Android数据库(SqlLite)操作

 

1.package com.xiaoshan.udp.client.db;
 2.
 3.import Android.content.ContentValues;
 4.import Android.content.Context;
 5.import Android.database.Cursor;
 6.import Android.database.SQLException;
 7.import Android.database.sqlite.SQLiteDatabase;
 8.import Android.database.sqlite.SQLiteOpenHelper;
 9.
 10./**
 11. * 数据库常用操作的封装类
 12. *
 13. *
 14. *
 15. */
 16.public class DBHelper {
 17.
 18.    private static DatabaseHelper mDbHelper;
 19.    private static SQLiteDatabase mDb;
 20.
 21.    private static final String DATABASE_NAME = "shanhy.db";
 22.
 23.    private static final int DATABASE_VERSION = 1;
 24.
 25.    private final Context mCtx;
 26.
 27.    private static class DatabaseHelper extends SQLiteOpenHelper {
 28.
 29.        DatabaseHelper(Context context) {
 30.            super(context, DATABASE_NAME, null, DATABASE_VERSION);
 31.        }
 32.
 33.        @Override
 34.        public void onCreate(SQLiteDatabase db) {
 35.        }
 36.
 37.        @Override
 38.        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
 39.        }
 40.    }
 41.
 42.    public DBHelper(Context ctx) {
 43.        this.mCtx = ctx;
 44.    }
 45.
 46.    public DBHelper open() throws SQLException {
 47.        mDbHelper = new DatabaseHelper(mCtx);
 48.        mDb = mDbHelper.getWritableDatabase();
 49.        return this;
 50.    }
 51.
 52.    /**
 53.     * 关闭数据源
 54.     *
 55.     * @author SHANHY
 56.     */
 57.    public void closeConnection() {
 58.        if (mDb != null && mDb.isOpen())
 59.            mDb.close();
 60.        if (mDbHelper != null)
 61.            mDbHelper.close();
 62.    }
 63.
 64.    /**
 65.     * 插入数据 参数
 66.     *
 67.     * @param tableName
 68.     *            表名
 69.     * @param initialValues
 70.     *            要插入的列对应值
 71.     * @return
 72.     * @author SHANHY
 73.     */
 74.    public long insert(String tableName, ContentValues initialValues) {
 75.
 76.        return mDb.insert(tableName, null, initialValues);
 77.    }
 78.
 79.    /**
 80.     * 删除数据
 81.     *
 82.     * @param tableName
 83.     *            表名
 84.     * @param deleteCondition
 85.     *            条件
 86.     * @param deleteArgs
 87.     *            条件对应的值（如果deleteCondition中有“？”号，将用此数组中的值替换，一一对应）
 88.     * @return
 89.     * @author SHANHY
 90.     */
 91.    public boolean delete(String tableName, String deleteCondition, String[] deleteArgs) {
 92.
 93.        return mDb.delete(tableName, deleteCondition, deleteArgs) > 0;
 94.    }
 95.
 96.    /**
 97.     * 更新数据
 98.     *
 99.     * @param tableName
 100.     *            表名
 101.     * @param initialValues
 102.     *            要更新的列
 103.     * @param selection
 104.     *            更新的条件
 105.     * @param selectArgs
 106.     *            更新条件中的“？”对应的值
 107.     * @return
 108.     * @author SHANHY
 109.     */
 110.    public boolean update(String tableName, ContentValues initialValues, String selection, String[] selectArgs) {
 111.        return mDb.update(tableName, initialValues, selection, selectArgs) > 0;
 112.    }
 113.
 114.    /**
 115.     * 取得一个列表
 116.     *
 117.     * @param distinct
 118.     *            是否去重复
 119.     * @param tableName
 120.     *            表名
 121.     * @param columns
 122.     *            要返回的列
 123.     * @param selection
 124.     *            条件
 125.     * @param selectionArgs
 126.     *            条件中“？”的参数值
 127.     * @param groupBy
 128.     *            分组
 129.     * @param having
 130.     *            分组过滤条件
 131.     * @param orderBy
 132.     *            排序
 133.     * @return
 134.     * @author SHANHY
 135.     */
 136.    public Cursor findList(boolean distinct, String tableName, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit) {
 137.
