开启GPRS或WIFI网络连接

private boolean CheckNetwork() {
	boolean flag = false;
	ConnectivityManager cwjManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
	if (cwjManager.getActiveNetworkInfo() != null)
		flag = cwjManager.getActiveNetworkInfo().isAvailable();
	if (!flag) {
		Builder b = new AlertDialog.Builder(this).setTitle("没有可用的网络")
				.setMessage("请开启GPRS或WIFI网络连接");
		b.setPositiveButton("确定", new DialogInterface.OnClickListener() {
			public void onClick(DialogInterface dialog, int whichButton) {
				Intent mIntent = new Intent("/");
				ComponentName comp = new ComponentName(
						"com.android.settings",
						"com.android.settings.WirelessSettings");
				mIntent.setComponent(comp);
				mIntent.setAction("android.intent.action.VIEW");
				startActivity(mIntent);
			}
		}).setNeutralButton("取消", new DialogInterface.OnClickListener() {
			public void onClick(DialogInterface dialog, int whichButton) {
				dialog.cancel();
			}
		}).create();
		b.show();
	}

	return flag;
}

// 判断是否有网络连接
if (!CheckNetwork())
	return;