网络连接/互联网接入
isConnectedOrConnecting()(在大多数回答中使用)检查任何网络连接
要了解这些网络是否有internet接入，请使用以下方法之一
A) Ping服务器(简单)
// ICMP
public boolean isOnline() {
Runtime runtime = Runtime.getRuntime();
try {
Process ipProcess = runtime.exec("/system/bin/ping -c 1 8.8.8.8");
int exitValue = ipProcess.waitFor();
return (exitValue == 0);
}
catch (IOException e) { e.printStackTrace(); }
catch (InterruptedException e) { e.printStackTrace(); }
return false;
}
+可以在主线程上运行
在一些旧设备上不能工作(Galays S3等)，如果没有网络，它会阻塞一段时间。
B)连接到Internet上的Socket(高级)
// TCP/HTTP/DNS (depending on the port, 53=DNS, 80=HTTP, etc.)
public boolean isOnline() {
try {
int timeoutMs = 1500;
Socket sock = new Socket();
SocketAddress sockaddr = new InetSocketAddress("8.8.8.8", 53);
sock.connect(sockaddr, timeoutMs);
sock.close();
return true;
} catch (IOException e) { return false; }
}
+非常快(任何一种方式)，适用于所有设备，非常可靠
-不能在UI线程上运行
这工作非常可靠，在每个设备上，非常快。它需要在一个单独的任务中运行(例如ScheduledExecutorService或AsyncTask)。
可能的问题
Is it really fast enough?
Yes, very fast ;-)
Is there no reliable way to check internet, other than testing something on the internet?
Not as far as I know, but let me know, and I will edit my answer.
What if the DNS is down?
Google DNS (e.g. 8.8.8.8) is the largest public DNS in the world. As of 2018 it handled over a trillion queries a day [1]. Let 's just say, your app would probably not be the talk of the day.
Which permissions are required?
<uses-permission android:name="android.permission.INTERNET" />
Just internet access - surprise ^^ (Btw have you ever thought about, how some of the methods suggested here could even have a remote glue about internet access, without this permission?)
额外:一次性RxJava/RxAndroid示例(Kotlin)
fun hasInternetConnection(): Single<Boolean> {
return Single.fromCallable {
try {
// Connect to Google DNS to check for connection
val timeoutMs = 1500
val socket = Socket()
val socketAddress = InetSocketAddress("8.8.8.8", 53)
socket.connect(socketAddress, timeoutMs)
socket.close()
true
} catch (e: IOException) {
false
}
}
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
}
///////////////////////////////////////////////////////////////////////////////////
// Usage
hasInternetConnection().subscribe { hasInternet -> /* do something */}
额外:一次性RxJava/RxAndroid示例(Java)
public static Single<Boolean> hasInternetConnection() {
return Single.fromCallable(() -> {
try {
// Connect to Google DNS to check for connection
int timeoutMs = 1500;
Socket socket = new Socket();
InetSocketAddress socketAddress = new InetSocketAddress("8.8.8.8", 53);
socket.connect(socketAddress, timeoutMs);
socket.close();
return true;
} catch (IOException e) {
return false;
}
}).subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread());
}
///////////////////////////////////////////////////////////////////////////////////
// Usage
hasInternetConnection().subscribe((hasInternet) -> {
if(hasInternet) {
}else {
}
});
额外:一次性AsyncTask示例
注意:这是如何执行请求的另一个示例。然而，由于AsyncTask已弃用，它应该被你的应用程序的线程调度，Kotlin协程，Rx，…
class InternetCheck extends AsyncTask<Void,Void,Boolean> {
private Consumer mConsumer;
public interface Consumer { void accept(Boolean internet); }
public InternetCheck(Consumer consumer) { mConsumer = consumer; execute(); }
@Override protected Boolean doInBackground(Void... voids) { try {
Socket sock = new Socket();
sock.connect(new InetSocketAddress("8.8.8.8", 53), 1500);
sock.close();
return true;
} catch (IOException e) { return false; } }
@Override protected void onPostExecute(Boolean internet) { mConsumer.accept(internet); }
}
///////////////////////////////////////////////////////////////////////////////////
// Usage
new InternetCheck(internet -> { /* do something with boolean response */ });
