Question

我知道这个主题已经在这里被问过，但我不明白为什么我的代码没有按预期工作。我需要在启动我的应用时检查数据连接，但它在某些平板电脑上崩溃（如Nexus 7），但不是全部崩溃。

我的代码：

public static boolean getNetworkState(Context pContext)
{
    ConnectivityManager connect =  (ConnectivityManager)pContext.getSystemService(Context.CONNECTIVITY_SERVICE);

    if(connect != null)
    {
        if (connect.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).isConnectedOrConnecting())
        {
            return true;
        }
        else 
        {
            return false;
        }
    }
    else
        return false;
}

public static boolean getWifiState(Context context)
{
    ConnectivityManager connect =  (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
    if ( connect.getNetworkInfo(ConnectivityManager.TYPE_WIFI).isConnectedOrConnecting())
    {
        return true;
    }
    else 
    {
        return false;
    }
}

连接检查：

if(Commons.getNetworkState(this) || Commons.getWifiState(this))
        {
            loadData();
        }
        else
        {
            Commons.getConnectivityErrorMessage(this);
        }

通常情况下，如果平板电脑不支持网络连接，“getNetworkState”中的“连接”对象应为空，但似乎并非如此，因为它在线崩溃

 if (connect.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).isConnectedOrConnecting())

这里有什么问题？权限已经写好

编辑：不幸的是，我没有平板电脑来测试这个问题。我只是在开发者控制台上有用户报告。用户使用Nexus 7报告了以下报告：

java.lang.RuntimeException: Unable to resume activity {com.meteociel.fr/com.meteociel.fr.activities.MeteocielActivity}: java.lang.RuntimeException: Unable to resume activity {com.meteociel.fr/com.meteociel.fr.activities.HomeActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2575)
at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2603)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2089)
at android.app.ActivityThread.access$600(ActivityThread.java:130)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.RuntimeException: Unable to resume activity {com.meteociel.fr/com.meteociel.fr.activities.HomeActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2575)
at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:178)
at android.app.LocalActivityManager.dispatchResume(LocalActivityManager.java:523)
at android.app.ActivityGroup.onResume(ActivityGroup.java:61)
at com.meteociel.fr.activities.MeteocielActivity.onResume(MeteocielActivity.java:69)
at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1184)
at android.app.Activity.performResume(Activity.java:5082)
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2565)
... 12 more
Caused by: java.lang.NullPointerException
at com.meteociel.fr.classes.Commons.getNetworkState(Commons.java:36)
at com.meteociel.fr.activities.HomeActivity.onResume(HomeActivity.java:98)
at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1184)
at android.app.Activity.performResume(Activity.java:5082)
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2565)
... 19 more

编辑2：我使用的所有权限：

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

Answer 1

此代码现在可以使用：

public static boolean getNetworkState(Context pContext)
    {
        ConnectivityManager connect = null;
        connect =  (ConnectivityManager)pContext.getSystemService(pContext.CONNECTIVITY_SERVICE);

        if(connect != null)
        {
            NetworkInfo result = connect.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
            if (result != null && result.isConnectedOrConnecting())
            {
                return true;
            }
            else 
            {
                return false;
            }
        }
        else
            return false;
    }

Answer 2

如果wifi或移动数据连接关闭，此函数将返回false。如果开启，它将返回true。

boolean IsThereNetkork(){
    boolean flag = false,mobile=false,wifi=false;

    ConnectivityManager manager=(ConnectivityManager) this.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activenetwork=manager.getActiveNetworkInfo();   
    if(activenetwork!=null){
        mobile=activenetwork.getType()==ConnectivityManager.TYPE_MOBILE;
        wifi=activenetwork.getType()==ConnectivityManager.TYPE_WIFI;
    if(activenetwork.isConnected()||activenetwork.isConnectedOrConnecting()){
        if(wifi==true||mobile==true){
            flag=true;
        }
        else if(wifi==false||mobile==false){
            flag=false;
        }
    }
    }
    else {
        flag=false;
    }
    return flag;
}

Android检查某些平板电脑崩溃时的网络连接

2 个答案: