Xamarin.Android 入门实例（4）之实现对 SQLLite 进行添加/修改/删除/查询操作

  1 using System;
  2 using System.Collections.Generic;
  3 using Android.App;
  4 using Android.Content;
  5 using Android.Runtime;
  6 using Android.Views;
  7 using Android.Widget;
  8 using Android.OS;
  9 
 10 namespace MyDatabaseDemo
 11 {
 12     /// <summary>
 13     /// Main Activity1 to start applicaton.
 14     /// </summary>
 15     [Activity (Label = "My Database Demo", MainLauncher = true)]
 16     public class Activity1 : Activity
 17     {
 18         /// <summary>
 19         /// The mdtemp is object of MyDatabase class.
 20         /// </summary>
 21         MyDatabase mdTemp;
 22         /// <summary>
 23         /// The txtName, txtAge, txtCountry are object of EditText.
 24         /// </summary>
 25         EditText txtName, txtAge, txtCountry;
 26         /// <summary>
 27         /// The tvMsg is object of TextView.
 28         /// </summary>
 29         TextView tvMsg;
 30         /// <summary>
 31         /// The imgAdd, imgEdit, imgDelete, imgFind are object of ImageButton
 32         /// </summary>
 33         ImageButton imgAdd, imgEdit, imgDelete, imgFind;
 34         /// <summary>
 35         /// Raises the create event for application.
 36         /// </summary>
 37         /// <param name=‘bundle‘>
 38         /// Bundle.
 39         /// </param>
 40         protected override void OnCreate (Bundle bundle)
 41         {
 42             base.OnCreate (bundle);
 43 
 44             // Set our view from the "main" layout resource
 45             SetContentView (Resource.Layout.Main);
 46 
 47             // Get our button from the layout resource,
 48             // and attach an event to it
 49 
 50             // initialization of database class object.
 51             mdTemp = new MyDatabase ("person_db");
 52             // get ImageButton object instance from resource.
 53             imgAdd = FindViewById<ImageButton> (Resource.Id.imgAdd);
 54             imgEdit = FindViewById<ImageButton> (Resource.Id.imgEdit);
 55             imgDelete = FindViewById<ImageButton> (Resource.Id.imgDelete);
 56             imgFind = FindViewById<ImageButton> (Resource.Id.imgFind);
 57             // set images on image button from resource.
 58             imgAdd.SetImageResource (Resource.Drawable.add);
 59             imgEdit.SetImageResource (Resource.Drawable.save);
 60             imgDelete.SetImageResource (Resource.Drawable.delete);
 61             imgFind.SetImageResource (Resource.Drawable.find);
 62             // get EditText object instance from resource.
 63             txtName = FindViewById<EditText> (Resource.Id.txtName);
 64             txtAge = FindViewById<EditText> (Resource.Id.txtAge);
 65             txtCountry = FindViewById<EditText> (Resource.Id.txtCountry);
 66             tvMsg = FindViewById<TextView> (Resource.Id.tvMsg);
 67 
 68             tvMsg.Text = mdTemp.Message;
 69 
 70             // 添加 ImageButton click event for imgAdd, imgEdit, imgDelete, imgFind. 
 71             imgAdd.Click += delegate {
 72                 //database call add record function AddRecord().
 73                 mdTemp.AddRecord (txtName.Text, int.Parse (txtAge.Text), txtCountry.Text);
 74                 tvMsg.Text = mdTemp.Message;
 75                 txtName.Text = txtAge.Text = txtCountry.Text = "";
 76             };
 77             //编辑
 78             imgEdit.Click += delegate {
 79                 int iId = -1;
 80                 int.TryParse (tvMsg.Text, out iId);
 81                 //database call update record function UpdateRecord().
 82                 mdTemp.UpdateRecord (iId, txtName.Text, int.Parse (txtAge.Text), txtCountry.Text);
 83                 tvMsg.Text = mdTemp.Message;
 84                 txtName.Text = txtAge.Text = txtCountry.Text = "";
 85             };
 86             //删除
 87             imgDelete.Click += delegate {
 88                 int iId = -1;
 89                 int.TryParse (tvMsg.Text, out iId);
 90                 //database call delete record function DeleteRecord().
 91                 mdTemp.DeleteRecord (iId);
 92                 tvMsg.Text = mdTemp.Message;
 93                 txtName.Text = txtAge.Text = txtCountry.Text = "";
 94             };
 95             //查找
 96             imgFind.Click += delegate {
 97 
 98                 //database call search record function GetCursorView().
