Introduction

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The easiest HTTP networking library for Kotlin/Android.

You are looking at the documentation for 2.x.y.. If you are looking for the documentation for 1.x.y, checkout the 1.16.0 README.md

Features

  • HTTP GET/POST/PUT/DELETE/HEAD/PATCH requests in a fluent style interface

  • Asynchronous and blocking requests

  • Download as a file

  • Upload files, Blobs, DataParts as multipart/form-data

  • Cancel asynchronous request

  • Debug logging / convert to cUrl call

  • Deserialization into POJO / POKO

  • Requests as coroutines

  • API Routing

Installation

We offer maven and jitpack installations. Maven via bintray only has stable releases but jitpack can be used to build any branch, commit and version.

Maven

You can download and install Fuel with Maven and Gradle. The core package has the following dependencies:

  • Kotlin - Kotlin

  • Result - 2.2.0

//core
implementation 'com.github.kittinunf.fuel:fuel:<latest-version>'
//packages
implementation 'com.github.kittinunf.fuel:<package>:<latest-version>'

Each of the extensions / integrations has to be installed separately.

Package

Description

fuel

Core package

fuel-android

Android: Automatically invoke handler on Main Thread when using Android Module

fuel-coroutines

KotlinX: Execution with coroutines

fuel-forge

Deserialization: Forge

fuel-gson

(De)serialization: Gson

fuel-jackson

Deserialization: Jackson

fuel-json

Deserialization: Json

fuel-kotlinx-serialization

(De)serialization: KotlinX Serialization

fuel-livedata

Android Architectures: Responses as LiveData

fuel-moshi

Deserialization: Moshi

fuel-reactor

Reactive Programming: Responses as Mono (Project Reactor 3.x)

fuel-rxjava

Reactive Programming: Responses as Single (RxJava 2.x)

fuel-stetho

Utility: Debug utility for Android on Chrome Developer Tools, Stetho

Jitpack

If you want a SNAPSHOT distribution, you can use Jitpack

repositories {
maven(url = "https://jitpack.io") {
name = "jitpack"
}
}
dependencies {
//core
implementation(group = "com.github.kittinunf.fuel", name = "fuel", version = "-SNAPSHOT")
//packages
// replace <package> with the package name e.g. fuel-coroutines
implementation(group = "com.github.kittinunf.fuel", name = "<package>", version = "-SNAPSHOT")
}

or

dependencies {
//core and/or packages
// replace <package> with the package name e.g. fuel-coroutines
listof("fuel", "<package>").forEach {
implementation(group = "com.github.kittinunf.fuel", name = it, version = "-SNAPSHOT")
}
}

Configuration

  • group is made up of com.github as well as username and project name

  • name is the subproject, this may be any of the packages listed in the installation instructions eg. fuel, fuel-coroutines, fuel-kotlinx-serialization, etc

  • version can be the latest master-SMAPSHOT or -SNAPSHOT which always points at the HEAD or any other branch, tag or commit hash, e.g. as listed on jitpack.io.

We recommend not using SNAPSHOT builds, but a specific commit in a specific branch (like a commit on master), because your build will then be stable.

Build time-out

Have patience when updating the version of fuel or building for the first time as jitpack will build it, and this may cause the request to jitpack to time out. Wait a few minutes and try again (or check the status on jitpack).

NOTE: do not forget to add the kotlinx repository when using coroutines or serialization

Forks

Jitpack.io also allows to build from fuel forks. If a fork's username is $yourname,

  • adjust group to com.github.$yourName.fuel

  • and look for version on https://jitpack.io/#$yourName/Fuel

Quick start

Fuel requests can be made on the Fuel namespace object, any FuelManager or using one of the String extension methods. If you specify a callback the call is async, if you don't it's blocking.

Async Usage Example

import com.github.kittinunf.fuel.httpGet
import com.github.kittinunf.result.Result;
fun main(args: Array<String>) {
val httpAsync = "https://httpbin.org/get"
.httpGet()
.responseString { request, response, result ->
when (result) {
is Result.Failure -> {
val ex = result.getException()
println(ex)
}
is Result.Success -> {
val data = result.get()
println(data)
}
}
}
httpAsync.join()
}

Blocking Usage Example

import com.github.kittinunf.fuel.httpGet
import com.github.kittinunf.result.Result;
fun main(args: Array<String>) {
val (request, response, result) = "https://httpbin.org/get"
.httpGet()
.responseString()
when (result) {
is Result.Failure -> {
val ex = result.getException()
println(ex)
}
is Result.Success -> {
val data = result.get()
println(data)
}
}
}

// You can also use Fuel.get("https://httpbin.org/get").responseString { ... } // You can also use FuelManager.instance.get("...").responseString { ... }

`Fuel` and the extension methods use the `FuelManager.instance` under the hood. You can use this FuelManager to change the default behaviour of all requests:
```kotlin
FuelManager.instance.basePath = "https://httpbin.org"
"/get"
.httpGet()
.responseString { request, response, result -> /*...*/ }
// This is a GET request to "https://httpbin.org/get"

Detailed usage

Check each of the packages documentations or the Wiki for more features, usages and examples. Are you looking for basic usage on how to set headers, authentication, request bodies and more? fuel: Basic usage is all you need.

Basic functionality

Responses

(De)serialization

Utility

Other libraries

If you like Fuel, you might also like other libraries of mine;

  • Result - The modelling for success/failure of operations in Kotlin

  • Fuse - A simple generic LRU memory/disk cache for Android written in Kotlin

  • Forge - Functional style JSON parsing written in Kotlin

  • ReactiveAndroid - Reactive events and properties with RxJava for Android SDK

Credits

Fuel is brought to you by contributors.

Licenses

Fuel is released under the MIT license.