从后台服务插入数据到sqlite数据库

Question

在我的应用程序中，我有一个DBAdapter类处理SQLite数据库。我想开始一个后台服务，从Web获取一些数据，并写入数据库。该服务是异步的。

请给出一个提示或一些参考如何使用后台服务和我的DBAdapter类异步地将数据写入我的数据库。提前致谢。

DBAdapter.java

public class DBAdapter { 
    // define tag 
    public static final String TAG = "DBAdapter"; 
    // define table fields 
    static final String KEY_ID = "_id"; 
    static final String KEY_NAME = "name"; 

    // define table names 
    static final String TABLE_INFO = "info"; 
    // define database name 
    static final String DATABASE_NAME = "test_db_debug"; 
    // define database version 
    static final int DATABASE_VERSION = 1; 
    // define separators 
    static final String COMMA_SEP = ", "; 
    static final String IPA_SEP = " integer primary key autoincrement "; 
    static final String INT_SEP = " integer"; 
    static final String TEXT_SEP = " TEXT"; 
    // define database creation queries 
    static final String CREATE_INFO = "create table " + TABLE_INFO + "(" 
              + KEY_ID + IPA_SEP + COMMA_SEP 
              + KEY_NAME + TEXT_SEP +")"; 

    final Context context; 
    DatabaseHelper DBHelper; 
    SQLiteDatabase db; 

    // Constructor. Creates database. 
    public DBAdapter(Context ctx) { 
     this.context = ctx; 
     // create database 
     DBHelper = new DatabaseHelper(context); 
    } 

    // ----- make private class ----- 
    private class DatabaseHelper extends SQLiteOpenHelper { 

     // constructor 
     DatabaseHelper(Context context) { 
      super(context, DATABASE_NAME, null, DATABASE_VERSION); 
      //Toast.makeText(context, "DatabaseHelper Constructor", Toast.LENGTH_LONG).show(); 
      Log.d(TAG, "DatabseHelper Constructor Loaded."); 
     } 

     @Override 
     public void onCreate(SQLiteDatabase db) { 
      // TODO Auto-generated method stub 
      // create databases 
      try { 
       db.execSQL(CREATE_INFO); 
       Log.d(TAG, "All tables has been created."); 
      } catch(Exception e) { 
       e.printStackTrace(); 
      } 
     } 

     @Override 
     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
      // TODO Auto-generated method stub 
      Log.d(TAG, "Updating database from version " + oldVersion + " to " + newVersion + 
        ", which will destroy all old data."); 
      String drp = "DROP TABLE IF EXISTS "; 

      db.execSQL(drp + TABLE_INFO); 

      onCreate(db); 
     } 
    } // ----- ends private class ------ 

    // --- opens the database --- 
    public DBAdapter open() { 
     db = DBHelper.getWritableDatabase(); 
     Log.d(TAG, "Database opened."); 
     return this; 
    } 

    // --- closes the database --- 
    public void close() { 
     DBHelper.close(); 
     Log.d(TAG, "Database closed."); 
    } 

    // get all data of table 
    public Cursor getAllData() { 
     return db.query(TABLE_INFO, new String[]{ KEY_ID, KEY_NAME }, null, null, null, null, null); 
    } 

    // insert data 
    public long insertData(int id, String name) { 
     ContentValues cv = new ContentValues(); 
     cv.put(KEY_ID, id); 
     cv.put(KEY_NAME, name); 
     return db.insert(TABLE_INFO, null, cv); 
    } 
} 

后台服务：

public class DownloadAllData extends Service { 

    @Override 
    public IBinder onBind(Intent arg0) { 
     // TODO Auto-generated method stub 
     return null; 
    } 

    @Override 
    public int onStartCommand(Intent intent, int flags, int startId) { 
     // TODO Auto-generated method stub"" 
     Log.d("DB", "Service Started"); 
     Toast.makeText(getBaseContext(), "Service Started", Toast.LENGTH_LONG) 
       .show(); 

     new DoBackgroundTask() 
       .execute(new String[] { 
         "http://192.168.2.7/orca_android_app/select_country.php?key=country", 
         "country","id", "name" }); 
     stopSelf(); 
     // return super.onStartCommand(intent, flags, startId); 
     return START_STICKY; 
    } 

    private class DoBackgroundTask extends AsyncTask<String, Void, String> { 
     String [] KEY; 

     @Override 
     protected String doInBackground(String... urls) { 
      // TODO Auto-generated method stub 
      KEY = urls; 
      Log.d("DB", urls[0]); 
      Log.d("DB", "length of urls: "+urls.length); 
      // Building Parameters 
      List<NameValuePair> params = new ArrayList<NameValuePair>(); 
      // getting JSON string from URL 
      JSONParser jParser = new JSONParser(); 
      JSONObject json = jParser.makeHttpRequest(urls[0], "GET", params); 
      return json.toString(); 
     } 

     @Override 
     protected void onPreExecute() { 
      // TODO Auto-generated method stub 
      super.onPreExecute(); 
     } 

     @Override 
     protected void onPostExecute(String result) { 
      // TODO Auto-generated method stub 
      try { 
       JSONObject jObject = new JSONObject(result); 
       JSONArray jsonArray = jObject.getJSONArray("result"); 

       for (int i = 0; i < jsonArray.length(); i++) { 
        JSONObject jsonObject = jsonArray.getJSONObject(i); 
        Log.d("DB", "in for: "+jsonObject.toString()); 

        ContentValues cv = new ContentValues(); 

        for(int j=2; j<KEY.length; j++) { 
         String str = jsonObject.getString(KEY[j]); 
         cv.put(KEY[j], str); 
         Log.d("DB", KEY[j]+": "+str); 
        } 
       } 
      } catch (Exception e) { 
       e.printStackTrace(); 
       Log.e("DB", "onPostExecute Error: " + e.getMessage()); 
      } 
     } 

    } 

    @Override 
    public void onDestroy() { 
     // TODO Auto-generated method stub 
     Log.d("DB", "Service Destroyed"); 
     super.onDestroy(); 
    } 
} 

Answer 1

，而不是分析上PostExecute（字符串结果）JSON阵列 解析数据上doinBackground线程并保存细节 上的PostExecute方法。

它认为它可以帮助ü