Question

我一直在研究一个Android应用程序，它读取大小约3MB的JSON文件，并在屏幕上显示一些数据。但是，加载需要花费大量时间，并且大部分时间用于生成包含整个文件的JSON对象。我已经看了几个基准测试，但是我远远不及标准JSON解析器的结果说我应该这么快。构建JSON对象大约需要20秒，代码如下所示。

private String obtainLeaderboardsData(String host) {
    StringBuilder builder = new StringBuilder();
    HttpClient client = new DefaultHttpClient();
    String URL = "http://" + host + "/api/wow/challenge/region?locale=en_GB";
    HttpGet httpGet = new HttpGet("http://eu.battle.net/api/wow/challenge/region?locale=en_GB");
    try {
        HttpResponse response = client.execute(httpGet);
        StatusLine statusLine = response.getStatusLine();
        int statusCode = statusLine.getStatusCode();
        if (statusCode == 200) {
            HttpEntity entity = response.getEntity();
            InputStream content = entity.getContent();
            BufferedReader reader = new BufferedReader(new InputStreamReader(content));
            String line;
            while ((line = reader.readLine()) != null) {
                builder.append(line);
            }
        } else {
            Log.e(MainActivity.class.toString(), "Failed to download file");
        }
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return builder.toString();
}

private class LoadData extends AsyncTask<Void, Void, ArrayList<Run>> {

    @Override
    protected ArrayList<Run> doInBackground(Void... arg0) {
        ArrayList<Run> runs = new ArrayList<Run>();
        String[] hosts = {"eu.battle.net"};
        for(String host : hosts) {
            String leaderboardsData = obtainLeaderboardsData(host);
            try {   
                JSONObject leaderboard = new JSONObject(leaderboardsData);
                JSONArray challenges = leaderboard.getJSONArray("challenge");
                for(int i = 0; i < challenges.length(); i++) {
                    JSONObject challenge = challenges.getJSONObject(i);
                    JSONObject o_dungeon = challenge.getJSONObject("map");
                    String dungeon = o_dungeon.getString("name");
                    JSONArray groups = challenge.getJSONArray("groups");
                    for(int j = 0; j < groups.length(); j++) {
                        JSONObject group = groups.getJSONObject(j);
                        Run run = new Run(group, dungeon);
                        if(run.hours_passed > 0 && run.hours_passed < 72) {
                            runs.add(run);
                        }
                    }       
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        Collections.sort(runs, new CustomComparator());
        return runs;
    }

    @Override
    protected void onPostExecute(ArrayList<Run> runs) {         
        ListView allList = (ListView) findViewById(R.id.allList);
        ArrayList<HashMap<String, String>> list = new ArrayList<HashMap<String, String>>(runs.size());
        for (Run run : runs) {
            HashMap<String, String> item = new HashMap<String, String>();
            item.put("rank_dungeon_timer_passed", "#" + run.ranking + " " + run.dungeon + " " + run.timer + " (" + run.hours_passed + " hours ago)");
            String members = "";
            for(int i = 0; i < run.members.size(); i++) {
                members = members + run.members.get(i) + "\n";
            }
            item.put("members", members);
            list.add(item);
        }
        String[] from = new String[] {"rank_dungeon_timer_passed", "members"};
        int[] to = new int[] {android.R.id.text1, android.R.id.text2};
        int nativeLayout = android.R.layout.two_line_list_item;
        allList.setAdapter(new SimpleAdapter(MainActivity.this, list, nativeLayout , from, to));
    }
}

花费时间最长的行是：

JSONObject leaderboard = new JSONObject(leaderboardsData);

这是一个在完整的JSON文件中读取的错误方法吗？

编辑：由于我没有使用大部分数据，我是否可以通过网址查询添加参数来过滤掉一些我不需要的字段？

Answer 1

我猜它正在解析那个电话中的信息而不是你需要的信息。我通过Jackson完成了所有JSON解析。它设置起来非常快速和简单。如果你有时间测试它，它可能会让你的生活从现在开始变得更容易。

加快Android中的JSON文件解析速度

1 个答案: