如何在Java中检测网络连接状态 Java判断是否联网的方式

import java.net.InetAddress;
import java.net.UnknownHostException;

public class NetworkChecker {

    public static boolean isInternetAvailable() {
        try {
            InetAddress address = InetAddress.getByName("8.8.8.8"); // Google DNS
            return address.isReachable(1000); // Timeout of 1 second
        } catch (UnknownHostException e) {
            // Host not found (likely no internet)
            return false;
        } catch (Exception e) {
            // Other errors (e.g., timeout, security exception)
            return false;
        }
    }

    public static void main(String[] args) {
        if (isInternetAvailable()) {
            System.out.println("Internet is available.");
        } else {
            System.out.println("Internet is not available.");
        }
    }
}

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Arrays;
import java.util.List;

public class NetworkChecker {

    private static final List<String> TEST_HOSTS = Arrays.asList("8.8.8.8", "1.1.1.1", "baidu.com"); // Google DNS, Cloudflare DNS, Baidu

    public static boolean isInternetAvailable() {
        for (String host : TEST_HOSTS) {
            try {
                InetAddress address = InetAddress.getByName(host);
                if (address.isReachable(1000)) {
                    return true; // At least one host is reachable
                }
            } catch (UnknownHostException e) {
                // Host not found
            } catch (Exception e) {
                // Other errors
            }
        }
        return false; // None of the hosts are reachable
    }

    public static void main(String[] args) {
        if (isInternetAvailable()) {
            System.out.println("Internet is available.");
        } else {
            System.out.println("Internet is not available.");
        }
    }
}

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

public class AndroidNetworkChecker {

    public static boolean isNetworkAvailable(Context context) {
        ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        if (connectivityManager == null) {
            return false;
        }
        NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
        return networkInfo != null && networkInfo.isConnected();
    }

    public static void main(String[] args) {
        // 需要一个Context对象才能调用 isNetworkAvailable()
        // 在非Android环境下，这部分代码无法直接运行
        // 在Android应用中，可以在Activity或Service中调用
        // 例如：
        // Context context = this; // 获取当前的Context
        // if (isNetworkAvailable(context)) {
        //     System.out.println("Network is available.");
        // } else {
        //     System.out.println("Network is not available.");
        // }
    }
}