java - NetworkInfo.isConnected() 和 NetworkInfo.getDetailedState() == NetworkInfo.DetailedState.CONNECTED 之间的区别。用什么？

Question

我想知道哪种方法可以准确地检查网络状态以成功连接。

Answer 1

所以如果我们看一下 source code在 NetworkInfo.java 类中，您会看到网络详细状态被声明为 Enum，

public enum DetailedState {
        /** Ready to start data connection setup. */
        IDLE,
        /** Searching for an available access point. */
        SCANNING,
        /** Currently setting up data connection. */
        CONNECTING,
        /** Network link established, performing authentication. */
        AUTHENTICATING,
        /** Awaiting response from DHCP server in order to assign IP address information. */
        OBTAINING_IPADDR,
        /** IP traffic should be available. */
        CONNECTED,
        /** IP traffic is suspended */
        SUSPENDED,
        /** Currently tearing down data connection. */
        DISCONNECTING,
        /** IP traffic not available. */
        DISCONNECTED,
        /** Attempt to connect failed. */
        FAILED,
        /** Access to this network is blocked. */
        BLOCKED,
        /** Link has poor connectivity. */
        VERIFYING_POOR_LINK,
        /** Checking if network is a captive portal */
        CAPTIVE_PORTAL_CHECK
    }

但是如果你阅读了这些 DetailedState 的评论，它会在下面说明这些

The fine-grained state of a network connection. This level of detail is probably of interest to few applications. Most should use android.net.NetworkInfo.State State instead.

NetworkInfo.java 类中的 isConnected() 方法仅检查 State.CONNECTED State，

public boolean isConnected() {
        synchronized (this) {
            return mState == State.CONNECTED;
        }
    }

基本上如果你使用

NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
boolean isConnected = activeNetwork != null &&
                      activeNetwork.isConnectedOrConnecting();

这应该足够了，因为上面的代码将查询 Activity 网络并确定它是否具有 Internet 连接。一旦知道，您就可以继续访问互联网资源。