DBHelper 类遵循 Respsitory 模式。对底层数据的访问包含在“存储库”类中。这释放了您的主要逻辑以专注于业务逻辑并将所有数据处理责任推到存储库中。根据您的应用程序的复杂性，存储库可能充当“门面”，其中调用被简单地代理到负责域对象的存储库。
下面的代码为 DBHelper 创建了一个非常简单的模板
public class DBHelper
{
Context context;
private SQLiteDatabase db;
private final String DB_NAME = "MYDataBase";
private final int DB_VERSION = 1;
private final String TABLE_NAME = "Animal";
private final String TABLE_ROW_ID = "id";
private final String TABLE_ROW_ONE = "animal_name";
private final String TABLE_ROW_TWO = "animal_bio";
public DBHelper(Context context)
{
this.context = context;
CustomSQLiteOpenHelper helper = new CustomSQLiteOpenHelper(context);
this.db = helper.getWritableDatabase();
}
public static byte[] getBitmapAsByteArray(Bitmap bitmap)
{
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
bitmap.compress(CompressFormat.PNG, 0, outputStream);
return outputStream.toByteArray();
}
public void addRow(String name, String bio)
{
ContentValues values = new ContentValues();
values.put(TABLE_ROW_ONE, name);
values.put(TABLE_ROW_TWO, bio);
try
{
db.insert(TABLE_NAME, null, values);
Log.w("database message","Insert successfully");
}
catch(Exception e)
{
Log.e("DB ERROR", e.toString());
//e.printStackTrace();
}
}
public void deleteRow(long rowID)
{
try
{
db.delete(TABLE_NAME, TABLE_ROW_ID + "=" + rowID, null);
Log.w("database message","delete successfully");
}
catch (Exception e)
{
Log.e("DB ERROR", e.toString());
e.printStackTrace();
}
}
public void updateRow(long rowID,String name,String bio)
{
ContentValues values = new ContentValues();
values.put(TABLE_ROW_ONE, name);
values.put(TABLE_ROW_TWO, bio);
try
{
db.update(TABLE_NAME, values, TABLE_ROW_ID + "=" + rowID, null);
Log.w("database message","Update successfully");
}
catch (Exception e)
{
Log.e("DB Error", e.toString());
e.printStackTrace();
}
}
public int count_row()
{
int row=0;
Cursor cursor;
try
{
cursor = db.query(
TABLE_NAME,
new String[]{TABLE_ROW_ID, TABLE_ROW_ONE, TABLE_ROW_TWO},
null, null, null, null, null
);
cursor.moveToFirst();
if (!cursor.isAfterLast())
{
do
{
row++;
}
while (cursor.moveToNext());
}
}
catch (SQLException e)
{
Log.e("DB Error", e.toString());
e.printStackTrace();
}
Log.w("row count..",""+row);
return row;
}
public void getRow(long rowID)
{
Cursor cursor;
try
{
cursor = db.query
(
TABLE_NAME,
new String[] { TABLE_ROW_ID, TABLE_ROW_ONE, TABLE_ROW_TWO},
TABLE_ROW_ID + "=" + rowID,
null, null, null, null, null
);
cursor.moveToFirst();
if (!cursor.isAfterLast())
{
do
{
Log.w("row ",""+cursor.getLong(0));
Log.w("row ",""+cursor.getString(1));
Log.w("row ",""+cursor.getFloat(2));
}
while (cursor.moveToNext());
}
cursor.close();
}
catch (SQLException e)
{
Log.e("DB ERROR", e.toString());
e.printStackTrace();
}
}
public void getAllRows()
{
int i=0;
Cursor cursor;
try
{
cursor = db.query(
TABLE_NAME,
new String[]{TABLE_ROW_ID, TABLE_ROW_ONE, TABLE_ROW_TWO},
null, null, null, null, null
);
cursor.moveToFirst();
if (!cursor.isAfterLast())
{
do
{
Log.w("row "+i,""+cursor.getLong(0));
Log.w("row "+i,""+cursor.getString(1));
Log.w("row "+i,""+cursor.getFloat(2));
i++;
}
while (cursor.moveToNext());
}
}
catch (SQLException e)
{
Log.e("DB Error", e.toString());
e.printStackTrace();
}
}
private class CustomSQLiteOpenHelper extends SQLiteOpenHelper
{
public CustomSQLiteOpenHelper(Context context)
{
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
String newTableQueryString = "create table " +
TABLE_NAME +
" (" +
TABLE_ROW_ID + " integer primary key autoincrement not null," +
TABLE_ROW_ONE + " text," +
TABLE_ROW_TWO + " text" +
");";
db.execSQL(newTableQueryString);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
}
}
}
公共无效 onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
DBHelper database = new DBHelper(this);
database.addRow("name1","bio1");
database.addRow("name2","bio2");
database.addRow("name3","bio3");
database.addRow("name4","bio4");
database.addRow("name5","bio5");
database.getAllRows();
database.updateRow(2,"name20","bio20");
database.getAllRows();
database.deleteRow(2);
database.getAllRows();
}
更多详细信息
http://mel-tools.mit.edu/code/SimpleContentProvider/doc/edu/mit/mobile/android/content/class-use/DBHelper.html
在您的应用程序中复制 DBHelper 类我希望它有用.....