Hive 基于GenericUDF创建UDF

package com.am.udf;

import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDF;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.StringObjectInspector;


public class IpUDFOversea  extends GenericUDF {
    private transient StringObjectInspector stringOI;
    private transient DatabaseReader reader ;

    @Override
    public ObjectInspector initialize(ObjectInspector[] args) throws UDFArgumentException {
        if (args.length != 1) {
            throw new UDFArgumentException("IpUDFOversea() takes  only one argument");
        }

        if (args[0].getCategory() != ObjectInspector.Category.PRIMITIVE
                && ((PrimitiveObjectInspector) args[0]).getPrimitiveCategory() != PrimitiveObjectInspector.PrimitiveCategory.STRING) {
            throw new UDFArgumentException("IpUDFOversea() takes a String as a parameter");
        }

        System.out.println(args[0]);
        this.stringOI = (StringObjectInspector) args[0];

        return PrimitiveObjectInspectorFactory.javaStringObjectInspector;
    }

    @Override
    public Object evaluate(DeferredObject[] args) throws HiveException {
        String ip = stringOI.getPrimitiveJavaObject(args[0].get());
        if(null == ip) {
            return null;
        }
        // do Ip 解析


        return JSONObject.toJSONString(map);
    }

    @Override
    public String getDisplayString(String[] children) {
        StringBuilder sb = new StringBuilder();
        sb.append("input ip ");
        sb.append(children[0]);
        return sb.toString();
    }
}