 138.        return mDb.query(distinct, tableName, columns, selection, selectionArgs, groupBy, having, orderBy, limit);
 139.    }
 140.
 141.    /**
 142.     * 取得单行记录
 143.     *
 144.     * @param tableName
 145.     *            表名
 146.     * @param columns
 147.     *            获取的列数组
 148.     * @param selection
 149.     *            条件
 150.     * @param selectionArgs
 151.     *            条件中“？”对应的值
 152.     * @param groupBy
 153.     *            分组
 154.     * @param having
 155.     *            分组条件
 156.     * @param orderBy
 157.     *            排序
 158.     * @param limit
 159.     *            数据区间
 160.     * @param distinct
 161.     *            是否去重复
 162.     * @return
 163.     * @throws SQLException
 164.     * @author SHANHY
 165.     */
 166.    public Cursor findOne(boolean distinct,String tableName, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit) throws SQLException {
 167.
 168.        Cursor mCursor = findList(distinct, tableName, columns, selection, selectionArgs, groupBy, having, orderBy, limit);
 169.
 170.        if (mCursor != null) {
 171.            mCursor.moveToFirst();
 172.        }
 173.        return mCursor;
 174.
 175.    }
 176.
 177.    /**
 178.     * 执行SQL(带参数)
 179.     *
 180.     * @param sql
 181.     * @param args
 182.     *            SQL中“？”参数值
 183.     * @author SHANHY
 184.     */
 185.    public void execSQL(String sql, Object[] args) {
 186.        mDb.execSQL(sql, args);
 187.
 188.    }
 189.
 190.    /**
 191.     * 执行SQL
 192.     *
 193.     * @param sql
 194.     * @author SHANHY
 195.     */
 196.    public void execSQL(String sql) {
 197.        mDb.execSQL(sql);
 198.
 199.    }
 200.
 201.    /**
 202.     * 判断某张表是否存在
 203.     *
 204.     * @param tabName
 205.     *            表名
 206.     * @return
 207.     */
 208.    public boolean isTableExist(String tableName) {
 209.        boolean result = false;
 210.        if (tableName == null) {
 211.            return false;
 212.        }
 213.
 214.        try {
 215.            Cursor cursor = null;
 216.            String sql = "select count(1) as c from sqlite_master where type ='table' and name ='" + tableName.trim() + "'";
 217.            cursor = mDb.rawQuery(sql, null);
 218.            if (cursor.moveToNext()) {
 219.                int count = cursor.getInt(0);
 220.                if (count > 0) {
 221.                    result = true;
 222.                }
 223.            }
 224.
 225.            cursor.close();
 226.        } catch (Exception e) {
 227.        }
 228.        return result;
 229.    }
 230.
 231.    /**
 232.     * 判断某张表中是否存在某字段(注，该方法无法判断表是否存在，因此应与isTableExist一起使用)
 233.     *
 234.     * @param tabName
 235.     *            表名
 236.     * @param columnName
 237.     *            列名
 238.     * @return
 239.     */
 240.    public boolean isColumnExist(String tableName, String columnName) {
 241.        boolean result = false;
 242.        if (tableName == null) {
 243.            return false;
 244.        }
 245.
 246.        try {
 247.            Cursor cursor = null;
 248.            String sql = "select count(1) as c from sqlite_master where type ='table' and name ='" + tableName.trim() + "' and sql like '%" + columnName.trim() + "%'";
 249.            cursor = mDb.rawQuery(sql, null);
 250.            if (cursor.moveToNext()) {
 251.                int count = cursor.getInt(0);
 252.                if (count > 0) {
 253.                    result = true;
 254.                }
 255.            }
 256.
 257.            cursor.close();
 258.        } catch (Exception e) {
 259.        }
 260.        return result;
 261.    }
 262.
 263.}