Question

我正在尝试使用预先填充了数据的多个表的数据库。在所有表格的一列中有一份饮料清单。我想把这个饮料列表放到我活动的ListView中。我在ListView上查找了Vogel的网站，我还阅读了一本书中的教程，我基本上复制了代码，我还阅读了Fluxa关于使用自己的数据库的教程。我不知道我的代码是否不正确，但它不会加载我正在寻找的饮料列表。有人可以查看我的代码，并可能指出我可能遗漏或没有看到的任何错误吗？

HotEspresso.java

public class HotEspresso extends ListActivity {

    private DrinkDbAdapter mDbHelper;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.hot_espresso);
        mDbHelper = new DrinkDbAdapter(this);
        mDbHelper.openToRead();
        fillData();
        }

    private void fillData() {
        Cursor drinkCursor  = mDbHelper.getHotTitles();
        startManagingCursor(drinkCursor);

        String[] from = new String[]{DrinkDbAdapter.KEY_DRINK};
        int[] to = new int[] {R.id.hot_espresso_row};
        SimpleCursorAdapter drinks = new SimpleCursorAdapter(this, R.layout.hot_espresso_list, drinkCursor, from, to);
        setListAdapter(drinks);

    }
}

DrinkDbAdapter.java

public class DrinkDbAdapter extends Activity {
private static final String DATABASE_NAME = "drinks";
private static final String DATABASE_TABLE_HOT = "hot";
private static final String DATABASE_TABLE_COFFEE = "coffee";
private static final String DATABASE_TABLE_HOTTEA = "hottea";
private static final String DATABASE_TABLE_COLD = "cold";
private static final String DATABASE_TABLE_BLENDED = "blended";
private static final String DATABASE_TABLE_COLDTEA = "coldtea";
private static final int DATABASE_VERSION = 1;

public static final String KEY_ROWID = "_id";
public static final String KEY_DRINK = "drink";
public static final String KEY_CATEGORY = "category";
public static final String KEY_LIQUID = "liquid";
public static final String KEY_LIQUID_AMOUNT = "liquid_amount";
public static final String KEY_POWDER = "powder";
public static final String KEY_POWDER_AMOUNT = "powder_amount";
public static final String KEY_SHOTS = "shots";
public static final String KEY_ADDITIVE1 = "add1";
public static final String KEY_ADDITIVE1_AMOUNT = "add1_amount";
public static final String KEY_ADDITIVE2 = "add2";
public static final String KEY_ADDITIVE2_AMOUNT = "add2_amount";

private static final String TAG = "DrinkDbAdapter";
private DatabaseHelper myDbHelper;
private SQLiteDatabase myDbDrinks;

