JAVA 数据库操作工具类----sqllite
package com.asc.db; import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; /** * 数据库公共类,提供基本数据库操作*/ public class DBManager { // 默认数据库 private static final String DB_NAME = "asc.db"; // 数据库版本 private static final int DB_VERSION = 1; // 执行open()打开数据库时,保存返回的数据库对象 private SQLiteDatabase mSQLiteDatabase = null; // 由SQLiteOpenHelper继承过来 private DatabaseHelper mDatabaseHelper = null; // 本地Context对象 private Context mContext = null; private static DBManager dbConn= null; // 查询游标对象 private Cursor cursor; /** * SQLiteOpenHelper内部类 */ private static class DatabaseHelper extends SQLiteOpenHelper { DatabaseHelper(Context context) { // 当调用getWritableDatabase()或 getReadableDatabase()方法时,创建一个数据库 super(context, DB_NAME, null, DB_VERSION); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL("CREATE TABLE ad_record(id PRIMARY KEY NOT NULL, adUrl TEXT, apMac TEXT, createDate DATETIME);"); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL("DROP TABLE IF EXISTS ad_record"); onCreate(db); } } /** * 构造函数 * * @param mContext */ private DBManager(Context mContext) { super(); this.mContext = mContext; } public static DBManager getInstance(Context mContext){ if (null == dbConn) { dbConn = new DBManager(mContext); } return dbConn; } /** * 打开数据库 */ public void open() { mDatabaseHelper = new DatabaseHelper(mContext); mSQLiteDatabase = mDatabaseHelper.getWritableDatabase(); } /** * 关闭数据库 */ public void close() { if (null != mDatabaseHelper) { mDatabaseHelper.close(); } if (null != cursor) { cursor.close(); } } /** * 插入数据 * @param tableName 表名 * @param nullColumn null * @param contentValues 名值对 * @return 新插入数据的ID,错误返回-1 * @throws Exception */ public long insert(String tableName, String nullColumn, ContentValues contentValues) throws Exception { try { return mSQLiteDatabase.insert(tableName, nullColumn, contentValues); } catch (Exception e) { throw e; } } /** * 通过主键ID删除数据 * @param tableName 表名 * @param key 主键名 * @param id 主键值 * @return 受影响的记录数 * @throws Exception */ public long delete(String tableName, String key, int id) throws Exception { try { return mSQLiteDatabase.delete(tableName, key + " = " + id, null); } catch (Exception e) { throw e; } } /** * 查找表的所有数据 * @param tableName 表名 * @param columns 如果返回所有列,则填null * @return * @throws Exception */ public Cursor findAll(String tableName, String [] columns) throws Exception{ try { cursor = mSQLiteDatabase.query(tableName, columns, null, null, null, null, null); cursor.moveToFirst(); return cursor; } catch (Exception e) { throw e; } } /** * 根据主键查找数据 * @param tableName 表名 * @param key 主键名 * @param id 主键值 * @param columns 如果返回所有列,则填null * @return Cursor游标 * @throws Exception */ public Cursor findById(String tableName, String key, int id, String [] columns) throws Exception { try { return mSQLiteDatabase.query(tableName, columns, key + " = " + id, null, null, null, null); } catch (Exception e) { throw e; } } /** * 根据条件查询数据 * @param tableName 表名 * @param names 查询条件 * @param values 查询条件值 * @param columns 如果返回所有列,则填null * @param orderColumn 排序的列 * @param limit 限制返回数 * @return Cursor游标 * @throws Exception */ public Cursor find(String tableName, String [] names, String [] values, String [] columns, String orderColumn, String limit) throws Exception{ try { StringBuffer selection = new StringBuffer(); for (int i = 0; i < names.length; i++) { selection.append(names[i]); selection.append(" = ?"); if (i != names.length - 1) { selection.append(","); } } cursor = mSQLiteDatabase.query(true, tableName, columns, selection.toString(), values, null, null, orderColumn, limit); cursor.moveToFirst(); return cursor; } catch (Exception e) { throw e; } } /** * * @param tableName 表名 * @param names 查询条件 * @param values 查询条件值 * @param args 更新列-值对 * @return true或false * @throws Exception */ public boolean udpate(String tableName, String [] names, String [] values, ContentValues args) throws Exception{ try { StringBuffer selection = new StringBuffer(); for (int i = 0; i < names.length; i++) { selection.append(names[i]); selection.append(" = ?"); if (i != names.length - 1) { selection.append(","); } } return mSQLiteDatabase.update(tableName, args, selection.toString(), values) > 0; } catch (Exception e) { throw e; } } /** * 执行sql语句,包括创建表、删除、插入 * * @param sql */ public void executeSql(String sql) { mSQLiteDatabase.execSQL(sql); } }