我得到了一个AsyncTask，应该检查对主机名的网络访问。但是doInBackground()永远不会超时。有人知道吗?
public class HostAvailabilityTask extends AsyncTask<String, Void, Boolean> {
private Main main;
public HostAvailabilityTask(Main main) {
this.main = main;
}
protected Boolean doInBackground(String... params) {
Main.Log("doInBackground() isHostAvailable():"+params[0]);
try {
return InetAddress.getByName(params[0]).isReachable(30);
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return false;
}
protected void onPostExecute(Boolean... result) {
Main.Log("onPostExecute()");
if(result[0] == false) {
main.setContentView(R.layout.splash);
return;
}
main.continueAfterHostCheck();
}
}
我已经经历了所有的答案，我想出了我自己的答案，首先检查互联网是否可用，如果互联网可用，然后检查它是否活跃。
我已经包括了所有必要的方法和类来检查活跃的Internet连接。
NetworkUtils.class
public class NetworkUtils {
public static final int STATUS_CONNECTED = 0 ;
public static boolean isInternetAvailable(Context ctx){
ConnectivityManager cm = (ConnectivityManager)ctx.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
return activeNetwork != null && activeNetwork.isConnectedOrConnecting();
}
public static int isInternetActiveWithPing() {
try {
Runtime runtime = Runtime.getRuntime();
Process process = runtime.exec("/system/bin/ping -c 1 8.8.8.8");
int exitValue = process.waitFor();
return exitValue;
} catch (Exception ex) {
return -1;
}
}
public static boolean isInternetActiveWithInetAddress() {
try {
InetAddress inetAddress = InetAddress.getByName("www.google.com");
return inetAddress != null && !inetAddress.toString().equals("");
} catch (Exception ex) {
return false;
}
}
public static void displayInternetConnectionMessage(Context ctx){
Toast.makeText(ctx, "Check Internet Connection", Toast.LENGTH_SHORT).show();
}
}
你可以使用下面的代码检查互联网是否活跃:
private void checkInternetConnection() {
if (NetworkUtils.isInternetAvailable(this)) {
new Thread(new Runnable() {
@Override
public void run() {
if (NetworkUtils.isInternetActiveWithPing() == NetworkUtils.STATUS_CONNECTED) {
performNetworkingOperations();
} else {
if (NetworkUtils.isInternetActiveWithInetAddress()) {
performNetworkingOperations();
} else {
displayConnectionMessage();
}
}
}
}).start();
} else {
displayConnectionMessage();
}
}
private void performNetworkingOperations() {
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(MainActivity.this, "Internet is Available", Toast.LENGTH_SHORT).show();
}
});
}
private void displayConnectionMessage() {
runOnUiThread(new Runnable() {
@Override
public void run() {
NetworkUtils.displayInternetConnectionMessage(MainActivity.this);
}
});
}
从以下链接找到并修改(!):
在你的manifest文件中至少添加:
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
如果您正在访问它，您可能已经拥有INTERNET权限。那么一个允许测试连通性的布尔函数是:
private boolean checkInternetConnection() {
ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
// test for connection
if (cm.getActiveNetworkInfo() != null
&& cm.getActiveNetworkInfo().isAvailable()
&& cm.getActiveNetworkInfo().isConnected()) {
return true;
} else {
Log.v(TAG, "Internet Connection Not Present");
return false;
}
}
检查这段代码…这对我很有用:)
public static void isNetworkAvailable(final Handler handler, final int timeout) {
// ask fo message '0' (not connected) or '1' (connected) on 'handler'
// the answer must be send before before within the 'timeout' (in milliseconds)
new Thread() {
private boolean responded = false;
@Override
public void run() {
// set 'responded' to TRUE if is able to connect with google mobile (responds fast)
new Thread() {
@Override
public void run() {
HttpGet requestForTest = new HttpGet("http://m.google.com");
try {
new DefaultHttpClient().execute(requestForTest); // can last...
responded = true;
}
catch (Exception e) {
}
}
}.start();
try {
int waited = 0;
while(!responded && (waited < timeout)) {
sleep(100);
if(!responded ) {
waited += 100;
}
}
}
catch(InterruptedException e) {} // do nothing
finally {
if (!responded) { handler.sendEmptyMessage(0); }
else { handler.sendEmptyMessage(1); }
}
}
}.start();
}
然后，我定义处理程序:
Handler h = new Handler() {
@Override
public void handleMessage(Message msg) {
if (msg.what != 1) { // code if not connected
} else { // code if connected
}
}
};
.．.并启动测试:
isNetworkAvailable(h,2000); // get the answser within 2000 ms
非常重要的是检查我们是否与isAvailable()有连接，以及是否可能与isConnected()建立连接
private static ConnectivityManager manager;
public static boolean isOnline(Context context) {
ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
return networkInfo != null && networkInfo.isAvailable() && networkInfo.isConnected();
}
你可以取消网络活动WiFi的类型:
public static boolean isConnectedWifi(Context context) {
ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
return networkInfo != null && networkInfo.getType() == ConnectivityManager.TYPE_WIFI;
}
或手机Móvil:
public static boolean isConnectedMobile(Context context) {
ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
return networkInfo != null && networkInfo.getType() == ConnectivityManager.TYPE_MOBILE;
}
不要忘记权限:
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
