从数据库中获取列表并在 Listview 中显示需要很长时间

Question

在我的应用程序中，我在我的数据库中存储了 8 个静态 dns 字段。这只是一个名称值对。单击按钮时，我将存储在数据库中的名称和 IP 地址获取到数组列表中，并使用基本适配器在列表视图中显示它们。一切正常，但按下按钮后几乎需要 4-5 秒才能显示 listview 。 这个时间是正常的还是应该更少？此外，我还从代码的其他部分添加该列表中的项目，因此每次我必须再次从数据库中获取列表时单击按钮。 如果这个时间更多，如果不是，我该怎么做才能减少这个时间？？

这是在按钮单击时运行的代码

public void LoadPrimaryDnsList(){

    dnsName=dataBaseHelper.getDnsName();
    ipAddress=dataBaseHelper.getIpAddress();
    id=dataBaseHelper.getId();
    dnsListAdapter = new DnsListAdapter(getActivity(), dnsName, ipAddress,id);
    dnsListAdapter.notifyDataSetChanged();
    android.support.v7.app.AlertDialog.Builder builder;
    final android.support.v7.app.AlertDialog alertDialog;
    LayoutInflater inflater = getActivity().getLayoutInflater();
    View layout = inflater.inflate(R.layout.browse_dns_dialog, (ViewGroup) getActivity().findViewById(R.id.lin_dialog));
    listView = (ListView) layout.findViewById(R.id.dns_list);

    builder = new android.support.v7.app.AlertDialog.Builder(getActivity());
    builder.setView(layout);
    alertDialog = builder.create();

    alertDialog.show();
    listView.setAdapter(dnsListAdapter);
    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            String ip = ipAddress.get(position);
            EDITDNS1.setText(ip);
            alertDialog.dismiss();
        }

    });
}

这是适配器类

public class DnsListAdapter extends BaseAdapter {
    Context context;

    LayoutInflater layoutInflater;

    ArrayList<String> dnslist=new ArrayList<>();
    ArrayList<String> iplist=new ArrayList<>();
    ArrayList<String> ids=new ArrayList<>();
    public DnsListAdapter(Context context, ArrayList<String> dns, ArrayList<String> ip,ArrayList<String> id) {
        this.context = context;
        dnslist=dns;
        iplist=ip;
        ids=id;
        layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public int getCount() {
        return dnslist.size();
    }

    @Override
    public Object getItem(int position) {
        return null;
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;
        if (convertView == null) {
            holder = new ViewHolder();
            convertView = layoutInflater.inflate(R.layout.dialog_row, parent, false);
            holder.tv_name = (TextView) convertView.findViewById(R.id.dnsName);
            holder.tv_ip= (TextView) convertView.findViewById(R.id.ip_address);
            holder.iv_cross= (ImageView) convertView.findViewById(R.id.iv_cross);
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        holder.tv_name.setText(dnslist.get(position));
        if (holder.tv_name.getText().toString().equalsIgnoreCase("Google 1")||holder.tv_name.getText().toString().equalsIgnoreCase("Google 2")||holder.tv_name.getText().toString().equalsIgnoreCase("Level3 1")
                ||holder.tv_name.getText().toString().equalsIgnoreCase("Level3 2")||holder.tv_name.getText().toString().equalsIgnoreCase("DNS Watch 1")||holder.tv_name.getText().toString().equalsIgnoreCase("DNS Watch 2")
                ||holder.tv_name.getText().toString().equalsIgnoreCase("OpenDNS 1")||holder.tv_name.getText().toString().equalsIgnoreCase("OpenDNS 2"))
        {
            holder.iv_cross.setVisibility(View.INVISIBLE);
        }
        holder.tv_ip.setText(iplist.get(position));
        Fonts.setHelveticaFont(getActivity(), holder.tv_name);
        Fonts.setHelveticaFont(getActivity(), holder.tv_ip);
        holder.iv_cross.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                dataBaseHelper.deleteRow(id.get(position));
                dnsName.remove(position);
                ipAddress.remove(position);
                id.remove(position);
                dnsListAdapter.notifyDataSetChanged();

            }
        });
        return convertView;
    }

}

Answer 1

我建议您加载数据并使用AsyncTask 异步填充ListView。

Answer 2

如果你想要速度，你应该预先加载所有的东西。

@Override
public void onCreate(Bundle s) {
    dnsName=dataBaseHelper.getDnsName();
    ipAddress=dataBaseHelper.getIpAddress();
    id=dataBaseHelper.getId();
    dnsListAdapter = new DnsListAdapter(getActivity(), dnsName, ipAddress,id);
    dnsListAdapter.notifyDataSetChanged();
    android.support.v7.app.AlertDialog.Builder builder;
    final android.support.v7.app.AlertDialog alertDialog;
    LayoutInflater inflater = getActivity().getLayoutInflater();
    View layout = inflater.inflate(R.layout.browse_dns_dialog, (ViewGroup) getActivity().findViewById(R.id.lin_dialog));
    listView = (ListView) layout.findViewById(R.id.dns_list);

    builder = new android.support.v7.app.AlertDialog.Builder(getActivity());
    builder.setView(layout);
    alertDialog = builder.create();

    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            String ip = ipAddress.get(position);
            EDITDNS1.setText(ip);
            alertDialog.dismiss();
        }

    });
}

public void LoadPrimaryDnsList(){
    alertDialog.show();
    listView.setAdapter(dnsListAdapter);
}

除此之外，如果你想了解你的代码的速度，你应该开始添加一些计时日志http://developer.android.com/reference/android/util/TimingLogger.html

另外，为了使您的代码更具可读性（并且更易于扩展/增强），我将开始了解 Single Responsibility Principle 并将其应用到您的方法中。