有网没网2

//判断

if(isNetworkConnected(MainActivity.this))
{

        Toast.makeText(MainActivity.this,"请求数据",Toast.LENGTH_SHORT).show();
        initView();
        initData();
        mAdapter = new MyAdapter(mContext,mList);
        mlv.setAdapter(mAdapter);
        new MyTask().execute(mUrl);

    }else{
        Toast.makeText(MainActivity.this,"没有联网,从数据库请求数据",Toast.LENGTH_SHORT).show();
    }

//定义一个方法
public boolean isNetworkConnected(Context context) {

    if (context != null) {
        ConnectivityManager mConnectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo mNetworkInfo = mConnectivityManager.getActiveNetworkInfo();
        if (mNetworkInfo != null) {
            return mNetworkInfo.isAvailable();
        }
    }
    return false;
}