提高在 Android 上将 JSON 流存储到本地数据库的性能

Question

I am developing an application that (part of its functionality) is fetching a huge list of items from a server, in JSON format, and stores it in a local SQLite database. Since the JSON file is huge, I am using the Gson library to perform the fetch, otherwise the application crashes because there is not enough RAM. Therefore, my only option is to fetch the file as a stream.

The JSON file structure is similar to this:

{
  "items": [
    {
        "itemID": "id1",
        "itemName": "name1"
    },
    {
        "itemID": "id2",
        "itemName": "name2"
    }
  ]
}

My Java code to process the stream looks like this:

JsonReader reader = new JsonReader(url_buffered_reader);
reader.beginObject();

String itemId = null;
String itemName = null;

while (reader.hasNext()) {
    if (reader.nextName().equals("items")) {
        reader.beginArray();
        while (reader.hasNext()) {
            reader.beginObject();
            while (reader.hasNext()) {
                String name = reader.nextName();
                switch (name) {
                    case "itemID":
                        itemId = reader.nextString().trim();
                        break;
                    case "itemName":
                        itemName = reader.nextString().trim();
                        break;
                    default:
                        reader.skipValue();
                        break;
                }
            }
            reader.endObject();

            storeItemData(itemId, itemName);
        }
        reader.endArray();
    }
}

The function storeItemData(String id, String name) looks like this (it is in a class that extends SQLiteOpenHelper ):

public void storeItemData(String id, String name) {
    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();
    values.put("itemID", id);
    values.put("itemName", name);

    long newRowId = db.insertWithOnConflict(
            "items",
            null,
            values, SQLiteDatabase.CONFLICT_REPLACE);
}

The code is working fine. The data is successfully downloaded and stored. The problem is that the performance is not good. Is there a more efficient way to store the data, so that the performance is improved?

Answer 1

There is overhead associated with inserting a record into a database. Assuming the database is your bottleneck, you should be able to increase write performance by wrapping your inserts into a transaction.

1. Move SQLiteDatabase db = this.getWritableDatabase(); out of storeItemData .
2. Call db.beginTransaction(); before you begin inserting.
3. Call db.setTransactionSuccessful(); and then db.endTransaction(); after you are done inserting.
4. Be sure to catch any exceptions so you can gracefully handle any error that may result from an insert.