Android(安卓)in Mono开发初体验之DataBase
16lz
2021-01-24
本文给大家介绍在MonoDevelop环境下操作SQLite数据库的功能，使得在Android中方便的实现对数据的增、删、改、查功能。
数据存储在开发中的重要性我就不再多说了，你懂的。关于Android中的数据存储技术有兴趣或需要的朋友可以查看我以前的一篇博文：http://www.cnblogs.com/hanyonglu/archive/2012/03/01/2374894.html
今天这个示例是给大家展示在MonoDevelop中操作Sqlite数据库的功能。关于Sqlite数据库大家仍然可以查看我以前的那篇文章，这里不再详述。如果有Android基础的朋友一看这篇文章就能明白，毕竟和用JAVA开发的原理都是一样的；如果没有Android基础的朋友，那么希望这篇文章能给你带来帮助，不过需要明白的是这篇文章是在MonoDevelop中开发的。
首先，我们需要先在MonoDevelop中新建一个解决方案。然后新建一个类命名为：DataBaseHelper。其代码如下所示：
using System;using Android.Database.Sqlite;using Android.App;using Android.Content;using Android.OS;using Android.Runtime;using Android.Views;using Android.Widget;using System.IO;namespace MyDataDemo{ /// <summary> /// Data base helper. /// Description:数据库操作类 /// Author:Hanyonglu /// Date:2012-08-26 15:30:56 /// </summary> public class DataBaseHelper { // Sqlite数据库对象 private SQLiteDatabase dataBase; private string strQuery; // 程序跟踪消息 private string message; private bool isAvailable; public DataBaseHelper () { } /// <summary> /// 构造器创建数据库 /// </summary> /// <param name='dataBaseName'> /// Data base name. /// </param> public DataBaseHelper (string dataBaseName) { try { CreateDatabase (dataBaseName); } catch (SQLiteException ex) { message = ex.Message; } } /// <summary> /// 获取或设置程序跟踪消息 /// </summary> /// <value> /// The message. /// </value> public string Message { get{ return message;} set{ message = value;} } /// <summary> /// 获取或设置数据库是否可用的状态 /// </summary> /// <value> /// <c>true</c> if this instance is available; otherwise, <c>false</c>. /// </value> public bool IsAvailable { get{ return isAvailable;} set{ isAvailable = value;} } /// <summary> /// 创建数据库 /// </summary> /// <param name='dataBaseName'> /// Data base name. /// </param> public void CreateDatabase (string dataBaseName) { try { message = ""; string location = System.Environment.GetFolderPath (System.Environment.SpecialFolder.Personal); string dataBasePath = Path.Combine (location, dataBaseName); bool isExistDataBase = File.Exists (dataBasePath); if (!isExistDataBase) { // 如果数据库不存在则直接创建数据库 dataBase = SQLiteDatabase.OpenOrCreateDatabase (dataBasePath, null); // 创建数据表 strQuery = "CREATE TABLE " + "IF NOT EXISTS MyContacts " + "(_id INTEGER PRIMARY KEY AUTOINCREMENT,Name VARCHAR,Tel INT,Address VARCHAR);"; dataBase.ExecSQL (strQuery); message = "创建数据库"; } else { // 如果数据库存在直接打开 dataBase = SQLiteDatabase.OpenDatabase (dataBasePath, null, DatabaseOpenFlags.OpenReadwrite); message = "打开数据库"; } isAvailable = true; } catch (SQLiteException ex) { message = ex.Message; } } /// <summary> /// 添加一个新联系人信息 /// </summary> /// <param name='name'> /// Name. /// </param> /// <param name='tel'> /// Tel. /// </param> /// <param name='address'> /// Address. /// </param> public void AddNewPerson (string name, int tel, string address) { try { strQuery = "INSERT INTO MyContacts (Name,Tel,Address)" + "VALUES('" + name + "'," + tel + ",'" + address + "');"; dataBase.ExecSQL (strQuery); message = "增加了一个新联系人的信息"; } catch (SQLiteException ex) { message = ex.Message; } } /// <summary> /// 根据id更新一个联系人信息 /// </summary> /// <param name='id'> /// Identifier. /// </param> /// <param name='name'> /// Name. /// </param> /// <param name='tel'> /// Tel. /// </param> /// <param name='address'> /// Address. /// </param> public void UpdatePerson (int id, string name, int tel, string address) { try { strQuery = "UPDATE MyContacts SET Name='" + name + "',Tel='" + tel + "',Address='" + address + "' " + "WHERE _id='" + id + "';"; dataBase.ExecSQL (strQuery); message = "更新了一个联系人的信息"; } catch (SQLiteException ex) { message = ex.Message; } } /// <summary> /// 根据id删除一个联系人信息 /// </summary> /// <param name='id'> /// Identifier. /// </param> public void DeletePerson (int id) { try { strQuery = "DELETE FROM MyContacts WHERE _id='" + id + "';"; dataBase.ExecSQL (strQuery); message = "删除了一个联系人的信息"; } catch (SQLiteException ex) { message = ex.Message; } } /// <summary> /// 获取所有联系人信息 /// </summary> /// <returns> /// The all persons. /// </returns> public Android.Database.ICursor GetAllPersons () { Android.Database.ICursor cursor = null; try { strQuery = "SELECT * FROM MyContacts;"; cursor = dataBase.RawQuery (strQuery, null); if (cursor != null) { message = "获取所有联系人的信息"; } else { message = "未找到相应的联系人的信息"; } } catch (SQLiteException ex) { message = ex.Message; } return cursor; } /// <summary> /// 根据模糊查询获取联系人信息 /// </summary> /// <returns> /// The like person. /// </returns> /// <param name='content'> /// Content. /// </param> /// <param name='value'> /// Value. /// </param> public Android.Database.ICursor GetLikePersons (string content, string value) { Android.Database.ICursor cursor = null; try { strQuery = "SELECT * FROM MyContacts WHERE " + content + " LIKE '%" + value + "%';"; cursor = dataBase.RawQuery (strQuery, null); if (cursor != null) { message = "获取模糊查询的联系人的信息"; } else { message = "未找到相应的联系人的信息"; } } catch (SQLiteException ex) { message = ex.Message; } return cursor; } /// <summary> /// 释放资源 /// <see cref="MyDataDemo.DataBaseHelper"/> is reclaimed by garbage collection. /// </summary> ~DataBaseHelper() { try { message = null; isAvailable = false; dataBase.Close (); } catch (SQLiteException ex) { message = ex.Message; } } }}
最后，希望转载的朋友能够尊重作者的劳动成果，加上转载地址：http://www.cnblogs.com/hanyonglu/archive/2012/08/26/2657648.html谢谢。
未完待续。^_^
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