blocks|key|2144758|text|找到了一个图书馆。看看这个库的功能会很有趣，我不认为它需要实现一个库。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2144759|代理|offset|length|2144760|关于如何使用它的一个示例：|2144761|main()+async+{
++++app.get('/',+(req,+res)+async+{
++++++++var+ua+=+new+UserAgent(req.headers.value('user-agent'));

++++++++if+(ua.isChrome)+{
++++++++++++res.redirect('/upgrade-your-browser');
++++++++++++return;
++++++++}+else+{
++++++++++++//+...
++++++++}
++++});
}|code-block|syntax|javascript|2144762|或者，如果要向http客户端添加用户代理，可以这样做：|2144763|Future<http.Response>+fetchPost()+{
++return+http.get(your_url,
++++//+Send+user-agent+header+to+your+backend
++++headers:+{HttpHeaders.userAgentHeader:+"your_user_agent"},
++);
}|2144764|您可以查看HttpHeaders来查看预定义标题的完整列表，尽管headers接受了一个映射，但如果需要，您可以创建自己的标头。|style|CODE|2144765|entityMap|0|LINK|mutability|MUTABLE|url|https://pub.dartlang.org/packages/user_agent^0|0|0|2|0|0|0|0|0|0|5|B|W|7|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|13|8|@]|9|@$D|14|E|15|1|16]]|A|$]]|$1|F|3|G|5|6|7|17|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|18|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|19|8|@]|9|@]|A|$]]|$1|O|3|P|5|J|7|1A|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|1B|8|@$D|1C|E|1D|S|T]|$D|1E|E|1F|S|T]]|9|@]|A|$]]|$1|U|3|-4|5|6|7|1G|8|@]|9|@]|A|$]]]|V|$W|$5|X|Y|Z|A|$10|11]]]]

Found a library that does it. It would be interesting to look at what the library does, i don't think it's needed to implement a library for that.

<a href="https://pub.dartlang.org/packages/user_agent" rel="nofollow noreferrer">https://pub.dartlang.org/packages/user_agent</a>

An example on how you would use it:

<pre><code>main() async {
 app.get('/', (req, res) async {
 var ua = new UserAgent(req.headers.value('user-agent'));

 if (ua.isChrome) {
 res.redirect('/upgrade-your-browser');
 return;
 } else {
 // ...
 }
 });
}
</code></pre>

Alternatively, if you want to add a user-agent to the http client, you can do it this way:

<pre><code>Future&lt;http.Response&gt; fetchPost() {
 return http.get(your_url,
 // Send user-agent header to your backend
 headers: {HttpHeaders.userAgentHeader: "your_user_agent"},
 );
}
</code></pre>

You can look at <code>HttpHeaders</code>to see the full list of predefined headers, although <code>headers</code> take a map, you could create your own header if you want.

blocks|key|2144785|text|我是通过调用本地方法来做到这一点的。首先，您必须在android主活动中添加方法通道。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2144786|@Override
protected+void+onCreate(Bundle+savedInstanceState)+{
++++super.onCreate(savedInstanceState);
++++GeneratedPluginRegistrant.registerWith(this);

++++new+MethodChannel(getFlutterView(),+CHANNEL).setMethodCallHandler(
++++++++++++new+MethodChannel.MethodCallHandler()+{
++++++++++++++++@Override
++++++++++++++++public+void+onMethodCall(MethodCall+call,+MethodChannel.Result+result)+{
++++++++++++++++++++if+(call.method.equals("getUserAgent"))+{
++++++++++++++++++++++++result.success(System.getProperty("http.agent"));
++++++++++++++++++++}+else+{
++++++++++++++++++++++++result.notImplemented();
++++++++++++++++++++}
++++++++++++++++}
++++++++++++});
}|code-block|syntax|javascript|2144787|然后，可以调用getUserAgent()方法，如下所示|offset|length|style|CODE|2144788|Future<String>+_getUserAgent()+async+{
++try+{
++++return+await+platform.invokeMethod('getUserAgent');
++}+catch+(e)+{
++++return+'Unknown';
++}
}|2144789|entityMap^0|0|0|7|E|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

I done it by calling native methods in flutter. First you have to add method channel in android Main Activity

<pre><code>@Override
protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 GeneratedPluginRegistrant.registerWith(this);

 new MethodChannel(getFlutterView(), CHANNEL).setMethodCallHandler(
 new MethodChannel.MethodCallHandler() {
 @Override
 public void onMethodCall(MethodCall call, MethodChannel.Result result) {
 if (call.method.equals("getUserAgent")) {
 result.success(System.getProperty("http.agent"));
 } else {
 result.notImplemented();
 }
 }
 });
}
</code></pre>

Then <code>getUserAgent()</code> method can be called in flutter like below

<pre><code>Future&lt;String&gt; _getUserAgent() async {
 try {
 return await platform.invokeMethod('getUserAgent');
 } catch (e) {
 return 'Unknown';
 }
}
</code></pre>

blocks|key|464676|text|您可以使用flutter_user_agent库：代理，以跨平台的方式获得它。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|464677|import+'package:flutter_user_agent/flutter_user_agent.dart';

...

++++String+ua+=+await+FlutterUserAgent.getPropertyAsync('userAgent');|code-block|syntax|javascript|464678|entityMap|0|LINK|mutability|MUTABLE|url|https://pub.dev/packages/flutter_user_agent^0|5|I|P|2|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

You can get it in a cross-platform way by using the <code>flutter_user_agent</code> library: <a href="https://pub.dev/packages/flutter_user_agent" rel="nofollow noreferrer">https://pub.dev/packages/flutter_user_agent</a>. 

<pre class="lang-dart prettyprint-override"><code>import 'package:flutter_user_agent/flutter_user_agent.dart';

...

 String ua = await FlutterUserAgent.getPropertyAsync('userAgent');

</code></pre>

blocks|key|464680|text|这是通过使用flutter_user_agent库：代理来实现的，如前所述|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|464681|String+_userAgent+=+await+FlutterUserAgent.getPropertyAsync('userAgent');

++++final+_response+=+await+http.get(_url,+headers:+{
++++++'Content-Type':+'application/json',
++++++'Accept-Charset':+'utf-8',
++++++'User-Agent':+'${_userAgent.toLowerCase()}',
++++});|code-block|syntax|javascript|464682|entityMap|0|LINK|mutability|MUTABLE|url|https://pub.dev/packages/flutter_user_agent^0|6|I|Q|2|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

this worked for me by using <code>flutter_user_agent</code> library: <a href="https://pub.dev/packages/flutter_user_agent" rel="nofollow noreferrer">https://pub.dev/packages/flutter_user_agent</a>
as mentioned above
<pre><code>String _userAgent = await FlutterUserAgent.getPropertyAsync('userAgent');

 final _response = await http.get(_url, headers: {
 'Content-Type': 'application/json',
 'Accept-Charset': 'utf-8',
 'User-Agent': '${_userAgent.toLowerCase()}',
 });
</code></pre>

I'm building a flutter app which needs to send user agent information along with the http request. I'm using <a href="https://pub.dartlang.org/packages/http" rel="nofollow noreferrer">http dart package</a> to send requests. How to get user agent string in flutter and use it with http package?

How to get device user agent information in Flutter

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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