 99                 string sColumnName = "";
100                 if (txtName.Text.Trim () != "") {
101                     sColumnName = "by Name";
102                     GetCursorView (sColumnName, txtName.Text.Trim ());
103                 } else
104                 if (txtAge.Text.Trim () != "") {
105                     sColumnName = "by Age";
106                     GetCursorView (sColumnName, txtAge.Text.Trim ());
107                 } else
108                 if (txtCountry.Text.Trim () != "") {
109                     sColumnName = "by Country";
110                     GetCursorView (sColumnName, txtCountry.Text.Trim ());
111                 } else {
112                     GetCursorView ();
113                     sColumnName = "All";
114                 }
115                 tvMsg.Text = "Search " + sColumnName + ".";
116             };
117 
118             // get ListView object instance from resource and add ItemClick, EventHandler.
119             ListView lvTemp = FindViewById<ListView> (Resource.Id.lvTemp);        
120             lvTemp.ItemClick += new EventHandler<AdapterView.ItemClickEventArgs> (ListView_ItemClick);
121 
122 
123         }
124         /// <summary>
125         /// Lists the view_ item click.
126         /// </summary>
127         /// <param name=‘sender‘>
128         /// object sender.
129         /// </param>
130         /// <param name=‘e‘>
131         /// ItemClickEventArgs e.
132         /// </param>
133         void ListView_ItemClick (object sender, AdapterView.ItemClickEventArgs e)
134         {
135             // get TextView object instance from resource layout record_view.axml.
136             TextView tvIdShow = e.View.FindViewById<TextView> (Resource.Id.tvIdShow);
137             TextView tvPersonShow = e.View.FindViewById<TextView> (Resource.Id.tvPersonShow);
138             TextView tvAgeShow = e.View.FindViewById<TextView> (Resource.Id.tvAgeShow);
139             TextView tvCountryShow = e.View.FindViewById<TextView> (Resource.Id.tvCountryShow);
140             // read value and wirte in EditText object.
141             txtName.Text = tvPersonShow.Text;
142             txtAge.Text = tvAgeShow.Text;
143             txtCountry.Text = tvCountryShow.Text;
144             //record id is write in TextView object to update or delete record.
145             tvMsg.Text = tvIdShow.Text;
146         }
147         /// <summary>
148         /// Gets the cursor view to show all record.
149         /// </summary>
150         protected void GetCursorView ()
151         {
152             Android.Database.ICursor icTemp = mdTemp.GetRecordCursor ();
153             if (icTemp != null) {
154                 icTemp.MoveToFirst ();
155                 ListView lvTemp = FindViewById<ListView> (Resource.Id.lvTemp);
156                 string[] from = new string[] {"_id","Name","Age","Country" };
157                 int[] to = new int[] {
158                     Resource.Id.tvIdShow,
159                     Resource.Id.tvPersonShow,
160                     Resource.Id.tvAgeShow,
161                     Resource.Id.tvCountryShow
162                 };
163                 // creating a SimpleCursorAdapter to fill ListView object.
164                 SimpleCursorAdapter scaTemp = new SimpleCursorAdapter (this, Resource.Layout.record_view, icTemp, from, to);
165                 lvTemp.Adapter = scaTemp;
166             } else {
167                 tvMsg.Text = mdTemp.Message;
168             }
169         }
170         /// <summary>
171         /// Gets the cursor view.
172         /// </summary>
173         /// <param name=‘sColumn‘>
174         /// column filed of MyTable is Name,Age,Country.
175         /// </param>
176         /// <param name=‘sValue‘>
177         /// Value as user input.
178         /// </param>
179         protected void GetCursorView (string sColumn, string sValue)
180         {
181             Android.Database.ICursor icTemp = mdTemp.GetRecordCursor (sColumn, sValue);
182             if (icTemp != null) {
183                 icTemp.MoveToFirst ();
184                 ListView lvTemp = FindViewById<ListView> (Resource.Id.lvTemp);
185                 string[] from = new string[] {"_id","Name","Age","Country" };
186                 int[] to = new int[] {
187                     Resource.Id.tvIdShow,
188                     Resource.Id.tvPersonShow,
189                     Resource.Id.tvAgeShow,
190                     Resource.Id.tvCountryShow
191                 };
192                 // creating a SimpleCursorAdapter to fill ListView object.
