在我开始下载一些文件之前，我有这段代码用来测试是否有网络连接。我遇到的问题是，我还在需要基于 Web 的登录表单的网络上进行测试(类似于酒店、机场，甚至飞机)。我正在使用的这段代码对于这种情况完全没用。在这些情况下，网络报告它 isAvailable 和 isConnected。这当然是个问题，因为我启动了一个失败的异步网络连接。我想知道是否有人知道我可以做些什么来确保我“真正”连接，或者是否有人对这个问题有任何建议。

这是我的代码块:

ConnectivityManager manager = (ConnectivityManager) context
        .getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = manager.getActiveNetworkInfo();

Log.e("", "Network info: "+networkInfo+" toString?: "+networkInfo.toString());
Log.e("", "getTypeName: "+networkInfo.getTypeName());
Log.e("", "isAvailable: "+networkInfo.isAvailable());
Log.e("", "isConnected: "+networkInfo.isConnected());

以下是我尝试代码块和结果的用例。

1x Verizon 信号

Network info: NetworkInfo: type: mobile[CDMA - 1xRTT], state: CONNECTED/CONNECTED, reason: connected, extra: , roaming: false, failover: true, isAvailable: true, isConnectedToProvisioningNetwork: false 

toString?: NetworkInfo: type: mobile[CDMA - 1xRTT], state: CONNECTED/CONNECTED, reason: connected, extra: , roaming: false, failover: true, isAvailable: true, isConnectedToProvisioningNetwork: false

getTypeName: mobile
isAvailable: true
isConnected: true

Verizon 上的 3G 信号

 Network info: NetworkInfo: type: mobile[CDMA - eHRPD], state: CONNECTED/CONNECTED, reason: linkPropertiesChanged, extra: VZWINTERNET, roaming: false, failover: false, isAvailable: true, isConnectedToProvisioningNetwork: false

 toString?: NetworkInfo: type: mobile[CDMA - eHRPD], state: CONNECTED/CONNECTED, reason: linkPropertiesChanged, extra: VZWINTERNET, roaming: false, failover: false, isAvailable: true, isConnectedToProvisioningNetwork: false

 getTypeName: mobile
 isAvailable: true
 isConnected: true

我设备上的飞行模式

Crash: networkInfo NullPointerException

没有 wifi - 没有移动数据(有效的飞行模式)

Crash: networkInfo NullPointerException

WiFi(未验证):

Network info: NetworkInfo: type: WIFI[], state: CONNECTED/CONNECTED, reason: (unspecified), extra: (none), roaming: false, failover: false, isAvailable: true 

toString: NetworkInfo: type: WIFI[], state: CONNECTED/CONNECTED, reason: (unspecified), extra: (none), roaming: false, failover: false, isAvailable: true

getTypeName: WIFI
isAvailable: true
isConnected: true

WiFi(未验证)第二台设备:

Network info: NetworkInfo: type: WIFI[], state: CONNECTED/CONNECTED, reason: (unspecified), extra: "myWifi", roaming: false, failover: false, isAvailable: true, isConnectedToProvisioningNetwork: false 

toString?: NetworkInfo: type: WIFI[], state: CONNECTED/CONNECTED, reason: (unspecified), extra: "myWifi", roaming: false, failover: false, isAvailable: true, isConnectedToProvisioningNetwork: false

getTypeName: WIFI
isAvailable: true
isConnected: true

WiFi(已验证)

Network info: NetworkInfo: type: WIFI[], state: CONNECTED/CONNECTED, reason: (unspecified), extra: (none), roaming: false, failover: false, isAvailable: true 

toString?: NetworkInfo: type: WIFI[], state: CONNECTED/CONNECTED, reason: (unspecified), extra: (none), roaming: false, failover: false, isAvailable: true

getTypeName: WIFI
isAvailable: true
isConnected: true

WiFi(已验证)第二台设备:

Network info: NetworkInfo: type: WIFI[], state: CONNECTED/CONNECTED, reason: (unspecified), extra: "myWifi", roaming: false, failover: false, isAvailable: true, isConnectedToProvisioningNetwork: false 

toString?: NetworkInfo: type: WIFI[], state: CONNECTED/CONNECTED, reason: (unspecified), extra: "myWifi", roaming: false, failover: false, isAvailable: true, isConnectedToProvisioningNetwork: false

getTypeName: WIFI
isAvailable: true
isConnected: true

如您所见，在我有未验证的 Wifi 和已验证的 Wifi 的情况下，我对 isAvailable 和 isConnected 为真。

最佳答案

检查这是否适合您。我是这样做的:

如下创建两个java文件:

