Android判断wifi或者gprs是否连接

需要权限：

<!-- 访问网络权限 -->
<uses-permission android:name="android.permission.INTERNET" />
<!-- 检测网络状态权限 -->
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

package com.example.zhangying.wifidemo2;

import android.app.AlertDialog;
import android.content.ComponentName;
import android.content.DialogInterface;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Build;
import android.provider.Settings;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private boolean isConnected = false;
    private ConnectivityManager connectManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //1.得到网络连接信息
        connectManager = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);
        //2.判断网络是否连接
        if (connectManager.getActiveNetworkInfo() != null) {
            isConnected = connectManager.getActiveNetworkInfo().isConnected();
        }

        if (isConnected) {
            //网络已经连接，判断是wifi连接还是GPRS连接
            isWifiOrGPRS();
        } else {
            openNetWork();
        }

    }
    

    private void isWifiOrGPRS() {
        //获得wifi状态state
        NetworkInfo.State wifi_state = connectManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState();
        //获得gprs状态
        NetworkInfo.State gprs_state = connectManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState();
        if (wifi_state == NetworkInfo.State.CONNECTED || wifi_state == NetworkInfo.State.CONNECTING) {
            Toast.makeText(this, "wifi open!", Toast.LENGTH_SHORT).show();
        } else if (gprs_state == NetworkInfo.State.CONNECTED || gprs_state == NetworkInfo.State.CONNECTING) {
            Toast.makeText(this, "gprs open!", Toast.LENGTH_SHORT).show();
        }
    }

    private void openNetWork() {

        AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
        builder.setTitle("网络连接");
        builder.setMessage("当前网络不可用，请设置网络!");
        builder.setPositiveButton("设置", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                Intent intent = null;
                /**
                 * 若API>=10
                 */
                if (Build.VERSION.SDK_INT > 10) {
                    intent = new Intent(Settings.ACTION_WIFI_SETTINGS);
                } else {
                    /**
                     * 若API<10
                     */
                    intent = new Intent();
                    ComponentName componentName = new ComponentName("com.android.settings", "com.android.settings.WirelessSettings");
                    intent.setComponent(componentName);
                    intent.setAction("android.intent.action.VIEW");
                }
                startActivity(intent);
            }
        });
        builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {

            }
        });
        builder.create().show();
    }


}