Query String is part of the URL, used to pass the extra information to the request.
Ex
http://example.com/employee?name=devi&city=Ongole
Below snippet converts the query string to a map.
private static MapString, String> parseQueryString(String queryString) throws UnsupportedEncodingException {
if (queryString == null || queryString.isEmpty()) {
return Collections.EMPTY_MAP;
}
String[] queryParams = queryString.split("&");
MapString, String> map = new HashMap();
for (String queryParam : queryParams) {
int index = queryParam.indexOf('=');
String key = queryParam.substring(0, index);
key = URLDecoder.decode(key, "UTF-8");
String value = null;
if (index > 0) {
value = queryParam.substring(index + 1);
value = URLDecoder.decode(value, "UTF-8");
}
map.put(key, value);
}
return map;
}
Find the below working application.
Test.java
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
public class Test {
private static MapString, String> parseQueryString(String queryString) throws UnsupportedEncodingException {
if (queryString == null || queryString.isEmpty()) {
return Collections.emptyMap();
}
String[] queryParams = queryString.split("&");
MapString, String> map = new HashMap();
for (String queryParam : queryParams) {
int index = queryParam.indexOf('=');
String key = queryParam.substring(0, index);
key = URLDecoder.decode(key, "UTF-8");
String value = null;
if (index > 0) {
value = queryParam.substring(index + 1);
value = URLDecoder.decode(value, "UTF-8");
}
map.put(key, value);
}
return map;
}
private static void printMap(MapString, String> map) {
SetMap.EntryString, String>> entrySet = map.entrySet();
for (Map.EntryString, String> entry : entrySet) {
System.out.println(entry.getKey() + " : " + entry.getValue());
}
}
private static void parseAndPrintQueryString(String queryString) throws UnsupportedEncodingException {
MapString, String> map = parseQueryString(queryString);
System.out.println("\nFor the query String : " + queryString);
printMap(map);
}
public static void main(String args[]) throws IOException, ClassNotFoundException {
String queryString1 = "name=devi&city=Ongole";
String queryString2 = "name=&city=Ongole";
String queryString3 = "name=devi&city=";
String queryString4 = "name=&city=";
parseAndPrintQueryString(queryString1);
parseAndPrintQueryString(queryString2);
parseAndPrintQueryString(queryString3);
parseAndPrintQueryString(queryString4);
}
}
Output
For the query String : name=devi&city=Ongole
city : Ongole
name : devi
For the query String : name=&city=Ongole
city : Ongole
name :
For the query String : name=devi&city=
city :
name : devi
For the query String : name=&city=
city :
name :
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