Android数据库操作

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package com.xxx.app.common.util;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;public class DBHelper4SP extends SQLiteOpenHelper{private static final String DATABASE_NAME = "SharedPref.db";private static final int DATABASE_VERSION = 3;public static final String TABLE_NAME = "tb_sp";private static DBHelper4SP instance = null;public static synchronized DBHelper4SP getInstance(Context context){if (instance == null) {instance = new DBHelper4SP(context);}return instance;}private DBHelper4SP(Context context){super(context, DATABASE_NAME, null, DATABASE_VERSION);}private static String sql = "";static{sql = "CREATE TABLE " + TABLE_NAME + "("+ "id INTEGER PRIMARY KEY AUTOINCREMENT," + "key TEXT,"+ "value TEXT" + ")";}@Overridepublic void onCreate(SQLiteDatabase db){db.execSQL(sql);}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){if (oldVersion < newVersion) {db.execSQL("DROP TABLE if exists " + TABLE_NAME);db.execSQL(sql);}}}

package com.xxxx.app.common.util;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;public class DBTool4SP{private final static String TAG = DBTool4SP.class.getCanonicalName();private static SQLiteDatabase sdb;private DBTool4SP() {}private static DBTool4SP instance = new DBTool4SP();public static DBTool4SP getInstance(Context context) {sdb = DBHelper4SP.getInstance(context).getWritableDatabase();return instance;}public void insert(String key, String value){delete(key);try{ContentValues values = new ContentValues();values.put("key", key);values.put("value", value);sdb.insert(DBHelper4SP.TABLE_NAME, "id", values);Log4Debug.e(TAG, "insert (" + key + ", " + value + ")");}catch (Exception e){e.printStackTrace();}}public void delete(String key){try{sdb.delete(DBHelper4SP.TABLE_NAME, "key = ?", new String[] { key });}catch (Exception e){e.printStackTrace();}}public String query(String key){String value = "";try{Cursor c = sdb.query(DBHelper4SP.TABLE_NAME, null, "key = ?",new String[] { key }, null, null, null);while (c.moveToNext())value = c.getString(2);}catch (Exception e){e.printStackTrace();}Log4Debug.e(TAG, "query (" + key + ", " + value + ")");return value;}}

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