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| </p></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="http-client"></a>Chapter 22. HTTP Client</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="section"><a href="http-client.html#http-client-intro">Introduction</a></span></dt><dt><span class="section"><a href="http-client-api.html">API Usage</a></span></dt><dt><span class="section"><a href="http-client-cookie.html">Cookies Support</a></span></dt><dt><span class="section"><a href="http-client-authentication.html">Authentication Support</a></span></dt><dt><span class="section"><a href="http-client-proxy.html">Proxy Support</a></span></dt><dt><span class="section"><a href="http-client-transport.html">Pluggable Transports</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="http-client-intro"></a>Introduction</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="http-client.html#http-client-init">Starting HttpClient</a></span></dt><dt><span class="section"><a href="http-client.html#_stopping_httpclient">Stopping HttpClient</a></span></dt></dl></div><p>The Jetty HTTP client module provides easy-to-use APIs and utility classes to perform HTTP (or HTTPS) requests.</p><p>Jetty’s HTTP client is non-blocking and asynchronous. |
| It offers an asynchronous API that never blocks for I/O, making it very efficient in thread utilization and well suited for high performance scenarios such as load testing or parallel computation.</p><p>However, when all you need to do is to perform a <code class="literal">GET</code> request to a resource, Jetty’s HTTP client offers also a synchronous API; a programming interface |
| where the thread that issued the request blocks until the request/response conversation is complete.</p><p>Jetty’s HTTP client supports different <a class="link" href="http-client-transport.html" title="Pluggable Transports">transports</a>: HTTP/1.1, FastCGI and HTTP/2. |
| This means that the semantic of a HTTP request (that is, " <code class="literal">GET</code> me the resource <code class="literal">/index.html</code> ") can be carried over the network in different formats. |
| The most common and default format is HTTP/1.1. |
| That said, Jetty’s HTTP client can carry the same request using the FastCGI format or the new HTTP/2 format.</p><p>The FastCGI transport is heavily used in Jetty’s <a class="link" href="fastcgi.html" title="Chapter 17. FastCGI Support">FastCGI support</a> that allows Jetty to work as a reverse proxy to PHP (exactly like Apache or Nginx do) and therefore be able to serve - for example - WordPress websites.</p><p>The HTTP/2 transport allows Jetty’s HTTP client to perform requests using HTTP/2 to HTTP/2 enabled web sites, see also Jetty’s <a class="link" href="http2.html" title="Chapter 16. HTTP/2">HTTP/2 support</a>.</p><p>Out of the box features that you get with the Jetty HTTP client include:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Redirect support - redirect codes such as 302 or 303 are automatically followed.</li><li class="listitem">Cookies support - cookies sent by servers are stored and sent back to servers in matching requests.</li><li class="listitem">Authentication support - HTTP "Basic" and "Digest" authentications are supported, others are pluggable.</li><li class="listitem">Forward proxy support - HTTP proxying and SOCKS4 proxying.</li></ul></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="http-client-init"></a>Starting HttpClient</h3></div></div></div><p>The main class is named <code class="literal">org.eclipse.jetty.client.HttpClient</code>.</p><p>You can think of a <code class="literal">HttpClient</code> instance as a browser instance. |
| Like a browser it can make requests to different domains, it manages redirects, cookies and authentication, you can configure it with a proxy, and |
| it provides you with the responses to the requests you make.</p><p>In order to use <code class="literal">HttpClient</code>, you must instantiate it, configure it, and then start it:</p><pre xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times"><code>// Instantiate HttpClient |
| HttpClient httpClient = new HttpClient(); |
| |
| // Configure HttpClient, for example: |
| httpClient.setFollowRedirects(false); |
| |
| // Start HttpClient |
| httpClient.start();</code></pre><p>You may create multiple instances of <code class="literal">HttpClient</code>, but typically one instance is enough for an application. |
| There are several reasons for having multiple <code class="literal">HttpClient</code> instances including, but not limited to:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">You want to specify different configuration parameters (for example, one instance is configured with a forward proxy while another is not)</li><li class="listitem">You want the two instances to behave like two different browsers and hence have different cookies, different authentication credentials…​etc.</li><li class="listitem">You want to use different transports</li></ul></div><p>When you create a <code class="literal">HttpClient</code> instance using the parameterless constructor, you will only be able to perform plain HTTP requests and you will not be able to perform HTTPS requests.</p><p>In order to perform HTTPS requests, you should create first a <a class="link" href="http://www.eclipse.org/jetty/javadoc/9.3.28.v20191105/org/eclipse/jetty/util/ssl/SslContextFactory.html" target="_top"><code class="literal">SslContextFactory</code></a>, configure it, and pass it to the <code class="literal">HttpClient</code> constructor. |
| When created with a <code class="literal">SslContextFactory</code>, the <code class="literal">HttpClient</code> will be able to perform both HTTP and HTTPS requests to any domain.</p><pre xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times"><code>// Instantiate and configure the SslContextFactory |
| SslContextFactory sslContextFactory = new SslContextFactory(); |
| |
| // Instantiate HttpClient with the SslContextFactory |
| HttpClient httpClient = new HttpClient(sslContextFactory); |
| |
| // Configure HttpClient, for example: |
| httpClient.setFollowRedirects(false); |
| |
| // Start HttpClient |
| httpClient.start();</code></pre></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_stopping_httpclient"></a>Stopping HttpClient</h3></div></div></div><p>It is recommended that when your application stops, you also stop the <code class="literal">HttpClient</code> instance (or instances) that you are using.</p><pre xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times"><code>httpClient.stop();</code></pre><p>Stopping <code class="literal">HttpClient</code> makes sure that the memory it holds (for example, authentication credentials, cookies, etc.) is released, and that the thread pool and scheduler are properly stopped allowing all threads used by <code class="literal">HttpClient</code> to exit.</p></div></div></div><script type="text/javascript"> |
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