xamarin android alertdialog详解

说明一下：学习xamarin android一段时间，准备写一些xamarin android相关的例子，alertdialog也是使用的非常多得空间之一，非常感谢鸟巢上的小猪，我也是看着他写的教程学会的。参考他的那一章 http://www.runoob.com/w3cnote/android-tutorial-alertdialog.html

1.基本使用流程

• Step 1：创建AlertDialog.Builder对象；
• Step 2：调用setIcon()设置图标，setTitle()或setCustomTitle()设置标题；
• Step 3：设置对话框的内容：setMessage()还有其他方法来指定显示的内容；
• Step 4：调用setPositive/Negative/NeutralButton()设置：确定，取消，中立按钮；
• Step 5：调用create()方法创建这个对象，再调用show()方法将对话框显示出来；

2.几种常用的对话框使用示例

运行效果图：

主要代码：MainActivity.class

public class MainActivity : Activity
    {
        int count = 1;
        private Button btn_alertDialog_one, btn_alertDialog_two, btn_alertDialog_three, btn_alertDialog_four;

        private bool[] checkItems;
        private AlertDialog alertDialog = null;
        private AlertDialog.Builder builder = null;
        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);
            SetContentView(Resource.Layout.Main);
             bindViewClick();
        }

        private void bindViewClick()
        {
            btn_alertDialog_four = FindViewById<Button>(Resource.Id.btn_alertDialog_four);
            btn_alertDialog_three = FindViewById<Button>(Resource.Id.btn_alertDialog_three);
            btn_alertDialog_two = FindViewById<Button>(Resource.Id.btn_alertDialog_two);
            btn_alertDialog_one = FindViewById<Button>(Resource.Id.btn_alertDialog_one);

            btn_alertDialog_one.Click += delegate { onClick(btn_alertDialog_one); };
            btn_alertDialog_two.Click += delegate { onClick(btn_alertDialog_two); };
            btn_alertDialog_three.Click += delegate { onClick(btn_alertDialog_three); };
            btn_alertDialog_four.Click += delegate { onClick(btn_alertDialog_four); };
        }
        private void onClick(View v)
        {
            switch (v.Id)
            {
                case Resource.Id.btn_alertDialog_one:
                    alertDialog = null;
                    builder = new AlertDialog.Builder(this);
                    alertDialog = builder
                   .SetTitle("sure")
                   .SetMessage("are you sure exit?")
                   .SetNegativeButton("cancel", (s, e) =>
                    {
                        Toast.MakeText(this, "you click cancel", ToastLength.Short).Show();
                    })
                   .SetPositiveButton("sure", (s, e) =>
                   {
                       Toast.MakeText(this, "you click sure", ToastLength.Short).Show();
                   })
                   .SetNeutralButton("neutra", (s, e) => {
                       Toast.MakeText(this, "you click neutra", ToastLength.Short).Show();
                   })
                   .Create();       //创建alertDialog对象

                   alertDialog.Show();
                    var dialog = new AlertDialog.Builder(this);
                    break;

                case Resource.Id.btn_alertDialog_two:
                    alertDialog = null;
                    builder = new AlertDialog.Builder(this);
                    string[] players = new string[] {"杜兰特","汤普森","考辛斯","卡戴珊"};
                    alertDialog = builder
                        .SetIcon(Resource.Drawable.players)
                        .SetTitle("选择你喜欢的球员")
                         .SetItems(players, (s, e) =>
                         {
                             Toast.MakeText(this, "you selected " + players[e.Which], ToastLength.Short).Show();
                         })
                        .Create();
                    alertDialog.Show();
                    break;

                case Resource.Id.btn_alertDialog_three:
                    var a = new AlertDialog.Builder(this);
                    string[] teams = new string[] {"骑士","公牛","快船","马刺","勇士" };
                    a.SetTitle("你认为下个赛季哪只球队能夺冠")
                        .SetSingleChoiceItems(teams, 0, (s, e) =>
                        {
                            Toast.MakeText(this, "you selected " + teams[e.Which], ToastLength.Short).Show();
                        })
                        .Create();
                    a.Show();
                    break;

                 case Resource.Id.btn_alertDialog_four:
                    var b = new AlertDialog.Builder(this);
                    string[] menu = new string[] { "麻婆豆腐","羊蝎子","驴肉火烧","辣子鸡丁"};
                    checkItems = new bool[] {false,false,false,false};
                    b = b.SetIcon(Resource.Drawable.Icon)
                      .SetMultiChoiceItems(menu, checkItems, (s, e) => {
                            //Toast.MakeText(this, "you selected " + menu[e.Which], ToastLength.Short).Show();
                            checkItems[e.Which] = e.IsChecked;
                      })
                      .SetPositiveButton("确定", (s, e) => {
                          string result = string.Empty;
                          for (int i = 0; i < checkItems.Length; i++)
                          {
                              if (checkItems[i])
                              {
                                  result += menu[i] + ",";
                              }
                          }
                          Toast.MakeText(this, "you selected " + result, ToastLength.Short).Show();
                      });
                    b.Create();
                    b.Show();
                    break;
            }
        }
    }

