简单的增删改查

数据库代码

public class DBHelper {public static final String DB_NAME = "opinion_db";public static final String TABLE_NANE = "opinion_table";public static final int VERSION = 3;public static SQLiteDatabase db;// 只创建一次private OpenHelper openHelper;private final Context context;public DBHelper(Context context) {this.context = context;}public void openDB() {if (db == null) {openHelper = new OpenHelper(context, DB_NAME, null, VERSION);db = openHelper.getWritableDatabase();System.out.println("create database!");}}// 插入public long insert(OpinionModal opinion) {return db.insert(TABLE_NANE, null, putVaule(opinion));}// 查询@SuppressWarnings("unchecked")public ArrayList getAll() {ArrayList list = new ArrayList();Cursor cursor = null;cursor = db.query(TABLE_NANE, new String[] { "_id", "opinion"},null, null, null, null, null);while (cursor.moveToNext()) {list.add(mapPut(cursor));}return list;}// 根据_id删除单个或多个public void delete(int _id) {db.delete(TABLE_NANE, "_id=?", new String[] { String.valueOf(_id) });}// 删除所有public void deleteAll() {db.delete(TABLE_NANE, null, null);}// 删除标记的数据public void deleteMarked(ArrayList<Integer> deleteId) {StringBuffer stringBuffer = new StringBuffer();stringBuffer.append("_id=");for (int i = 0; i < deleteId.size(); i++) {if (i != deleteId.size() - 1) {stringBuffer.append(deleteId.get(i) + " or _id=");} else {stringBuffer.append(deleteId.get(i));}}db.delete(TABLE_NANE, stringBuffer.toString(), null);}// 封装了Map的put方法private Map<String, Object> mapPut(Cursor cursor) {// TODO Auto-generated method stubHashMap<String, Object> map = new HashMap<String, Object>();map.put("_id", cursor.getString(cursor.getColumnIndex("_id")));map.put("opinion", cursor.getString(cursor.getColumnIndex("opinion")));return map;}// 封装ContentValues的put方法public ContentValues putVaule(OpinionModal opinion) {ContentValues values = new ContentValues();values.put("opinion", opinion.opinion);return values;}class OpenHelper extends SQLiteOpenHelper {public OpenHelper(Context context, String name, CursorFactory factory,int version) {super(context, name, factory, version);}@Overridepublic void onCreate(SQLiteDatabase db) {String sql = "create table "+ TABLE_NANE+ "("+ "_id integer primary key autoincrement,opinion text"+ ")";db.execSQL(sql);}public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {String sql = "drop table if exists" + DB_NAME;db.execSQL(sql);openHelper.onCreate(db);}}}

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