Android利用Intent实现记事本功能（NotePad）

概述本文实例为大家分享了Intent如何实现一个简单的记事本功能的演示过程，供大家参考，具体内容如下

本文实例为大家分享了Intent如何实现一个简单的记事本功能的演示过程，供大家参考，具体内容如下

1、运行截图

单击右上角【…】会d出【添加】菜单项，长按某条记录会d出快捷菜单【删除】项。

2、主要设计步骤

（1）添加引用

鼠标右击【引用】à【添加引用】，在d出的窗口中勾选“System.Data”和“System.Data.sqlite”，如下图所示：

注意：不需要通过NuGet添加sqlite程序包，只需要按这种方式添加即可。

（2）添加图片

到AndroID SDK API 23的Samples的NotePad例子下找到app_notes.png，将其添加到该项目中，并将其换名为ch12_app_notes.png。

（3）添加ch1205_NoteEditor.axml文件

<?xml version="1.0" enCoding="utf-8"?><vIEw xmlns:androID="http://schemas.androID.com/apk/res/androID"    androID:ID="@+ID/note"  androID:layout_wIDth="match_parent"  androID:layout_height="match_parent"  androID:padding="5dip"  androID:scrollbars="vertical"  androID:fadingEdge="vertical"  androID:gravity="top"  androID:textSize="22sp"  androID:cAPItalize="sentences" />

（4）添加ch1205_Main.axml文件

<?xml version="1.0" enCoding="utf-8"?><linearLayout xmlns:androID="http://schemas.androID.com/apk/res/androID"  androID:layout_wIDth="fill_parent"  androID:layout_height="wrap_content"  androID:orIEntation="horizontal"  androID:background="#ffffff"  androID:padding="10px"> <ImageVIEw   androID:ID="@+ID/icon"   androID:layout_wIDth="wrap_content"   androID:layout_height="wrap_content"   androID:src="@drawable/ch12_app_notes" /> <linearLayout   androID:layout_wIDth="fill_parent"   androID:layout_height="wrap_content"   androID:orIEntation="vertical"   androID:paddingtop="6px">  <TextVIEw    androID:ID="@+ID/body"    androID:layout_wIDth="wrap_content"    androID:layout_height="wrap_content" />  <TextVIEw    androID:ID="@+ID/modifIEd"    androID:layout_wIDth="wrap_content"    androID:layout_height="wrap_content" /> </linearLayout></linearLayout> 

（5）添加ch1205Note.cs文件

using System;namespace MyDemos.SrcDemos{  class ch1205Note : java.lang.Object  {    public long ID { get; set; }    public string Body { get; set; }    public DateTime ModifIEdTime { get; set; }    public ch1205Note()    {      ID = -1L;      Body = string.Empty;    }    public ch1205Note(long ID,string body,DateTime modifIEd)    {      ID = ID;      Body = body;      ModifIEdTime = modifIEd;    }    public overrIDe string ToString()    {      return ModifIEdTime.ToString();    }  }} 

（6）添加ch1205linedEditText.cs文件

using AndroID.Content;using AndroID.Runtime;using AndroID.Widget;using AndroID.Graphics;using AndroID.Util;namespace MyDemos.SrcDemos{  [Register("MyDemos.SrcDemos.ch1205linedEditText")]  class ch1205linedEditText : EditText  {    private Rect rect;    private Paint paint;    // 为了LayoutInflater需要提供此构造函数    public ch1205linedEditText(Context context,IAttributeSet attrs)      : base(context,attrs)    {      rect = new Rect();      paint = new Paint();      paint.SetStyle(AndroID.Graphics.Paint.Style.@R_404_5283@);      paint.color = color.lightGray;    }    protected overrIDe voID OnDraw(Canvas canvas)    {      int count = lineCount;      for (int i = 0; i < count; i++)      {        int baseline = GetlineBounds(i,rect);        canvas.Drawline(rect.left,baseline + 1,rect.Right,paint);      }      base.OnDraw(canvas);    }  }}

