这是我如何实现此目标的示例。
在这个例子中，我会
store，
retrieve，
update和
delete一个学生的名字和年龄。
首先创建一个类，我叫我的
DBManager.java
public class DBManager { private Context context; private SQLiteDatabase database; private SQLiteHelper dbHelper; public DBManager(Context c) { this.context = c; } public DBManager open() throws SQLException { this.dbHelper = new SQLiteHelper(this.context); this.database = this.dbHelper.getWritableDatabase(); return this; } public void close() { this.dbHelper.close(); } public void insert(String name, String desc) { ContentValues contentValue = new ContentValues(); contentValue.put(SQLiteHelper.NAME, name); contentValue.put(SQLiteHelper.AGE, desc); this.database.insert(SQLiteHelper.TABLE_NAME_STUDENT, null, contentValue); } public Cursor fetch() { Cursor cursor = this.database.query(SQLiteHelper.TABLE_NAME_STUDENT, new String[]{SQLiteHelper._ID, SQLiteHelper.NAME, SQLiteHelper.AGE}, null, null, null, null, null); if (cursor != null) { cursor.moveToFirst(); } return cursor; } public int update(long _id, String name, String desc) { ContentValues contentValues = new ContentValues(); contentValues.put(SQLiteHelper.NAME, name); contentValues.put(SQLiteHelper.AGE, desc); return this.database.update(SQLiteHelper.TABLE_NAME_STUDENT, contentValues, "_id = " + _id, null); } public void delete(long _id) { this.database.delete(SQLiteHelper.TABLE_NAME_STUDENT, "_id=" + _id, null); }}然后创建一个
SQLiteOpenHelper我叫我的
SQLiteHelper.java
public class SQLiteHelper extends SQLiteOpenHelper { public static final String AGE = "age"; private static final String CREATE_TABLE_STUDENT = " create table STUDENTS ( _id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL , age TEXT );"; private static final String DB_NAME = "STUDENTS.DB"; private static final int DB_VERSION = 1; public static final String NAME = "name"; public static final String TABLE_NAME_STUDENT = "STUDENTS"; public static final String _ID = "_id"; public SQLiteHelper(Context context) { super(context, DB_NAME, null, 1); } public void onCreate(SQLiteDatabase db) { db.execSQL(CREATE_TABLE_STUDENT); } public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL("DROP TABLE IF EXISTS STUDENTS"); onCreate(db); } }添加：
在此示例中，我取自文本，
EditText单击按钮时，我检查是否
EditText为空。如果它不为空并且该学生不存在，则将学生的姓名和年龄插入数据库中。我显示一个
Toast，让用户知道状态：
btnAdd.setonClickListener(new View.onClickListener() { @Override public void onClick(View view) { if (edtName.getText().toString().trim().length() == 0) { Toast.makeText(getApplicationContext(), "Please provide your students name", Toast.LENGTH_SHORT).show(); } else{ try { if (edtAge.getText().toString().trim().length() != 0) { String name = edtName.getText().toString().trim(); String age = edtAge.getText().toString().trim(); String query = "Select * From STUDENTS where name = '"+name+"'"; if(dbManager.fetch().getCount()>0){ Toast.makeText(getApplicationContext(), "Already Exist!", Toast.LENGTH_SHORT).show(); }else{ dbManager.insert(name, age); Toast.makeText(getApplicationContext(), "Added successfully!", Toast.LENGTH_SHORT).show(); } } else { Toast.makeText(getApplicationContext(), "please provide student age!", Toast.LENGTH_SHORT).show(); } } catch (Exception e) { e.printStackTrace(); } } } });更新：
在这里，我将接受“文本”
EditText并在单击按钮时更新学生。您也可以将以下内容放在中
try/catch，以确保更新成功。
btnupdate.setonClickListener(new View.onClickListener() { @Override public void onClick(View view) { String name = nameText.getText().toString(); String age = ageText.getText().toString(); dbManager.update(_id, name, age); Toast.makeText(getApplicationContext(), "Updated successfully!", Toast.LENGTH_SHORT).show(); }});删除：
dbManager.delete(_id);Toast.makeText(getApplicationContext(), "Deleted successfully!", Toast.LENGTH_SHORT).show();
要得到：
在这里，我得到了学生的名字，并将其显示在
TextView
DBManager dbManager = new DBManager(getActivity());dbManager.open();Cursor cursor = dbManager.fetch();cursor.moveToFirst();final TextView studentName = (TextView) getActivity().findViewById(R.id.nameOfStudent);studentName.settext(cursor.getString(0));
