Parse a URI String into Name-Value Collection

Question

I\'ve got the URI like this:

https://google.com.ua/oauth/authorize?client_id=SS&response_type=code&scope=N_FULL&access_type=offline&redirect_         


        

Answer 1

Kotlin's Answer with initial reference from https://stackoverflow.com/a/51024552/3286489, but with improved version by tidying up codes and provides 2 versions of it, and use immutable collection operations

Use java.net.URI to extract the Query. Then use the below provided extension functions

1. Assuming you only want the last value of query i.e. page2&page3 will get {page=3}, use the below extension function

    fun URI.getQueryMap(): Map {
        if (query == null) return emptyMap()

        return query.split("&")
                .mapNotNull { element -> element.split("=")
                        .takeIf { it.size == 2 && it.none { it.isBlank() } } }
                .associateBy({ it[0].decodeUTF8() }, { it[1].decodeUTF8() })
    }

    private fun String.decodeUTF8() = URLDecoder.decode(this, "UTF-8") // decode page=%22ABC%22 to page="ABC"

2. Assuming you want a list of all value for the query i.e. page2&page3 will get {page=[2, 3]}

    fun URI.getQueryMapList(): Map> {
        if (query == null) return emptyMap()

        return query.split("&")
                .distinct()
                .mapNotNull { element -> element.split("=")
                        .takeIf { it.size == 2 && it.none { it.isBlank() } } }
                .groupBy({ it[0].decodeUTF8() }, { it[1].decodeUTF8() })
    }

    private fun String.decodeUTF8() = URLDecoder.decode(this, "UTF-8") // decode page=%22ABC%22 to page="ABC"

The way to use it as below

    val uri = URI("schema://host/path/?page=&page=2&page=2&page=3")
    println(uri.getQueryMapList()) // Result is {page=[2, 3]}
    println(uri.getQueryMap()) // Result is {page=3}