android - HTTP 在 Android 模拟器中不起作用

Question

我尝试了多个 HTTP 类(HttpURLConnection、HTTPClient 等)，但它们在模拟器中不起作用。然后我决定在我的手机上测试它，它运行良好!

那么我该如何解决 Android 模拟器这种 HTTP 类不工作(而浏览器可以工作)的奇怪行为呢？他们让应用程序崩溃。

这是我的代码:

public static SimpleXML getResponse(String action, Map<String, String> params) {
     // Create a new HttpClient and Post Header
    HttpClient httpclient = new DefaultHttpClient();
    HttpPost httppost = new HttpPost(action);

    try {
        // Add your data
        List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(params.size());
        for(Map.Entry<String, String> heh : params.entrySet())
            nameValuePairs.add(new BasicNameValuePair(heh.getKey(), heh.getValue()));
        httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

        // Execute HTTP Post Request
        HttpResponse response = httpclient.execute(httppost);
        return SimpleXML.loadXml(response.getEntity().getContent());       

    } catch (ClientProtocolException e) {
        return null;
    } catch (IOException e) {
        return null;
    }   
}

LogCat 日志:

06-30 22:07:28.972: E/AndroidRuntime(682): FATAL EXCEPTION: main
06-30 22:07:28.972: E/AndroidRuntime(682): android.os.NetworkOnMainThreadException
06-30 22:07:28.972: E/AndroidRuntime(682):  at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117)
06-30 22:07:28.972: E/AndroidRuntime(682):  at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
06-30 22:07:28.972: E/AndroidRuntime(682):  at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
06-30 22:07:28.972: E/AndroidRuntime(682):  at java.net.InetAddress.getAllByName(InetAddress.java:214)
06-30 22:07:28.972: E/AndroidRuntime(682):  at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
06-30 22:07:28.972: E/AndroidRuntime(682):  at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
06-30 22:07:28.972: E/AndroidRuntime(682):  at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
06-30 22:07:28.972: E/AndroidRuntime(682):  at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
06-30 22:07:28.972: E/AndroidRuntime(682):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
06-30 22:07:28.972: E/AndroidRuntime(682):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
06-30 22:07:28.972: E/AndroidRuntime(682):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
06-30 22:07:28.972: E/AndroidRuntime(682):  at net.ekvium.air.API.getResponse(API.java:98)
06-30 22:07:28.972: E/AndroidRuntime(682):  at net.ekvium.air.MainActivity$1.onClick(MainActivity.java:62)
06-30 22:07:28.972: E/AndroidRuntime(682):  at android.view.View.performClick(View.java:4084)
06-30 22:07:28.972: E/AndroidRuntime(682):  at android.view.View$PerformClick.run(View.java:16966)
06-30 22:07:28.972: E/AndroidRuntime(682):  at android.os.Handler.handleCallback(Handler.java:615)
06-30 22:07:28.972: E/AndroidRuntime(682):  at android.os.Handler.dispatchMessage(Handler.java:92)
06-30 22:07:28.972: E/AndroidRuntime(682):  at android.os.Looper.loop(Looper.java:137)
06-30 22:07:28.972: E/AndroidRuntime(682):  at android.app.ActivityThread.main(ActivityThread.java:4745)
06-30 22:07:28.972: E/AndroidRuntime(682):  at java.lang.reflect.Method.invokeNative(Native Method)
06-30 22:07:28.972: E/AndroidRuntime(682):  at java.lang.reflect.Method.invoke(Method.java:511)
06-30 22:07:28.972: E/AndroidRuntime(682):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
06-30 22:07:28.972: E/AndroidRuntime(682):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
06-30 22:07:28.972: E/AndroidRuntime(682):  at dalvik.system.NativeStart.main(Native Method)

Answer 1

如果你看this Android documentation , 它解释了

NetworkOnMainThreadException:

The exception that is thrown when an application attempts to perform a networking operation on its main thread.

This is only thrown for applications targeting the Honeycomb SDK or higher. Applications targeting earlier SDK versions are allowed to do networking on their main event loop threads, but it's heavily discouraged.

因此，根据操作系统版本的不同，可能会强制执行(抛出异常)政策，禁止您在 UI 线程上发出网络请求。这可以解释为什么您的代码可以在设备上运行，而不是在模拟器上运行(如果它们具有不同的 Android 版本)。

您可以更改ThreadPolicy。但作为替代方案，我建议您再次查看 Android 文档中的声明。他们强烈不鼓励在主线程上执行网络操作，我当然同意他们的看法。

因此，与其将策略更改为使其合法，不如考虑更改代码，这样就不会在 UI 线程上调用您的 getResponse() 方法.

通常，您会使用 AsyncTask to do the work in the background .