NetworkConnectivity.java

package com.connectivity;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Handler;

public class NetworkConnectivity {

    private static NetworkConnectivity sharedNetworkConnectivity = null;

    private Activity activity = null;

    private final Handler handler = new Handler();
    private Runnable runnable = null;

    private boolean stopRequested = false;
    private boolean monitorStarted = false;

    private static final int NETWORK_CONNECTION_YES = 1;
    private static final int NETWORK_CONNECTION_NO = -1;
    private static final int NETWORK_CONNECTION_UKNOWN = 0;

    private int connected = NETWORK_CONNECTION_UKNOWN;

    public static final int MONITOR_RATE_WHEN_CONNECTED_MS = 5000;
    public static final int MONITOR_RATE_WHEN_DISCONNECTED_MS = 1000;

    private final List<NetworkMonitorListener> networkMonitorListeners = new ArrayList<NetworkMonitorListener>();

    private NetworkConnectivity() {
    }

    public synchronized static NetworkConnectivity sharedNetworkConnectivity() {
        if (sharedNetworkConnectivity == null) {
            sharedNetworkConnectivity = new NetworkConnectivity();
        }

        return sharedNetworkConnectivity;
    }

    public void configure(Activity activity) {
        this.activity = activity;
    }

    public synchronized boolean startNetworkMonitor() {
        if (this.activity == null) {
            return false;
        }

        if (monitorStarted) {
            return true;
        }

        stopRequested = false;
        monitorStarted = true;

        (new Thread(new Runnable() {
            @Override
            public void run() {
                doCheckConnection();
            }
        })).start();

        return true;
    }

    public synchronized void stopNetworkMonitor() {
        stopRequested = true;
        monitorStarted = false;
    }

    public void addNetworkMonitorListener(NetworkMonitorListener l) {
        this.networkMonitorListeners.add(l);
        this.notifyNetworkMonitorListener(l);
    }

    public boolean removeNetworkMonitorListener(NetworkMonitorListener l) {
        return this.networkMonitorListeners.remove(l);
    }

    private void doCheckConnection() {

        if (stopRequested) {
            runnable = null;
            return;
        }

        final boolean connectedBool = this.isConnected();
        final int _connected = (connectedBool ? NETWORK_CONNECTION_YES
                : NETWORK_CONNECTION_NO);

        if (this.connected != _connected) {

            this.connected = _connected;

            activity.runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    notifyNetworkMonitorListeners();
                }
            });
        }

        runnable = new Runnable() {
            @Override
            public void run() {
                doCheckConnection();
            }
        };

        handler.postDelayed(runnable,
                (connectedBool ? MONITOR_RATE_WHEN_CONNECTED_MS
                        : MONITOR_RATE_WHEN_DISCONNECTED_MS));
    }

    public boolean isConnected() {
        try {
            ConnectivityManager cm = (ConnectivityManager) activity
                    .getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo netInfo = cm.getActiveNetworkInfo();

            if (netInfo != null && netInfo.isConnected()) {
                return true;
            } else {
                return false;
            }
        } catch (Exception e) {
            return false;
        }
    }

    private void notifyNetworkMonitorListener(NetworkMonitorListener l) {
        try {
            if (this.connected == NETWORK_CONNECTION_YES) {
                l.connectionEstablished();
            } else if (this.connected == NETWORK_CONNECTION_NO) {
                l.connectionLost();
            } else {
                l.connectionCheckInProgress();
            }
        } catch (Exception e) {
        }
    }

    private void notifyNetworkMonitorListeners() {
        for (NetworkMonitorListener l : this.networkMonitorListeners) {
            this.notifyNetworkMonitorListener(l);
        }
    }

}

NetworkMonitorListener.java

package com.connectivity;

public interface NetworkMonitorListener {

    public void connectionEstablished();
    public void connectionLost();
    public void connectionCheckInProgress();
}

最后，用法:

NetworkConnectivity.sharedNetworkConnectivity().configure(this);
        NetworkConnectivity.sharedNetworkConnectivity().startNetworkMonitor();
        NetworkConnectivity.sharedNetworkConnectivity()
                .addNetworkMonitorListener(new NetworkMonitorListener() {
                    @Override
                    public void connectionCheckInProgress() {
                        // Okay to make UI updates (check-in-progress is rare)
                    }

                    @Override
                    public void connectionEstablished() {
                        // Okay to make UI updates -- do something now that
                        // connection is avaialble

                        Toast.makeText(getBaseContext(), "Connection established", Toast.LENGTH_SHORT).show();
                    }

                    @Override
                    public void connectionLost() {
                        // Okay to make UI updates -- bummer, no connection

                        Toast.makeText(getBaseContext(), "Connection lost.", Toast.LENGTH_LONG).show();
                    }
                });

通过上述用法，您将能够在运行时检查互联网连接。一旦失去互联网连接，Toast 就会出现(按照上面的代码)。

关于java - 安卓有网络吗？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/21058443/