Hive創建UDTF函數

Hive創建UDTF函數

這部分不知道建一個什麼樣的函數，就照着網上的來了，所以就不寫其他東西了

package com.chinasofti.hive.udf;

import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.exec.UDFArgumentLengthException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDTF;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.StructObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;

import java.util.ArrayList;

// 繼承 GenericUDTF 類，需要實現 process 和 close 方法，然後還需要自己重寫 initialize 方法
public class TestUDTF extends GenericUDTF {

    //
    @Override
    public StructObjectInspector initialize(ObjectInspector[] args)
            throws UDFArgumentException {
        if (args.length != 1) {
            throw new UDFArgumentLengthException("ExplodeMap takes only one argument");
        }
        if (args[0].getCategory() != ObjectInspector.Category.PRIMITIVE) {
            throw new UDFArgumentException("ExplodeMap takes string as a parameter");
        }

        ArrayList<String> fieldNames = new ArrayList<String>();
        ArrayList<ObjectInspector> fieldOIs = new ArrayList<ObjectInspector>();
        fieldNames.add("col1");
        fieldOIs.add(PrimitiveObjectInspectorFactory.javaStringObjectInspector);
        fieldNames.add("col2");
        fieldOIs.add(PrimitiveObjectInspectorFactory.javaStringObjectInspector);

        return ObjectInspectorFactory.getStandardStructObjectInspector(fieldNames,fieldOIs);
    }

    public void process(Object[] args) throws HiveException {
        String input = args[0].toString();
        String[] test = input.split(";");
        for(int i=0; i<test.length; i++) {
            try {
                String[] result = test[i].split(":");
                forward(result);
            } catch (Exception e) {
                continue;
            }
        }
    }

    public void close() throws HiveException {

    }
}

參考：

Hive API

hive-2 自定義函數UDF、UDAF、UDTF介紹及區別