Java 显示当前使用的公共IPv4地址的Android应用程序

我正在尝试构建一个简单的Android应用程序，它向ipv4.icanhazip.com发出请求，并将公共IP地址返回到屏幕上

下面的程序将在IntelliJ上运行，但在Android Studio上构建并在我的Android设备上执行时不会运行。当按下按钮时，应用程序崩溃。当它应该只在屏幕上显示当前使用的公共IP地址时。任何帮助都将不胜感激

下面是按下dumpWifi按钮时调用的方法

public void dumpWifi(View view) throws IOException {
    PrimeSinister ip = new PrimeSinister();
    ip.returnIp();
}

下面是发出请求并返回公共IP地址的类

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;

public class PrimeSinister {

    public String returnIp() throws IOException {
         URL publicIp = new URL("https://ipv4.icanhazip.com/");
         BufferedReader in = new BufferedReader(new InputStreamReader(publicIp.openStream()));

         String ip = in.readLine();

         return ip;
     }
}

以下是我在Android上运行应用程序后看到的例外情况。奇怪的是，我在IntelliJ上运行了相同的程序，并按预期成功地返回了IP地址

Process: com.example.wifidumper, PID: 20770
java.lang.IllegalStateException: Could not execute method for android:onClick
    at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:402)
    at android.view.View.performClick(View.java:7140)
    at android.view.View.performClickInternal(View.java:7117)
    at android.view.View.access$3500(View.java:801)
    at android.view.View$PerformClick.run(View.java:27351)
    at android.os.Handler.handleCallback(Handler.java:883)
    at android.os.Handler.dispatchMessage(Handler.java:100)
    at android.os.Looper.loop(Looper.java:214)
    at android.app.ActivityThread.main(ActivityThread.java:7356)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
 Caused by: java.lang.reflect.InvocationTargetException
    at java.lang.reflect.Method.invoke(Native Method)
    at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:397)
    at android.view.View.performClick(View.java:7140) 
    at android.view.View.performClickInternal(View.java:7117) 
    at android.view.View.access$3500(View.java:801) 
    at android.view.View$PerformClick.run(View.java:27351) 
    at android.os.Handler.handleCallback(Handler.java:883) 
    at android.os.Handler.dispatchMessage(Handler.java:100) 
    at android.os.Looper.loop(Looper.java:214) 
    at android.app.ActivityThread.main(ActivityThread.java:7356) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930) 
 Caused by: android.os.NetworkOnMainThreadException
    at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1565)
    at java.net.Inet6AddressImpl.lookupHostByName(Inet6AddressImpl.java:115)
    at java.net.Inet6AddressImpl.lookupAllHostAddr(Inet6AddressImpl.java:103)
    at java.net.InetAddress.getAllByName(InetAddress.java:1152)
    at com.android.okhttp.Dns$1.lookup(Dns.java:41)
    at com.android.okhttp.internal.http.RouteSelector.resetNextInetSocketAddress(RouteSelector.java:178)
    at com.android.okhttp.internal.http.RouteSelector.nextProxy(RouteSelector.java:144)
    at com.android.okhttp.internal.http.RouteSelector.next(RouteSelector.java:86)
    at com.android.okhttp.internal.http.StreamAllocation.findConnection(StreamAllocation.java:176)
    at com.android.okhttp.internal.http.StreamAllocation.findHealthyConnection(StreamAllocation.java:128)
    at com.android.okhttp.internal.http.StreamAllocation.newStream(StreamAllocation.java:97)
    at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:289)
    at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:232)
    at com.android.okhttp.internal.huc.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:465)
    at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:411)
    at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:248)
    at com.android.okhttp.internal.huc.DelegatingHttpsURLConnection.getInputStream(DelegatingHttpsURLConnection.java:211)
    at com.android.okhttp.internal.huc.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:30)
    at java.net.URL.openStream(URL.java:1072)
    at com.example.wifidumper.PrimeSinister.returnIp(PrimeSinister.java:12)
    at com.example.wifidumper.MainActivity.dumpWifi(MainActivity.java:38)
    at java.lang.reflect.Method.invoke(Native Method) 
    at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:397) 
    at android.view.View.performClick(View.java:7140) 
    at android.view.View.performClickInternal(View.java:7117) 
    at android.view.View.access$3500(View.java:801) 
    at android.view.View$PerformClick.run(View.java:27351) 
    at android.os.Handler.handleCallback(Handler.java:883) 
    at android.os.Handler.dispatchMessage(Handler.java:100) 
    at android.os.Looper.loop(Looper.java:214) 
    at android.app.ActivityThread.main(ActivityThread.java:7356) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930) 

---

2020-06-29 22:10:07.72320770-20770/？I/进程：发送信号。PID:20770 SIG:9

您不能在UI线程中发送网络请求，事实上，您不需要使用java本机网络库，这样更好