Android网络状态判断

package com.syuct.heguicun.netconnection;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getNetInfor();
}
public void getNetInfor() {
//首先是获取网络连接管理者
ConnectivityManager manager = (ConnectivityManager)
getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo info = manager.getActiveNetworkInfo();
//网络状态存在并且是已连接状态
if (info != null && info.isConnected()) {
Toast.makeText(MainActivity.this, "网络已连接", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(MainActivity.this, "网络连接失败", Toast.LENGTH_SHORT).show();
//下面的这种写法你应该看得懂
new AlertDialog.Builder(MainActivity.this)
.setTitle("请检查网络连接")
.setNegativeButton("确定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
if (android.os.Build.VERSION.SDK_INT > 10) {
//安卓系统3.0以上打开设置界面，也可以直接用ACTION_WIRELESS_SETTINGS打开到wifi界面
startActivity(new Intent(android.provider.Settings.ACTION_SETTINGS));
} else {
startActivity(new Intent(android.provider.Settings.ACTION_WIRELESS_SETTINGS));
}
}
})
.show();
}
}
}