private static final String DATABASE_CREATE_HOT =
        "create table " + DATABASE_TABLE_HOT + " (" + KEY_ROWID
        + " integer primary key autoincrement, " + KEY_DRINK + " text not null, " 
        + KEY_CATEGORY + " text not null, " + KEY_LIQUID + " text not null, "
        + " text not null, " + KEY_LIQUID_AMOUNT + " text not null, " 
        + KEY_POWDER + " text not null, " + KEY_POWDER_AMOUNT
        + " text not null, " + KEY_SHOTS + " text not null, " + KEY_ADDITIVE1
        + " text not null, " + KEY_ADDITIVE1_AMOUNT + " text not null, " 
        + KEY_ADDITIVE2 + " text not null, " + KEY_ADDITIVE2_AMOUNT + " text not null);"; 
private static final String DATABASE_CREATE_COFFEE =
        "create table " + DATABASE_TABLE_COFFEE + " (" + KEY_ROWID
        + " integer primary key autoincrement, " + KEY_DRINK + " text not null, " 
        + KEY_CATEGORY + " text not null, " + KEY_LIQUID + " text not null, "
        + " text not null, " + KEY_LIQUID_AMOUNT + " text not null, " 
        + KEY_POWDER + " text not null, " + KEY_POWDER_AMOUNT
        + " text not null, " + KEY_SHOTS + " text not null, " + KEY_ADDITIVE1
        + " text not null, " + KEY_ADDITIVE1_AMOUNT + " text not null, " 
        + KEY_ADDITIVE2 + " text not null, " + KEY_ADDITIVE2_AMOUNT + " text not null);";
private static final String DATABASE_CREATE_HOTTEA =
        "create table " + DATABASE_TABLE_HOTTEA + " (" + KEY_ROWID
        + " integer primary key autoincrement, " + KEY_DRINK + " text not null, " 
        + KEY_CATEGORY + " text not null, " + KEY_LIQUID + " text not null, "
        + " text not null, " + KEY_LIQUID_AMOUNT + " text not null, " 
        + KEY_POWDER + " text not null, " + KEY_POWDER_AMOUNT
        + " text not null, " + KEY_SHOTS + " text not null, " + KEY_ADDITIVE1
        + " text not null, " + KEY_ADDITIVE1_AMOUNT + " text not null, " 
        + KEY_ADDITIVE2 + " text not null, " + KEY_ADDITIVE2_AMOUNT + " text not null);";
private static final String DATABASE_CREATE_COLD =
        "create table " + DATABASE_TABLE_COLD + " (" + KEY_ROWID
        + " integer primary key autoincrement, " + KEY_DRINK + " text not null, " 
        + KEY_CATEGORY + " text not null, " + KEY_LIQUID + " text not null, "
        + " text not null, " + KEY_LIQUID_AMOUNT + " text not null, " 
        + KEY_POWDER + " text not null, " + KEY_POWDER_AMOUNT
        + " text not null, " + KEY_SHOTS + " text not null, " + KEY_ADDITIVE1
        + " text not null, " + KEY_ADDITIVE1_AMOUNT + " text not null, " 
        + KEY_ADDITIVE2 + " text not null, " + KEY_ADDITIVE2_AMOUNT + " text not null);";
private static final String DATABASE_CREATE_BLENDED =
        "create table " + DATABASE_TABLE_BLENDED + " (" + KEY_ROWID
        + " integer primary key autoincrement, " + KEY_DRINK + " text not null, " 
        + KEY_CATEGORY + " text not null, " + KEY_LIQUID + " text not null, "
        + " text not null, " + KEY_LIQUID_AMOUNT + " text not null, " 
        + KEY_POWDER + " text not null, " + KEY_POWDER_AMOUNT
        + " text not null, " + KEY_SHOTS + " text not null, " + KEY_ADDITIVE1
        + " text not null, " + KEY_ADDITIVE1_AMOUNT + " text not null, " 
        + KEY_ADDITIVE2 + " text not null, " + KEY_ADDITIVE2_AMOUNT + " text not null);";
private static final String DATABASE_CREATE_COLDTEA =
        "create table " + DATABASE_TABLE_COLDTEA + " (" + KEY_ROWID
        + " integer primary key autoincrement, " + KEY_DRINK + " text not null, " 
        + KEY_CATEGORY + " text not null, " + KEY_LIQUID + " text not null, "
        + " text not null, " + KEY_LIQUID_AMOUNT + " text not null, " 
        + KEY_POWDER + " text not null, " + KEY_POWDER_AMOUNT
        + " text not null, " + KEY_SHOTS + " text not null, " + KEY_ADDITIVE1
        + " text not null, " + KEY_ADDITIVE1_AMOUNT + " text not null, " 
        + KEY_ADDITIVE2 + " text not null, " + KEY_ADDITIVE2_AMOUNT + " text not null);";

private final Context mCtx;

private static class DatabaseHelper extends SQLiteOpenHelper {

    //The Android's default system path of your application database.
    private static String DB_PATH = "/data/data/com.miskitup.CoffeeNutrition/databases/";
    private static String DB_NAME = "drinks";
    private SQLiteDatabase myDataBase; 
    private final Context myContext;

    //Constructor
    //Takes and keeps a reference of the passed context in order to access to the application assets and resources.
    //@param context

    DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        this.myContext = context;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(DATABASE_CREATE_HOT);
        db.execSQL(DATABASE_CREATE_COFFEE);
        db.execSQL(DATABASE_CREATE_HOTTEA);
        db.execSQL(DATABASE_CREATE_COLD);
        db.execSQL(DATABASE_CREATE_BLENDED);
        db.execSQL(DATABASE_CREATE_COLDTEA);
    }

    @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 notes");
        onCreate(db);
    }

     //Creates a empty database on the system and rewrites it with your own database.

    public void createDataBase() throws IOException{
        boolean dbExist = checkDataBase();
        if(dbExist){
            //do nothing - database already exist
        }else{

            //By calling this method and empty database will be created into the default system path
               //of your application so we are gonna be able to overwrite that database with our database.
            this.getReadableDatabase();
            try {
                copyDataBase();
            } catch (IOException e) {
                throw new Error("Error copying database");
            }
        }

    }

    //Check if the database already exist to avoid re-copying the file each time you open the application.
    //@return true if it exists, false if it doesn't

    private boolean checkDataBase(){
        SQLiteDatabase checkDB = null;
        try{
            String myPath = DB_PATH + DB_NAME;
            checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
        }catch(SQLiteException e){

            //database doesn't exist yet.