用法非常简单创建一个Builder对象后，调用Create方法创建一个AlertDialog对象，最后调用show方法显示出来，当然你也可以像这样直接new 一个AlertDialog对象

 var b = new AlertDialog.Builder(this);

设置一个setCancelable (true|false)看看有没有什么区别

3.通过Builder的setView()定制显示的AlertDialog

我们可以自定义一个与系统对话框不同的布局，然后调用setView()将我们的布局加载到AlertDialog上，上面我们来实现这个效果：

我就贴一下几个主要的布局和样式文件

1.对话框头部的取消按钮样式：在drawable文件下创建一个btn_selector_exit.xml文件，在这里要注意一点item下的属性android:background=“#dedede”,这样直接写会报错，我这里用的是换颜色，所以我在string.xml文件下写了两个颜色，大家要注意一下，我有点想不通的是为什么background属性直接写颜色代码会出错，有点郁闷，如果你有好的解释也可以告诉我这个android的 菜鸟

<drawable name="pressed_color">#0cb026</drawable>

  <drawable name="default_color">#53cc66</drawable>

<?xml version="1.0" encoding="utf-8" ?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
  <item android:state_pressed="true" android:drawable="@drawable/exit_press"/>
  <item android:drawable="@drawable/exit"/>
</selector>

2.底部两个按钮按下换背景色的样式新建一个btn_selector_choose.xml文件

<?xml version="1.0" encoding="utf-8" ?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
  <item android:state_pressed="true"  android:drawable="@drawable/pressed_color"  />
  <item  android:drawable="@drawable/default_color"  />
</selector>

3.最重要的还是<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/layout_relative"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
<!--头部-->
    <RelativeLayout
        android:id="@+id/layout_title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:background="#53cc66"
        android:padding="5dp">
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_centerVertical="true"
            android:text="提示文本"
            android:textSize="18sp"
            android:textStyle="bold"
           android:textColor="#ffffff"
        />
        <Button
            android:id="@+id/btn_cancel"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_alignParentRight="true"
            android:background="@drawable/btn_selector_exit" />
    </RelativeLayout>
<!--中间内容-->
    <LinearLayout
        android:id="@+id/layout_detail"
        android:layout_height="wrap_content"
        android:layout_width="match_parent"
        android:layout_below="@+id/layout_title"
        android:layout_centerInParent="true"
        android:orientation="vertical"
       android:background="#f1f1f1"
        android:padding="20dp"
        >
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="通过setView方法定制alertDialog"
            android:textColor="#04AEDA"
            android:textSize="18sp" />
            <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="作者：张林"
            android:textColor="#04AEDA"
            android:textSize="18sp" />
    </LinearLayout>
<!--底部按钮-->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/layout_detail"
        android:orientation="horizontal"
        android:background="#f1f1f1"
        android:padding="5dp"
      >
        <Button
            android:id="@+id/btn_blog"
            android:layout_width="match_parent"
            android:layout_height="40dp"
            android:layout_weight="1"
            android:background="@drawable/btn_selector_choose"
            android:text="访问博客"
            android:textColor="#ffffff"
            android:textSize="20sp"
            android:layout_marginRight="5dp"
      />

         <Button
            android:id="@+id/btn_close"
            android:layout_width="match_parent"
            android:layout_height="40dp"
            android:layout_weight="1"
            android:background="@drawable/btn_selector_choose"
            android:text="关闭对话框"
            android:textColor="#ffffff"
            android:textSize="20sp" />

    </LinearLayout>
</RelativeLayout>

mainactivity代码，这个布局我就不贴了。

  public class MainActivity : Activity
    {
        private AlertDialog alertDialog = null;
        private AlertDialog.Builder builder = null;
        private Button btn_show = null;
        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);
            SetContentView(Resource.Layout.Main);
             bindViewClick();
            builder = new AlertDialog.Builder(this);
         
            LayoutInflater layoutInflater = LayoutInflater.From(this);
            var view_customer = layoutInflater.Inflate(Resource.Layout.view_dialog_custom, null, false);

            builder.SetView(view_customer);
            builder.SetCancelable(false);
            alertDialog = builder.Create();
            view_customer.FindViewById(Resource.Id.btn_cancel).Click += (s, e) =>
            {
                Toast.MakeText(this, "对话框已关闭", ToastLength.Short).Show();
                alertDialog.Dismiss();
            };
            view_customer.FindViewById(Resource.Id.btn_blog).Click += delegate
            {
                Toast.MakeText(this, "正在访问博客", ToastLength.Short).Show();
                Uri uri = Uri.Parse("http://blog.csdn.net/kebi007");
                Intent intent = new Intent(Intent.ActionView, uri);
                StartActivity(intent);
                alertDialog.Dismiss();
            };
            view_customer.FindViewById(Resource.Id.btn_close).Click += delegate
            {
                Toast.MakeText(this, "对话框已关闭", ToastLength.Short).Show();
                alertDialog.Dismiss();
            };

            btn_show = FindViewById<Button>(Resource.Id.btn_show);
            btn_show.Click += delegate { alertDialog.Show(); };
        }
    }

4.当然还有更高级的自定义的对话框，后面继续...........