Parse String to get grouped parameters

Question

My String looks like this

http://localhost:8080/HospitalServer/files/file?id=34&firstname=alex&lastname=ozouf&age=33&firstname=kevin&lastname=gerfild&age=27

I use this code to parse the parameters

final Map<String, List<String>> query_pairs = new LinkedHashMap<String, List<String>>();
          final String[] pairs = query.split("&");
          for (String pair : pairs) {
            final int idx = pair.indexOf("=");
            final String key = idx > 0 ? URLDecoder.decode(pair.substring(0, idx), "UTF-8") : pair;
            if (!query_pairs.containsKey(key)) {
              query_pairs.put(key, new LinkedList<String>());
            }
            final String value = idx > 0 && pair.length() > idx + 1 ? URLDecoder.decode(pair.substring(idx + 1), "UTF-8") : null;
            query_pairs.get(key).add(value);

          }
          System.out.println(query_pairs);

The result is

{id=[34], firstname=[alex, kevin], lastname=[ozouf, gerfild], age=[33, 27]}

The result is not too bad but I want to group the parameters by person.

{id=[34], 1=[alex,ozouf,33 ], 2=[kevin, gerfild,27]}

I can create it from the previous result but I have the feeling that the job is done twice. What do you think I shall do ?

Why not use `String[] getRequestParameterValues("firstname")` and so on then create an array of `Person` or such. Or is it not JavaEE? — Joop Eggen, Apr 26 '16 at 15:54
I would remove the tag "javaparser", as this question is not related to https://github.com/javaparser/javaparser — Federico Tomassetti, Apr 26 '16 at 16:22

score 1 · Answer 1 · answered Aug 20 '18 at 23:03

Here's how you can do it without using any library:

import java.util.Map;
import java.util.HashMap;

public class MyUrlParser {

  private static final String SEPARATOR = ",";

  public static void main(String[] args) {
    final String URL = "http://localhost:8080/HospitalServer/files/file?id=34&firstname=alex&lastname=ozouf&age=33&firstname=kevin&lastname=gerfild&age=27";

    MyUrlParser mup = new MyUrlParser();
    try {
      Map<String, String> parsed = mup.parse(URL);
      System.out.println(parsed);
    } catch (Exception e) {
      System.err.println(e.getMessage());
    }
  }

  public Map<String, String> parse(String url) throws Exception {
    Map<String, String> retMap = new HashMap<>();
    int queryStringPos = url.indexOf("?");
    if (-1 == queryStringPos) {
      throw new Exception("Invalid URL");
    }
    String queryString = url.substring(queryStringPos + 1);
    String[] parameters = queryString.split("&");
    if (parameters.length > 0) {
      retMap.put("id", parameters[0]);
      int personCounter = 0;
      for (int minSize = 4; minSize <= parameters.length; minSize += 3) {
         StringBuilder person = new StringBuilder();
         person.append(parameters[minSize-3]);
         person.append(SEPARATOR);
         person.append(parameters[minSize-2]);
         person.append(SEPARATOR);
         person.append(parameters[minSize-1]);
         personCounter++;
         retMap.put("person" + personCounter, person.toString());
      }
    }
    return retMap;
  }
}

Parse String to get grouped parameters

1 Answers1