假如在你的UDF文件里引用了第三方包，那么只需要在生成jar文件的时候改变一下命令就可以了，如下：
javac -classpath hive-0.4.1.jar:commons-io-2.5.jar:bcprov-jdk15on-158.jar com/example/hive/udf/UDFDecrypt.java
jar -cvf UDFDecrypt.jar ./com/example/hive/udf/UDFDecrypt.class
上面javac命令中classpath跟的是用到的第三方包名，使用：做间隔，后面跟的是java文件路径
此处参考了这里