通过HttpURLConnection函数连接到互联网时出现Android应用程序错误

Question

我有谁的功能是检测手机的互联网连接是否可用，是否可以，是否可以实际连接到互联网。

代码的第一部分运行良好，即检测手机的移动数据或Wi-Fi是否已打开。如果启用了互联网，则该功能会尝试使用HttpURLConnection连接到网页，以检测互联网连接是否可以实际访问互联网。

不幸的是，应用程序继续崩溃，并根据logcat错误错误是在这个代码urlc.connect()的行。

根据logcat，MainActivity.java上的第21行包含这段代码：utils.network()。 Utils.java上的第93行包含这段代码：urlc.connect()

public void network() {
    ConnectivityManager cm = (ConnectivityManager)_con.getSystemService(Context.CONNECTIVITY_SERVICE);

    NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
    boolean isConnected = activeNetwork != null && activeNetwork.isConnectedOrConnecting();
    if (isConnected) {
        msg = "Internet Available";
        try {
            HttpURLConnection urlc = (HttpURLConnection)
                    (new URL("http://clients3.google.com/generate_204")
                            .openConnection());
            urlc.setRequestProperty("User-Agent", "Android");
            urlc.setRequestProperty("Connection", "close");
            urlc.setConnectTimeout(1500);
            urlc.connect();
            if (urlc.getResponseCode() == HttpURLConnection.HTTP_OK) {
                msg += " and is connecting.";
            } else {
                msg += " but not connecting";
            }
            Log.e(TAG, "NO Error checking internet connection");
        } catch (IOException e) {
            Log.e(TAG, "Error checking internet connection", e);
        }
    } else {
        msg = "Internet Unavailable";
    }
    Toast toast = Toast.makeText(_con, msg, Toast.LENGTH_LONG);
    toast.show();
}

logcat的

09-08 06:02:00.534 4476-4476/com.appsite.appname E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.appsite.appname, PID: 4476
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.appsite.appname/com.appsite.appname.MainActivity}: android.os.NetworkOnMainThreadException
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2572)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2654)
    at android.app.ActivityThread.-wrap11(ActivityThread.java)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1488)
    at android.os.Handler.dispatchMessage(Handler.java:111)
    at android.os.Looper.loop(Looper.java:207)
    at android.app.ActivityThread.main(ActivityThread.java:5728)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:679)
 Caused by: android.os.NetworkOnMainThreadException
    at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1288)
    at java.net.InetAddress.lookupHostByName(InetAddress.java:432)
    at java.net.InetAddress.getAllByNameImpl(InetAddress.java:253)
    at java.net.InetAddress.getAllByName(InetAddress.java:215)
    at com.android.okhttp.internal.Network$1.resolveInetAddresses(Network.java:29)
    at com.android.okhttp.internal.http.RouteSelector.resetNextInetSocketAddress(RouteSelector.java:188)
    at com.android.okhttp.internal.http.RouteSelector.nextProxy(RouteSelector.java:157)
    at com.android.okhttp.internal.http.RouteSelector.next(RouteSelector.java:100)
    at com.android.okhttp.internal.http.HttpEngine.createNextConnection(HttpEngine.java:368)
    at com.android.okhttp.internal.http.HttpEngine.nextConnection(HttpEngine.java:351)
    at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:341)
    at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:259)
    at com.android.okhttp.internal.huc.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:454)
    at com.android.okhttp.internal.huc.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:114)
    at com.appsite.appname.utils.Utils.network(Utils.java:93)
    at com.appsite.appname.MainActivity.onCreate(MainActivity.java:21)
    at android.app.Activity.performCreate(Activity.java:6301)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1113)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2519)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2654) 
    at android.app.ActivityThread.-wrap11(ActivityThread.java) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1488) 
    at android.os.Handler.dispatchMessage(Handler.java:111) 
    at android.os.Looper.loop(Looper.java:207) 
    at android.app.ActivityThread.main(ActivityThread.java:5728) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:679) 

Answer 1

请尝试以下行创建

StrictMode.ThreadPolicy policy = new
StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);

Answer 2

你正在主线程上发出网络请求。使用后台线程发出网络请求。这是问题的根源。

Caused by: android.os.NetworkOnMainThreadException