小记：判断设备是否联网！

记住加权限：

package com.lixu.getInternet;

import android.app.Activity;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.widget.Toast;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        boolean b = isConnect(this);

        if (b == true)
            Toast.makeText(this, "您的手机已经联网!", Toast.LENGTH_LONG).show();

        else if (b == false)
            Toast.makeText(this, "您的手机没有联网！", Toast.LENGTH_LONG).show();

    }

    public boolean isConnect(Context context) {
        ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        if (cm != null) {
            NetworkInfo info = cm.getActiveNetworkInfo();
            if (info != null && info.isConnected()) {
                if (info.getState() == NetworkInfo.State.CONNECTED) {
                    return true;
                }
            }
        }
        return false;
    }

}

运行效果：