193                 SimpleCursorAdapter scaTemp = new SimpleCursorAdapter (this, Resource.Layout.record_view, icTemp, from, to);
194                 lvTemp.Adapter = scaTemp;
195             } else {
196                 tvMsg.Text = mdTemp.Message;
197             }
198         }
199     }
200 }

  1 using System;
  2 using System.Collections.Generic;
  3 using System.Linq;
  4 using System.Text;
  5 
  6 using Android.App;
  7 using Android.Content;
  8 using Android.OS;
  9 using Android.Runtime;
 10 using Android.Views;
 11 using Android.Widget;
 12 using Android.Database.Sqlite;
 13 using System.IO;
 14 
 15 namespace MyDatabaseDemo
 16 {
 17     public class MyDatabase
 18     {
 19         /// <summary>
 20         /// SQLiteDatabase object sqldTemp to handle SQLiteDatabase.
 21         /// </summary>
 22         private SQLiteDatabase sqldTemp;
 23         /// <summary>
 24         /// The sSQLquery for query handling.
 25         /// </summary>
 26         private string sSQLQuery;
 27         /// <summary>
 28         /// The sMessage to hold message.
 29         /// </summary>
 30         private string sMessage;
 31         /// <summary>
 32         /// The bDBIsAvailable for database is available or not.
 33         /// </summary>
 34         private bool bDBIsAvailable;
 35         /// <summary>
 36         /// Initializes a new instance of the <see cref="MyDatabaseDemo.MyDatabase"/> class.
 37         /// </summary>
 38         public MyDatabase ()
 39         {
 40             sMessage = "";
 41             bDBIsAvailable = false;
 42         }
 43         /// <summary>
 44         /// Initializes a new instance of the <see cref="MyDatabaseDemo.MyDatabase"/> class.
 45         /// </summary>
 46         /// <param name=‘sDatabaseName‘>
 47         /// Pass your database name.
 48         /// </param>
 49         public MyDatabase (string sDatabaseName)
 50         {
 51             try {
 52                 sMessage = "";
 53                 bDBIsAvailable = false;
 54                 CreateDatabase (sDatabaseName);
 55             } catch (SQLiteException ex) {
 56                 sMessage = ex.Message;
 57             }
 58         }
 59         /// <summary>
 60         /// Gets or sets a value indicating whether this <see cref="MyDatabaseDemo.MyDatabase"/> database available.
 61         /// </summary>
 62         /// <value>
 63         /// <c>true</c> if database available; otherwise, <c>false</c>.
 64         /// </value>
 65         public bool DatabaseAvailable {
 66             get{ return bDBIsAvailable;}
 67             set{ bDBIsAvailable = value;}
 68         }
 69         /// <summary>
 70         /// 消息
 71         /// </summary>
 72         /// <value>
 73         /// The message.
 74         /// </value>
 75         public string Message {
 76             get{ return sMessage;}
 77             set{ sMessage = value;}
 78         }
 79         /// <summary>
 80         /// 创建数据库
 81         /// </summary>
 82         /// <param name=‘sDatabaseName‘>
 83         /// Pass database name.
 84         /// </param>
 85         public void CreateDatabase (string sDatabaseName)
 86         {
 87             try {
 88                 sMessage = "";
 89                 string sLocation = System.Environment.GetFolderPath (System.Environment.SpecialFolder.Personal);
 90                 string sDB = Path.Combine (sLocation, sDatabaseName);
 91                 bool bIsExists = File.Exists (sDB);        
 92                 if (!bIsExists) {
 93                     sqldTemp = SQLiteDatabase.OpenOrCreateDatabase (sDB, null);
 94                     sSQLQuery = "CREATE TABLE IF NOT EXISTS " +
 95                         "MyTable " +
 96                         "(_id INTEGER PRIMARY KEY AUTOINCREMENT,Name VARCHAR,Age INT,Country VARCHAR);";
 97                     sqldTemp.ExecSQL (sSQLQuery);
 98                     sMessage = "New database is created.";
 99                 } else {
100                     sqldTemp = SQLiteDatabase.OpenDatabase (sDB, null, DatabaseOpenFlags.OpenReadwrite);
101                     sMessage = "Database is opened.";
102                 }
103                 bDBIsAvailable = true;
104             } catch (SQLiteException ex) {
105                 sMessage = ex.Message;
106             }
107         }
108         /// <summary>
109         /// 添加记录
110         /// </summary>
111         /// <param name=‘sName‘>
112         /// Pass name.