（7）添加ch1205NoteRepository.cs文件

using System;using System.Collections.Generic;using Mono.Data.sqlite;namespace MyDemos.SrcDemos{  class ch1205NoteRepository  {    private static string db_file = "notes.db3";    private static sqliteConnection GetConnection()    {      var dbPath = System.IO.Path.Combine(        System.Environment.GetFolderPath(          System.Environment.SpecialFolder.Personal),db_file);      bool exists = System.IO.file.Exists(dbPath);      if (!exists) sqliteConnection.Createfile(dbPath);      var conn = new sqliteConnection("Data Source=" + dbPath);      if (!exists) CreateDatabase(conn);      return conn;    }    private static voID CreateDatabase(sqliteConnection connection)    {      var sql = "CREATE table ITEMS (ID INTEGER PRIMARY KEY autoINCREMENT,Body ntext,ModifIEd datetime);";      connection.open();      using (var cmd = connection.CreateCommand())      {        cmd.CommandText = sql;        cmd.ExecuteNonquery();      }      // Create a sample note to get the user started      sql = "INSERT INTO ITEMS (Body,ModifIEd) VALUES (@Body,@ModifIEd);";      using (var cmd = connection.CreateCommand())      {        cmd.CommandText = sql;        cmd.Parameters.AdDWithValue("@Body","今天有个约会");        cmd.Parameters.AdDWithValue("@ModifIEd",DateTime.Now);        cmd.ExecuteNonquery();      }      connection.Close();    }    public static IEnumerable<ch1205Note> GetAllNotes()    {      var sql = "SELECT * FROM ITEMS;";      using (var conn = GetConnection())      {        conn.open();        using (var cmd = conn.CreateCommand())        {          cmd.CommandText = sql;          using (var reader = cmd.ExecuteReader())          {            while (reader.Read())            {              yIEld return new ch1205Note(                reader.GetInt32(0),reader.GetString(1),reader.GetDateTime(2));            }          }        }      }    }    public static ch1205Note GetNote(long ID)    {      var sql = "SELECT * FROM ITEMS WHERE ID = ID;";      using (var conn = GetConnection())      {        conn.open();        using (var cmd = conn.CreateCommand())        {          cmd.CommandText = sql;          using (var reader = cmd.ExecuteReader())          {            if (reader.Read())              return new ch1205Note(reader.GetInt32(0),reader.GetDateTime(2));            else              return null;          }        }      }    }    public static voID DeleteNote(ch1205Note note)    {      var sql = string.Format("DELETE FROM ITEMS WHERE ID = {0};",note.ID);      using (var conn = GetConnection())      {        conn.open();        using (var cmd = conn.CreateCommand())        {          cmd.CommandText = sql;          cmd.ExecuteNonquery();        }      }    }    public static voID SaveNote(ch1205Note note)    {      using (var conn = GetConnection())      {        conn.open();        using (var cmd = conn.CreateCommand())        {          if (note.ID < 0)          {            // Do an insert            cmd.CommandText = "INSERT INTO ITEMS (Body,@ModifIEd); SELECT last_insert_rowID();";            cmd.Parameters.AdDWithValue("@Body",note.Body);            cmd.Parameters.AdDWithValue("@ModifIEd",DateTime.Now);            note.ID = (long)cmd.ExecuteScalar();          }          else          {            // Do an update            cmd.CommandText = "UPDATE ITEMS SET Body = @Body,ModifIEd = @ModifIEd WHERE ID = @ID";            cmd.Parameters.AdDWithValue("@ID",note.ID);            cmd.Parameters.AdDWithValue("@Body",DateTime.Now);            cmd.ExecuteNonquery();          }        }      }    }  }} 

（8）添加ch1205NoteAdapter.cs文件

using AndroID.App;using AndroID.Content;using AndroID.Widget;namespace MyDemos.SrcDemos{  class ch1205NoteAdapter : ArrayAdapter  {    private Activity activity;    public ch1205NoteAdapter(Activity activity,Context context,int textVIEwResourceID,ch1205Note[] objects)      : base(context,textVIEwResourceID,objects)    {      this.activity = activity;    }    public overrIDe AndroID.VIEws.VIEw GetVIEw(int position,AndroID.VIEws.VIEw convertVIEw,AndroID.VIEws.VIEwGroup parent)    {      //Get our object for this position      var item = (ch1205Note)GetItem(position);      // 如果convertVIEw不为null则重用它，否则从当前布局中填充（inflate）它。      // 由于这种方式不是每次都填充一个新的vIEw，因此可提高性能。      var vIEw = (convertVIEw ?? activity.LayoutInflater.Inflate(        Resource.Layout.ch1205_Main,parent,false)) as linearLayout;      vIEw.FindVIEwByID<TextVIEw>(Resource.ID.body).Text = left(item.Body.Replace("\n"," "),25);      vIEw.FindVIEwByID<TextVIEw>(Resource.ID.modifIEd).Text = item.ModifIEdTime.ToString();      return vIEw;    }    private string left(string text,int length)    {      if (text.Length <= length) return text;      return text.Substring(0,length);    }  }} 

