HttpURLConnection.getResponse码错误

Question

在我的android应用程序中，我试图检查是否有互联网接入，以及是否需要下载一些数据。但是，当我运行下面的代码来验证连接时，它返回的是.getResponseCode()方法-1而不是200，即使有一个有效的连接。该设备通过4G或WIFI连接到互联网上，但不起作用。安装在设备上的其他应用程序可以访问互联网。

protected Boolean doInBackground(String... args) {
        ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo netInfo = cm.getActiveNetworkInfo();
        if (netInfo != null && netInfo.isConnected()) {
            try {
                URL url = new URL("http://www.google.com");
                HttpURLConnection urlc = (HttpURLConnection) url.openConnection();
                urlc.setConnectTimeout(3000);
                urlc.connect();
                if (urlc.getResponseCode() == 200) {
                    return true;
                }
            } catch (MalformedURLException e1) {
                e1.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return false;
    }

AndroidManifests.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.sg.help">

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

UPDATE添加了以下调试输出。如您所见，responseCode是-1。

urlc = {HttpURLConnectionImpl@19895} "com.android.okhttp.internal.http.HttpURLConnectionImpl:http://www.google.com"
 client = {OkHttpClient@19909} 
 handshake = null
 httpEngine = {HttpEngine@19910} 
 httpEngineFailure = null
 requestHeaders = {Headers$Builder@19911} 
 route = {Route@19912} 
 fixedContentLength = -1
 redirectionCount = 0
 method = {String@19913} "GET"
 responseMessage = null
 fixedContentLengthLong = -1
 chunkLength = -1
 fixedContentLength = -1
 instanceFollowRedirects = true
 responseCode = -1
 contentType = null
 defaultHandler = {URLConnection$DefaultContentHandler@19914} 
 url = {URL@19883} "http://www.google.com"
 allowUserInteraction = false
 ifModifiedSince = 0
 lastModified = -1
 connectTimeout = 0
 connected = true
 doInput = true
 doOutput = false
 readTimeout = 0
 useCaches = true
 shadow$_klass_ = {Class@17437} "class com.android.okhttp.internal.http.HttpURLConnectionImpl"
 shadow$_monitor_ = -1761921262

Answer 1

尝试更改您的URL，例如https://www.android.com/。此外，尝试断开您的httpconnection之后，看看它是否有帮助。

断开连接。一旦读取了响应体，就应该通过调用disconnect()来关闭HttpURLConnection。断开连接会释放连接所持有的资源，因此它们可能会被关闭或重用。

http://developer.android.com/reference/java/net/HttpURLConnection.html

试试看以下几点。

URL url = new URL("https://www.android.com");
                HttpURLConnection urlc = (HttpURLConnection) url.openConnection();
                urlc.setConnectTimeout(5000);
                urlc.connect();
                if (urlc.getResponseCode() == 200) {
                    urlc.disconnect();
                    return true;
                }