Parsing query strings on Android

user_15721 0
Viewed 172251

Java EE has ServletRequest.getParameterValues().

On non-EE platforms, URL.getQuery() simply returns a string.

What's the normal way to properly parse the query string in a URL when not on Java EE?

It is popular in the answers to try and make your own parser. This is very interesting and exciting micro-coding project, but I cannot say that it is a good idea.

The code snippets below are generally flawed or broken. Breaking them is an interesting exercise for the reader. And to the hackers attacking the websites that use them.

Parsing query strings is a well defined problem but reading the spec and understanding the nuances is non-trivial. It is far better to let some platform library coder do the hard work, and do the fixing, for you!

url android parsing java
25 Answers

On Android its simple as the code below:

UrlQuerySanitizer sanitzer = new UrlQuerySanitizer(url);
String value = sanitzer.getValue("your_get_parameter");

Also if you don't want to register each expected query key use:

sanitzer.setAllowUnregisteredParamaters(true)

Before calling:

sanitzer.parseUrl(yourUrl)
user_26887550

On Android, you can use the Uri.parse static method of the android.net.Uri class to do the heavy lifting. If you're doing anything with URIs and Intents you'll want to use it anyways.

user_1058800

Guava's Multimap is better suited for this. Here is a short clean version:

Multimap<String, String> getUrlParameters(String url) {
        try {
            Multimap<String, String> ret = ArrayListMultimap.create();
            for (NameValuePair param : URLEncodedUtils.parse(new URI(url), "UTF-8")) {
                ret.put(param.getName(), param.getValue());
            }
            return ret;
        } catch (URISyntaxException e) {
            throw new RuntimeException(e);
        }
    }
user_4711360

Origanally answered here

On Android, there is Uri class in package android.net . Note that Uri is part of android.net, while URI is part of java.net .

Uri class has many functions to extract query key-value pairs. enter image description here

Following function returns key-value pairs in the form of HashMap.

In Java:

Map<String, String> getQueryKeyValueMap(Uri uri){
    HashMap<String, String> keyValueMap = new HashMap();
    String key;
    String value;

    Set<String> keyNamesList = uri.getQueryParameterNames();
    Iterator iterator = keyNamesList.iterator();

    while (iterator.hasNext()){
        key = (String) iterator.next();
        value = uri.getQueryParameter(key);
        keyValueMap.put(key, value);
    }
    return keyValueMap;
}

In Kotlin:

fun getQueryKeyValueMap(uri: Uri): HashMap<String, String> {
        val keyValueMap = HashMap<String, String>()
        var key: String
        var value: String

        val keyNamesList = uri.queryParameterNames
        val iterator = keyNamesList.iterator()

        while (iterator.hasNext()) {
            key = iterator.next() as String
            value = uri.getQueryParameter(key) as String
            keyValueMap.put(key, value)
        }
        return keyValueMap
    }
user_89560930 
if (queryString != null)
{
    final String[] arrParameters = queryString.split("&");
    for (final String tempParameterString : arrParameters)
    {
        final String[] arrTempParameter = tempParameterString.split("=");
        if (arrTempParameter.length >= 2)
        {
            final String parameterKey = arrTempParameter[0];
            final String parameterValue = arrTempParameter[1];
            //do something with the parameters
        }
    }
}
user_2684790

Answering here because this is a popular thread. This is a clean solution in Kotlin that uses the recommended UrlQuerySanitizer api. See the official documentation. I have added a string builder to concatenate and display the params. 

    var myURL: String? = null
    // if the url is sent from a different activity where you set it to a value
    if (intent.hasExtra("my_value")) {
        myURL = intent.extras.getString("my_value")
    } else {
        myURL = intent.dataString
    }

    val sanitizer = UrlQuerySanitizer(myURL)
    // We don't want to manually define every expected query *key*, so we set this to true
    sanitizer.allowUnregisteredParamaters = true
    val parameterNamesToValues: List<UrlQuerySanitizer.ParameterValuePair> = sanitizer.parameterList
    val parameterIterator: Iterator<UrlQuerySanitizer.ParameterValuePair> = parameterNamesToValues.iterator()

    // Helper simply so we can display all values on screen
    val stringBuilder = StringBuilder()

    while (parameterIterator.hasNext()) {
        val parameterValuePair: UrlQuerySanitizer.ParameterValuePair = parameterIterator.next()
        val parameterName: String = parameterValuePair.mParameter
        val parameterValue: String = parameterValuePair.mValue

        // Append string to display all key value pairs
        stringBuilder.append("Key: $parameterName\nValue: $parameterValue\n\n")
    }

    // Set a textView's text to display the string
    val paramListString = stringBuilder.toString()
    val textView: TextView = findViewById(R.id.activity_title) as TextView
    textView.text = "Paramlist is \n\n$paramListString"

    // to check if the url has specific keys
    if (sanitizer.hasParameter("type")) {
        val type = sanitizer.getValue("type")
        println("sanitizer has type param $type")
    }
user_36349900
Related