113         /// </param>
114         /// <param name=‘iAge‘>
115         /// Pass age.
116         /// </param>
117         /// <param name=‘sCountry‘>
118         /// Pass country.
119         /// </param>
120         public void AddRecord (string sName, int iAge, string sCountry)
121         {
122             try {
123                 sSQLQuery = "INSERT INTO " +
124                     "MyTable " +
125                     "(Name,Age,Country)" +
126                     "VALUES(‘" + sName + "‘," + iAge + ",‘" + sCountry + "‘);";
127                 sqldTemp.ExecSQL (sSQLQuery);
128                 sMessage = "Record is saved.";
129             } catch (SQLiteException ex) {
130                 sMessage = ex.Message;
131             }
132         }
133         /// <summary>
134         /// 更新记录
135         /// </summary>
136         /// <param name=‘iId‘>
137         /// Pass record ID.
138         /// </param>
139         /// <param name=‘sName‘>
140         /// Pass name.
141         /// </param>
142         /// <param name=‘iAge‘>
143         /// Pass age.
144         /// </param>
145         /// <param name=‘sCountry‘>
146         /// Pass country.
147         /// </param>
148         public void UpdateRecord (int iId, string sName, int iAge, string sCountry)
149         {
150             try {
151                 sSQLQuery = "UPDATE MyTable " +
152                     "SET Name=‘" + sName + "‘,Age=‘" + iAge + "‘,Country=‘" + sCountry + "‘ " +
153                     "WHERE _id=‘" + iId + "‘;";
154                 sqldTemp.ExecSQL (sSQLQuery);
155                 sMessage = "Record is updated: " + iId;
156             } catch (SQLiteException ex) {
157                 sMessage = ex.Message;
158             }
159         }
160         /// <summary>
161         /// 删除记录
162         /// </summary>
163         /// <param name=‘iId‘>
164         /// Pass ID.
165         /// </param>
166         public void DeleteRecord (int iId)
167         {
168             try {
169                 sSQLQuery = "DELETE FROM MyTable " +
170                     "WHERE _id=‘" + iId + "‘;";
171                 sqldTemp.ExecSQL (sSQLQuery);
172                 sMessage = "Record is deleted: " + iId;
173             } catch (SQLiteException ex) {
174                 sMessage = ex.Message;
175             }
176         }
177         /// <summary>
178         /// 获取当前记录游标
179         /// </summary>
180         /// <returns>
181         /// The record cursor.
182         /// </returns>
183         public Android.Database.ICursor GetRecordCursor ()
184         {
185             Android.Database.ICursor icTemp = null;
186             try {
187                 sSQLQuery = "SELECT * FROM MyTable;";
188                 icTemp = sqldTemp.RawQuery (sSQLQuery, null);
189                 if (!(icTemp != null)) {
190                     sMessage = "Record not found.";
191                 }
192             } catch (SQLiteException ex) {
193                 sMessage = ex.Message;
194             }
195             return icTemp;
196         }
197         /// <summary>
198         /// 获取符合检索条件的记录游标
199         /// </summary>
200         /// <returns>
201         /// The record cursor.
202         /// </returns>
203         /// <param name=‘sColumn‘>
204         /// column filed of MyTable is Name,Age,Country.
205         /// </param>
206         /// <param name=‘sValue‘>
207         /// Value as user input.
208         /// </param>
209         public Android.Database.ICursor GetRecordCursor (string sColumn, string sValue)
210         {
211             Android.Database.ICursor icTemp = null;
212             try {
213                 sSQLQuery = "SELECT * FROM MyTable WHERE " + sColumn + " LIKE ‘" + sValue + "%‘;";
214                 icTemp = sqldTemp.RawQuery (sSQLQuery, null);
215                 if (!(icTemp != null)) {
216                     sMessage = "Record not found.";
217                 }
218             } catch (SQLiteException ex) {
219                 sMessage = ex.Message;
220             }
221             return icTemp;
222         }
223         /// <summary>
224         /// 释放非托管资源并执行其他清理操作之前被垃圾回收
225         /// <see cref="MyDatabaseDemo.MyDatabase"/> 
226         /// </summary>
227         ~MyDatabase ()
228         {
229             try {
230                 sMessage = "";
231                 bDBIsAvailable = false;        
232                 sqldTemp.Close ();        
233             } catch (SQLiteException ex) {
234                 sMessage = ex.Message;
235             }
236         }
237     }
238 }