UDF函数 解码url

背景

URL 的编码 是ASCII十六进制格式。数仓接受到前端上报的URL，要对URL字段解码。

如要将

https%3A%2F%2Fmywebsite%2Fdocs%2Fenglish%2Fsite%2"Fmybook.do%3Frequest_type%3D%26type%3Dprivate

解码为:

https://mywebsite/docs/english/site/mybook.do?request_type=&type=private

方式

hive sql中，通过反射调用java.net.URLDecoder方法

select reflect('java.net.URLDecoder', 'decode',url, 'UTF-8') from table_name;

问题

实践中发现，部分https开头的url解析不完整。例如解码下面的URL，

https%253A%252F%252Fwww.cnblogs.com/drjava

通过上面的方法，结果是：

https%3A%2F%2Fwww.cnblogs.com/drjava

解决方案

通过google找到了可行的方法，解码两次，由于sql写起来比较难以阅读，所以封装了udf。代码如下：

 import org.apache.hadoop.hive.ql.exec.UDF;
 import java.io.UnsupportedEncodingException;
 import java.net.URLDecoder;

 public class UrlDecode extends UDF {
     /**
      *
      *
      * @param component 编码的url
      * @return 解码url
      */
     public  String evaluate(String component) {
         if(component == null || component.length() <= 0){
             return "";
         }

         String result = "";
         component = component.replaceAll("%(?![0-9a-fA-F]{2})", "%25");
         try {
             result = URLDecoder.decode(component, "UTF-8");
             result = URLDecoder.decode(result, "UTF-8");
         } catch (UnsupportedEncodingException e) {
             result = component;
         }
         return result;
     }
 }

做一下单元测试

 import org.junit.Assert;
 import org.junit.Test;
 import udf.UrlDecode;

 public class UrlDecodeTest {
     @Test
     public void UrlDecodeMethod(){
         UrlDecode ud = new UrlDecode();
         Assert.assertEquals(ud.evaluate("https%3A%2F%2Fmywebsite%2Fdocs%2Fenglish%2Fsite%2" +
                 "Fmybook.do%3Frequest_type%3D%26type%3Dprivate"),
                 "https://mywebsite/docs/english/site/mybook.do?request_type=&type=private");

         Assert.assertEquals(ud.evaluate("你是谁，为了谁"),"你是谁，为了谁");

         Assert.assertEquals(ud.evaluate(null),"");
     }
 }