Question

我试图创建一个从sql server获取数据并在listview中显示的应用程序，但我也想在sqlite数据库中保存json。为此我创建了以下SqliteDB类，但我对如何将json数据发送到此类感到困惑。

public class SqliteDB {

    public static final String KEY_ID = "id";
    public static final String KEY_NAME = "name";

    private static final String TAG = "DBAdapter";
    private static final String DATABASE_NAME = "SQLiteDB";

    private static final String TABLE_NAME = "departmentList";
    private static final int DATABASE_VERSION = 1;

    private static final String CREATE_TABLE = 
            "create table departmentList (id text primary key autoincrement, name text not null);";

    private final Context context;
    private DatabaseHelper DBHelper;
    private SQLiteDatabase db;


    public SqliteDB(Context ctx) {

        this.context = ctx;
        DBHelper = new DatabaseHelper(context);
    }
    private static class DatabaseHelper extends SQLiteOpenHelper {
        DatabaseHelper(Context context) {           
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

        @Override
        public void onCreate(SQLiteDatabase db) {           
            try {
                    db.execSQL(CREATE_TABLE);
                } catch (SQLException e) {
                    e.printStackTrace();
                }
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {      
            Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
                    + newVersion + ", which will destroy all old data");
            db.execSQL("DROP TABLE IF EXISTS sample");
            onCreate(db);
            }
        }

  //---open SQLite DB---
    public SqliteDB open() throws SQLException {    
        db = DBHelper.getWritableDatabase();
        return this;
    }

    //---close SQLite DB---
    public void close() {   
        DBHelper.close();
    }

    //---insert data into SQLite DB---
    public long insert(String name) {
        ContentValues initialValues = new ContentValues();
        initialValues.put(KEY_NAME, name);      
        return db.insert(TABLE_NAME, null, initialValues);
    }

    //---Delete All Data from table in SQLite DB---
    public void deleteAll() {
        db.delete(TABLE_NAME, null, null);
    }

    //---Get All Contacts from table in SQLite DB---
    public Cursor getAllData() {
        return db.query(TABLE_NAME, new String[] {KEY_NAME}, 
                null, null, null, null, null);
    }

}

接收json响应的类

public class DeptActivity extends Activity{


ArrayAdapter<String> adapter;
ListView listv;
Context context;
ArrayList<String> data;
SqliteDB sqlite;


@Override
protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_dept);

      sqlite = new SqliteDB(DeptActivity.this);
      setupActionBar();
      data = new ArrayList<String>();
      listv = (ListView) findViewById(R.id.lv_dept);
      context = this;

      adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, data);
      listv.setAdapter(adapter);
      Toast.makeText(this,"Loading Please Wait..",Toast.LENGTH_SHORT).show();
      new AsyncLoadDeptDetails().execute();

}

公共类AsyncLoadDeptDetails扩展的AsyncTask＆GT; { ArrayList deptTable = null;

      @Override
      public ArrayList<DeptTable> doInBackground(Void... params) {
            // TODO Auto-generated method stub

            RestAPI api = new RestAPI();
            try {
                   JSONObject jsonObj = api.GetDepartmentDetails();
                   JSONParser parser = new JSONParser();
                   Log.i( "department list", jsonObj.toString()); 
                   deptTable = parser.parseDepartment(jsonObj);
                   sqlite();

            } catch (Exception e) {
            }
      return deptTable;
  }

   //method to insert data json in sqlite
     private void sqlite() {
        // TODO Auto-generated method stub

        sqlite.open();
    for(int i=0; i<deptTable.size(); i++) {

            sqlite.insert(deptTable.get(i).toString());

        }

        sqlite.close();
    }   

      @Override
      protected void onPostExecute(ArrayList<DeptTable> result) {
            // TODO Auto-generated method stub

            for (int i = 0; i < result.size(); i++) {
                  data.add(result.get(i).getNo() + " " + result.get(i).getName());
            }

            adapter.notifyDataSetChanged();

            Toast.makeText(context,"Loading Completed",Toast.LENGTH_SHORT).show();
      }

Logcat错误

Error inserting name=com.example.db_client.DeptTable@b3e53870
android.database.sqlite.SQLiteException: no such table: departmentList (code 1): , while compiling: INSERT INTO departmentList(name) VALUES (?)
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java:1467)
at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1339)
at com.example.db_client.SqliteDB.insert(SqliteDB.java:73)
at com.example.db_client.DeptActivity$AsyncLoadDeptDetails.sqlite(DeptActivity.java:91)
at com.example.db_client.DeptActivity$AsyncLoadDeptDetails.doInBackground(DeptActivity.java:68)
at com.example.db_client.DeptActivity$AsyncLoadDeptDetails.doInBackground(DeptActivity.java:1)

Answer 1

我怀疑没有调用SQLiteOpenHelper的onCreate方法。这就是为什么没有创建数据库表的原因。请在您的DatabaseHelper的onCreate中登录并检查它是否正在打印。还可以尝试将SQLiteOpenHelper用作非静态内部类，即删除SQLiteDB类并直接使用DatabaseHelperClass构造函数。

Answer 2

public void onCreate(SQLiteDatabase db) {           
    try {
        db.execSQL(CREATE_TABLE);
    } catch (SQLException e) {
        e.printStackTrace();
    }
}

问题是你的CREATE_TABLE语句有错误，但你的onCreate函数抑制了这个错误，因此SQLiteOpenHelper认为它成功，并且数据库可用。

删除try / catch，然后移除您应用的数据（强制onCreate再次执行）。然后修复错误消息中的错误。

android：如何将数据从sql server保存到android的sqlite数据库

2 个答案: