Android开发之AlertDialog对话框内gallery的应用案例

案例功能：

      点击一个ImageButton图片按钮，显示有Gallery画廊的图片选择对话框,选择其中一个图片，确定后将选择的图片显示在按钮上

1：先编写首页布局代码ACTIVITY_MAIN.XML

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< RelativeLayout xmlns:android = "http://schemas.android.com/apk/res/android"      xmlns:tools = "http://schemas.android.com/tools"      android:layout_width = "match_parent"      android:layout_height = "match_parent" >                                                        < ImageButton          android:id = "@+id/imageButton"          android:layout_width = "100dp"          android:layout_height = "80dp"          android:layout_alignParentLeft = "true"          android:layout_alignParentTop = "true"          android:scaleType = "fitCenter"          android:src = "@drawable/ic_launcher" />                                                        < EditText          android:layout_width = "match_parent"          android:layout_height = "wrap_content"          android:layout_marginLeft = "14dp"          android:layout_toRightOf = "@+id/imageButton"          android:inputType = "text" >       </ EditText >                                                   </ RelativeLayout >

2：编写MainActivity.java    查找组件关键代码如下：

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//查找图片按钮组件  imagebutton = (ImageButton) this .findViewById(R.id.imageButton);  //注册监听  imagebutton.setOnClickListener( new View.OnClickListener() {                                                             @Override              public void onClick(View v) {                   //点击时显示对话框                   showDialog(IMAGES);                                                                             }           });

3：在layout下新建一个布局xml文件，我的文件为：pictures.xml,代码如下：

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<? xml version = "1.0" encoding = "utf-8" ?>  < LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android"      android:layout_width = "match_parent"      android:layout_height = "match_parent"      android:orientation = "vertical" >                                                 < Gallery          android:id = "@+id/gallery"          android:layout_width = "match_parent"          android:layout_height = "wrap_content"          android:background = "#55000000"          android:spacing = "10dp"          android:unselectedAlpha = "1.0" />                                            </ LinearLayout >

4：（1）对话框的创建和显示

      （2）LayoutInflater类将布局文件pictures.xml变为一个View实例。

               用builder.setView（）方法放置到Dialog里面去

注意关键点：必须查找设置对话框里的View里的gallery组件

 

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finalView view = inflater.inflate(R.layout.pictures,null );                          gallery=(Gallery) view.findViewById(R.id.gallery);

 

重写onCreateDialog()方法，创建有gallery的对话框

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@Override      protected Dialog onCreateDialog( int id) {       AlertDialog.Builder builder = new AlertDialog.Builder(                   MainActivity. this );           //创建LayoutInflater类用于实例xml文件为View类型           LayoutInflater inflater = LayoutInflater                   .from(MainActivity. this );           final View view = inflater.inflate(R.layout.pictures, null );                   //设置对话框标题           builder.setTitle( "请选择你的头像：" );                   //实例的xml文件添加到对话框里面           builder.setView(view);                   //查找对话框里xml内的gallery组件           gallery=(Gallery) view.findViewById(R.id.gallery);                   //设置画廊默认选择的图片           gallery.setSelection(pics.length / 2 );                   //设置适配器，ImageAdapter类继承BaseAdapter重写getView（）方法           gallery.setAdapter( new ImageAdapter());                   //处理gallery图片点击事件           gallery.setOnItemClickListener( new AdapterView.OnItemClickListener() {           @Override          public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {               //改变图片的位置为用户选择的图片位置                         pos = arg2;               }           });                                                                         //添加取消按钮，点击时关闭对话框removeDialog（）           builder.setNegativeButton( "取消" ,               new DialogInterface.OnClickListener() {                       @Override                      public void onClick(DialogInterface dialog, int which) {                       removeDialog(IMAGES);  ;                   }                   });           builder.setPositiveButton( "确定" ,               new DialogInterface.OnClickListener() {                                                   @Override              public void onClick(DialogInterface dialog, int which) {               removeDialog(IMAGES);               //设置用户选择图片后显示到图片按钮上                                        imagebutton.setImageResource(pics[pos]);                       }                   });                    //创建对话框，显示对话框时调用showDialog（）方法              return builder.create();

5：gallery适配器ImageAdapter的代码

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private class ImageAdapter extends BaseAdapter {                            @Override          public int getCount() {               return pics.length;           }                            @Override          public Object getItem( int position) {               return position;           }                            @Override          public long getItemId( int position) {               return position;           }                            @Override          public View getView( int position, View convertView, ViewGroup parent) {               ImageView img = new ImageView(MainActivity. this );               // 设置图片资源               img.setImageResource(pics[position]);               // 保持宽高比,不设置则gallery显示一张图片               img.setAdjustViewBounds( true );               // 设置固定大小               img.setMaxHeight( 80 );               img.setMaxWidth( 120 );               img.setScaleType(ImageView.ScaleType.FIT_CENTER);               // 设置图片大小               img.setLayoutParams( new Gallery.LayoutParams(                       LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));               return img;           }                        }

6：完整java代码

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public class MainActivity extends Activity {       private ImageButton imagebutton;       private Gallery gallery;       private int [] pics = { R.drawable.a, R.drawable.b, R.drawable.c,               R.drawable.d, R.drawable.e, R.drawable.f, R.drawable.g };       int pos = pics.length / 2 ;       int IMAGES= 1 ;       @Override      public void onCreate(Bundle savedInstanceState) {           super .onCreate(savedInstanceState);           setContentView(R.layout.activity_main);           imagebutton = (ImageButton) this .findViewById(R.id.imageButton);           imagebutton.setOnClickListener( new View.OnClickListener() {               @Override              public void onClick(View v) {                   showDialog(IMAGES);               }           });       }       @Override      protected Dialog onCreateDialog( int id) {           AlertDialog.Builder builder = new AlertDialog.Builder(                   MainActivity. this );           LayoutInflater inflater = LayoutInflater                   .from(MainActivity. this );           final View view = inflater.inflate(R.layout.pictures, null );           builder.setTitle( "请选择你的头像：" );           builder.setView(view);           gallery=(Gallery) view.findViewById(R.id.gallery);           gallery.setSelection(pics.length / 2 );           gallery.setAdapter( new ImageAdapter());           gallery.setOnItemClickListener( new AdapterView.OnItemClickListener() {               @Override              public void onItemClick(AdapterView<?> arg0, View arg1,                       int arg2, long arg3) {                   pos = arg2;               }           });           builder.setNegativeButton( "取消" ,                   new DialogInterface.OnClickListener() {                       @Override                      public void onClick(DialogInterface dialog,                               int which) {                           removeDialog(IMAGES);  ;                   }                   });           builder.setPositiveButton( "确定" ,                   new DialogInterface.OnClickListener() {                       @Override                      public void onClick(DialogInterface dialog,                               int which) {                           removeDialog(IMAGES);                           imagebutton.setImageResource(pics[pos]);                       }                   });           return builder.create();       }       private class ImageAdapter extends BaseAdapter {           @Override          public int getCount() {               return pics.length;           }           @Override          public Object getItem( int position) {               return position;           }           @Override          public long getItemId( int position) {               return position;           }           @Override          public View getView( int position, View convertView, ViewGroup parent) {               ImageView img = new ImageView(MainActivity. this );               // 设置图片资源               img.setImageResource(pics[position]);               // 保持宽高比,不设置则gallery显示一张图片               img.setAdjustViewBounds( true );               // 设置固定大小               img.setMaxHeight( 80 );               img.setMaxWidth( 120 );               img.setScaleType(ImageView.ScaleType.FIT_CENTER);               // 设置图片大小               img.setLayoutParams( new Gallery.LayoutParams(                       LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));               return img;           }       }       @Override      public boolean onCreateOptionsMenu(Menu menu) {           getMenuInflater().inflate(R.menu.activity_main, menu);           return true ;       }                 }

7：效果图

选择黄头发女孩时，图片滑到中间，点击确定