        }

        if(checkDB != null){
            checkDB.close();
        }

        return checkDB != null ? true : false;
    }



    //Copies your database from your local assets-folder to the just created empty database in the
    //system folder, from where it can be accessed and handled.
    //This is done by transfering bytestream.

    private void copyDataBase() throws IOException{

        //Open your local db as the input stream
        InputStream myInput = myContext.getAssets().open(DB_NAME);

        // Path to the just created empty db
        String outFileName = DB_PATH + DB_NAME;

        //Open the empty db as the output stream
        OutputStream myOutput = new FileOutputStream(outFileName);

        //transfer bytes from the inputfile to the outputfile
        byte[] buffer = new byte[1024];
        int length;
        while ((length = myInput.read(buffer))>0){
            myOutput.write(buffer, 0, length);
        }

        //Close the streams
        myOutput.flush();
        myOutput.close();
        myInput.close();

    }

    public void openDataBase() throws SQLException{
        //Open the database
        String myPath = DB_PATH + DB_NAME;
        myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

    }

    @Override
    public synchronized void close() {
            if(myDataBase != null)
                myDataBase.close();
            super.close();
    }

        // Add your public helper methods to access and get content from the database.
       // You could return cursors by doing "return myDataBase.query(....)" so it'd be easy
       // to you to create adapters for your views.

}

public DrinkDbAdapter(Context ctx) {
    this.mCtx = ctx;
}

public DrinkDbAdapter openToRead() throws android.database.SQLException {
    myDbHelper = new DatabaseHelper(mCtx);
    myDbDrinks = myDbHelper.getReadableDatabase();
    return this;
}

public DrinkDbAdapter openToWrite() throws android.database.SQLException {
    myDbHelper = new DatabaseHelper(mCtx);
    myDbDrinks = myDbHelper.getWritableDatabase();
    return this;
}

public void close() {
    myDbHelper.close();
}

public Cursor getTitle(long rowId, String table) throws SQLException {
    Cursor mCursor =myDbDrinks.query(true, table, new String[] {KEY_ROWID, KEY_DRINK, KEY_LIQUID, KEY_LIQUID_AMOUNT,
    KEY_POWDER, KEY_POWDER_AMOUNT, KEY_SHOTS, KEY_ADDITIVE1, KEY_ADDITIVE1_AMOUNT, KEY_ADDITIVE2, KEY_ADDITIVE2_AMOUNT},
    KEY_ROWID + "=" + rowId, null, null, null, null, null);
        if (mCursor != null) {
            mCursor.moveToFirst();
        }
        return mCursor;
    }

public Cursor getHotTitles() {
    return myDbDrinks.query(DATABASE_TABLE_HOT, new String[] {KEY_ROWID, KEY_DRINK}, null, null, null, null, null);
}

}

hot_espresso.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" 
    android:orientation="vertical">
    <ListView android:id="@+id/android:list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#e9ddc8"
        android:divider="#44059f"
        android:dividerHeight="1dp"
        android:cacheColorHint="#e9ddc8" />
        <TextView android:id="@+id/android:empty"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
</LinearLayout>

hot_espresso_list.xml

<?xml version="1.0" encoding="utf-8"?>
<TextView
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/hot_espresso_row"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:padding="10dp"
android:textColor="#44059f" />

非常感谢任何想法或建议。

Answer 1

private static final String DATABASE_CREATE_HOT =
    "create table " + DATABASE_TABLE_HOT + " (" + KEY_ROWID
    + " integer primary key autoincrement, " + KEY_DRINK + " text not null, " 
    + KEY_CATEGORY + " text not null, " + KEY_LIQUID + " text not null, "
    + " text not null, " + KEY_LIQUID_AMOUNT + " text not null, " 
    + KEY_POWDER + " text not null, " + KEY_POWDER_AMOUNT
    + " text not null, " + KEY_SHOTS + " text not null, " + KEY_ADDITIVE1
    + " text not null, " + KEY_ADDITIVE1_AMOUNT + " text not null, " 
    + KEY_ADDITIVE2 + " text not null, " + KEY_ADDITIVE2_AMOUNT + " text not null);";

在KEY_LIQUID之后，有两次“text not null”。

列表不会从数据库信息创建

1 个答案: