UDF函数：根据日期生日等查询星座

    自定义UDF函数实现：根据用户的生日，判断用户是什么星座.

import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDF;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.joda.time.DateTime;
import org.joda.time.format.DateTimeFormat;
import org.joda.time.format.DateTimeFormatter;

import java.util.Date;

/**
 * 此函数实现用户输入字符串格式为yyyy-MM-dd形式的日期，返回该用户的星座类型
 */
@Description(name = "zodiac_cn"
        , value = "_FUNC_(date) - from the input date string or separate month and day arguments, returns the sing of the Zodiac."
        , extended = "Example:\n > select _FUNC_(date_string) from src;\n > select _FUNC_(month, day) from src;")
public class UDFZodiacSignCn extends UDF {
    //日期的输入格式固定为:yyyy-MM-dd
	public final static DateTimeFormatter DEFAULT_DATE_FORMATTER = DateTimeFormat.forPattern("yyyy-MM-dd");
   
    private Text result = new Text();

    public UDFZodiacSignCn() {
    }

    public Text evaluate(Text birthday) {
        DateTime dateTime = null;
        try {
            dateTime = DateTime.parse(birthday.toString(), DEFAULT_DATE_FORMATTER);
        } catch (Exception e) {
            return null;
        }

        return evaluate(dateTime.toDate());
    }

    public Text evaluate(Date birthday) {
        DateTime dateTime = new DateTime(birthday);
        return evaluate(new IntWritable(dateTime.getMonthOfYear()), new IntWritable(dateTime.getDayOfMonth()));
    }

    public Text evaluate(IntWritable month, IntWritable day) {
        result.set(getZodiac(month.get(), day.get()));
        return result;
    }

    private String getZodiac(int month, int day) {
        String[] zodiacArray = {"魔羯座", "水瓶座", "双鱼座", "白羊座", "金牛座", "双子座", "巨蟹座", "狮子座", 
                                 "处女座", "天秤座", "天蝎座", "射手座"};
        int[] splitDay = {19, 18, 20, 20, 20, 21, 22, 22, 22, 22, 21, 21}; // 两个星座分割日
        int index = month;
        // 所查询日期在分割日之前，索引-1，否则不变
        if (day <= splitDay[month - 1]) {
            index = index - 1;
        } else if (month == 12) {
            index = 0;
        }
        // 返回索引指向的星座string
        return zodiacArray[index];
    }
    
    public static void main(String[] args) {
		UDFZodiacSignCn udfZodiacSignCn = new UDFZodiacSignCn();
		System.out.println("1990-11-02:     "+udfZodiacSignCn.evaluate(new Text("1990-11-02")));
		//错误格式的日期，返回值为null
		System.out.println(udfZodiacSignCn.evaluate(new Text("19901102")));
		System.out.println("2000-11-02:     "+udfZodiacSignCn.evaluate(new Text("2000-11-02")));
		System.out.println("2000-01-02:     "+udfZodiacSignCn.evaluate(new Text("2000-01-02")));
		
	}
}

测试结果显示：
1990-11-02:     天蝎座
null
2000-11-02:     天蝎座
2000-01-02:     魔羯座