（9）添加ch1205NoteEditorActivity.cs文件

using AndroID.App;using AndroID.Content;using AndroID.OS;using AndroID.Widget;using AndroID.Content.PM;namespace MyDemos.SrcDemos{  [Activity(Label = "ch1205NoteEditorActivity",ScreenorIEntation = ScreenorIEntation.Sensor,ConfigurationChanges = ConfigChanges.KeyboardHIDden | ConfigChanges.OrIEntation)]  public class ch1205NoteEditorActivity : Activity  {    private ch1205Note note;    private EditText text_vIEw;    protected overrIDe voID OnCreate(Bundle savedInstanceState)    {      base.OnCreate(savedInstanceState);      SetContentVIEw(Resource.Layout.ch1205_NoteEditor);      text_vIEw = FindVIEwByID<EditText>(Resource.ID.note);      var note_ID = Intent.GetLongExtra("note_ID",-1L);      if (note_ID < 0) note = new ch1205Note();      else note = ch1205NoteRepository.GetNote(note_ID);    }    protected overrIDe voID OnResume()    {      base.OnResume();      text_vIEw.SetTextKeepState(note.Body);    }    protected overrIDe voID OnPause()    {      base.OnPause();      // 如果是新建的记事本且没有内容，不保存直接返回。      if (IsFinishing && note.ID == -1 && text_vIEw.Text.Length == 0)        return;      // 保存记事本      note.Body = text_vIEw.Text;      ch1205NoteRepository.SaveNote(note);    }  }}

（10）添加ch1205NotePadMain.cs文件

using System.linq;using AndroID.App;using AndroID.Content;using AndroID.OS;using AndroID.VIEws;using AndroID.Widget;namespace MyDemos.SrcDemos{  [Activity(Label = "ch1205NotePadMain")]  public class ch1205NotePadMain : ListActivity  {    // 菜单项    public const int MenuItemDelete = Menu.First;    public const int MenuItemInsert = Menu.First + 1;    protected overrIDe voID OnCreate(Bundle savedInstanceState)    {      base.OnCreate(savedInstanceState);      SetDefaultKeyMode(DefaultKey.Shortcut);      ListVIEw.SetonCreateContextMenuListener(this);      PopulateList();    }    public voID PopulateList()    {      // 获取存放到列表中的所有记事本项      var notes = ch1205NoteRepository.GetAllNotes();      var adapter = new ch1205NoteAdapter(this,this,Resource.Layout.ch1205_Main,notes.ToArray());      listadapter = adapter;    }    public overrIDe bool OnCreateOptionsMenu(IMenu menu)    {      base.OnCreateOptionsMenu(menu);      menu.Add(0,MenuItemInsert,"添加")        .SetShortcut('3','a')        .SetIcon(AndroID.Resource.Drawable.IcmenuAdd);      return true;    }    public overrIDe bool OnoptionsItemSelected(IMenuItem item)    {      switch (item.ItemID)      {        case MenuItemInsert: // 通过intent添加新项          var intent = new Intent(this,typeof(ch1205NoteEditorActivity));          intent.PutExtra("note_ID",-1L);          StartActivityForResult(intent,0);          return true;      }      return base.OnoptionsItemSelected(item);    }    public overrIDe voID OnCreateContextMenu(IContextMenu menu,VIEw vIEw,IContextMenuContextMenuInfo menuInfo)    {      var info = (AdapterVIEw.AdapterContextMenuInfo)menuInfo;      var note = (ch1205Note)listadapter.GetItem(info.position);      menu.Add(0,MenuItemDelete,"删除");    }    public overrIDe bool OnContextItemSelected(IMenuItem item)    {      var info = (AdapterVIEw.AdapterContextMenuInfo)item.MenuInfo;      var note = (ch1205Note)listadapter.GetItem(info.position);      switch (item.ItemID)      {        case MenuItemDelete: // 删除该记事本项          ch1205NoteRepository.DeleteNote(note);          PopulateList();          return true;      }      return false;    }    protected overrIDe voID OnListItemClick(ListVIEw l,VIEw v,int position,long ID)    {      var selected = (ch1205Note)listadapter.GetItem(position);      // 执行activity，查看/编辑当前选中的项      var intent = new Intent(this,typeof(ch1205NoteEditorActivity));      intent.PutExtra("note_ID",selected.ID);      StartActivityForResult(intent,0);    }    protected overrIDe voID OnActivityResult(int requestCode,Result resultCode,Intent data)    {      base.OnActivityResult(requestCode,resultCode,data);      // 当列表项发生变化时，这里仅关心如何刷新它，并没有处理选定的项      PopulateList();    }  }}

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