HttpClientHandler in C# - Easy Guide
Tags: csharp, dotnet, programming, tutorial
Published: 2023-12-29 09:30:00

We’ll dive deep into understanding HttpClientHandler, see how it beautifully sits within the .NET ecosystem, and learn how it becomes our superhero when dealing with HTTP requests and responses.

## Understanding HttpClientHandler and its Importance in C# #

Before we delve deeper into HttpClientHandler, let’s give a warm welcome to our friend, HttpClient. Why? Because HttpClientHandler is the sidekick we need for our superhero HttpClient! That’s right; they’re the dynamic duo of network programming in C#. Let’s find out why!

### What is HttpClientHandler in C# #

HttpClientHandler is a class in .NET that provides a base class with properties and methods used by HttpClient for sending HTTP requests and receiving HTTP responses. So, it’s essentially the engine under the hood of HttpClient. Cool, huh?

Here is a fun fact – who knew that when we use an instance of HttpClient, we’re also making use of HttpClientHandler, even if we can’t see it? It’s true! HttpClientHandler is implicitly instantiated whenever we create an HttpClient. It’s like an invisible friend, always there for HttpClient.

### Significance of HttpClientHandler in .NET Applications

Now we know what HttpClientHandler is, but is it really that important? Oh, yes! HttpClientHandler is a master manipulator of HttpClient’s behavior and its HTTP requests and responses. Whether you’re adding headers, handling cookies, setting up request timeouts, or dealing with proxies, HttpClientHandler has got you covered.

## Delve Deeper into HttpClient C# #

Now that we’ve appreciated the role of HttpClientHandler let’s shift our spotlight onto HttpClient. What can it do? How can we use it effectively? Let’s dive in and understand its charm!

### How to Use HttpClient C# #

HttpClient is a class in C# designed to send HTTP requests and receive HTTP responses from a resource identified by a URI. Beckon your inner coder and check out this simple example:

```csharp
HttpClient client = new HttpClient();
 HttpResponseMessage response = await client.GetAsync("http://example.com/");
 if (response.IsSuccessStatusCode)
 {
     string responseBody = await response.Content.ReadAsStringAsync();
     Console.WriteLine(responseBody);
 }
```

In this short snippet, we’re performing a GET request to “http://example.com/” and then displaying the response if the Status Code is successful. Neat!

### C# HttpClient Example for Beginners

Let’s look at our beloved HttpClient in action! Run the following C# code in your favorite IDE (Visual Studio, JetBrains, or hey, even good ol’ Notepad):

```csharp
HttpClient client = new HttpClient();
client.BaseAddress = new Uri("http://example.com/");
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
```

This example shows setting up an HttpClient instance, and defining the base address for all subsequent requests and the acceptable media type.

### Role of System.Net.Http.HttpClient in Network Programming

In network programming, HttpClient is like your trusty steed, ready to perform HTTP operations like a boss. It’s powerful yet flexible, serving us asynchronous methods for all HTTP methods. Need to coordinate multiple HTTP requests? HttpClient can handle that like a champ. Oh, and did you hear it can be used for both mobile and desktop applications? Now that’s versatility!

## Practical Examples using HttpClientHandler and HttpClient in .NET Core

Now that we’ve gotten comfy with HttpClient and HttpClientHandler, let’s put our newfound knowledge to the test with a practical .NET Core example.

### .Net Core HttpClient Get Example and Explanation

```csharp
HttpClientHandler handler = new HttpClientHandler();
handler.AllowAutoRedirect = false; 

HttpClient client = new HttpClient(handler);
HttpResponseMessage response = await client.GetAsync("http://example.com");
```

In this code snippet, we instantiate an HttpClientHandler, disable automatic redirection, and use it to create an HttpClient. Then we perform a GET request; however, the HttpClient won’t follow redirect responses thanks to our handler. Neat, huh?

## HttpClientHandler and Security: Adding Authorization Headers

By now, you must be wondering, “Can HttpClientHandler help me with secured requests too?” The answer is a big “Yes!”. It can handle different kinds of authentication and headers.

### How to Add Basic Authentication in HttpClient C# #

Let’s illustrate this with an example.

```csharp
HttpClientHandler handler = new HttpClientHandler();
handler.Credentials = new NetworkCredential("username", "password");

HttpClient client = new HttpClient(handler);
```

This little piece of code shows how effortlessly you can use HttpClientHandler for Basic Authentication. It’s as easy as creating an HttpClientHandler, setting its Credentials property with username and password, and voila! Secured connection established!

### How to Add Bearer Token in HttpClient C# #

If you’re dealing with OAuth 2.0 authorization, there’s a good chance you’ll need to set a bearer token in the Authorization header. No problem! HttpClientHandler has got your back.

Check out this cool example.

```csharp
HttpClient client = new HttpClient();
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", "Your_Token");
```

In this example, we’re setting a bearer token in the Authorization header of HttpClient. And guess what? HttpClientHandler will implicitly take care of the rest. Amazing!

### How to Add Header in HttpClient C# #

Adding headers in HttpClient is a child’s game with HttpClientHandler. See for yourself!

```csharp
HttpClient client = new HttpClient();
client.DefaultRequestHeaders.Add("X-Custom-Header", "This is my value");
```

This code snippet adds a custom header to all requests made by the HttpClient. HttpClientHandler ensures the headers are included each time HttpClient makes a request. Easy peasy!

## Making API Calls using HttpClient

Apps these days are all about communication. HttpClient is like the backstage operator that subtly liaises between your app and the entire world outside.

### How to Call Get API in C# using HttpClient

Here is a basic example of how to make a GET API call using our superhero, HttpClient.

```csharp
HttpClient client = new HttpClient();
var response = await client.GetAsync("https://api.github.com/zen");
var result = await response.Content.ReadAsStringAsync();

Console.WriteLine(result);
```

In this example, we’re calling the GitHub Zen API, which provides inspirational quotes.

All hail HttpClient, the unsung hero of network programming in C#!

## HttpClientHandler in C#: A Recap

Well done, Codin’ Crusader! We’ve journeyed through the diverse landscape of HttpClient and HttpClientHandler, explored their powers, and unlocked the mysteries of network programming in .NET world.

Cheers to you and your newly acquired HttpClient skills! Remember, with great power(in C#) comes great responsibility! Do you think you’re ready to implement the lustrous HttpClient and HttpClientHandler in your next amazing C# project? Go for it, and let the coding gods always be in your favor!