玩转Android---UI篇---Gallery（画廊视图）
Gallery能够水平显示其内容，一般用来浏览图片，被选中的选项位于中间，并且可以相应事件显示信息。下面结合ImageSwitcher组件来实现一个通过缩略图来浏览图片的程序，具体步骤如下
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第一步：
创建一个Andorid工程"GalleryTest”，该工程的入口是Activity类GalleryTest继承Activity并实现OnItemSelectedListener和ViewFactory接口，来实现图片和视图的创建
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package org.hualang.Gallery;import android.app.Activity;import android.os.Bundle;import android.view.View;import android.widget.AdapterView;import android.widget.AdapterView.OnItemSelectedListener;import android.widget.ViewSwitcher.ViewFactory;//继承Activity，实现onItemSelectedListener和ViewFactory接口public class GalleryTest extends Activity implements OnItemSelectedListener,ViewFactory{ /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } @Override public View makeView() { // TODO Auto-generated method stub return null; } @Override public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3) { // TODO Auto-generated method stub } @Override public void onNothingSelected(AdapterView<?> arg0) { // TODO Auto-generated method stub }}?第二步：
在工程的res\drawable\目录下添加7张图片和对应的缩略图
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第三步：
在工程res\layout\目录下创建一个布局文件main.xml，在其中那个添加一个Gallery组件和一个ImageSwitcher组件，并设置相应的属性
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<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <ImageSwitcher android:id="@+id/switcher" android:layout_width="fill_parent" android:layout_height="fill_parent" android:layout_alignParentTop="true" android:layout_alignParentLeft="true" /> <Gallery android:id="@+id/gallery" android:background="#55000000" android:layout_width="fill_parent" android:layout_height="60dp" android:layout_alignParentBottom="true" android:layout_alignParentLeft="true" android:gravity="center_vertical" android:spacing="16dp" /></LinearLayout>
?第四步：
在GalleryTest顶部声明使用到的ImageSwitcher实例图片资源Integer数组
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public class GalleryTest extends Activity implements OnItemSelectedListener,ViewFactory{ /** Called when the activity is first created. */ //声明ImageSwitcher private ImageSwitcher switcher; //缩略图片id数组 private Integer[] thumbids={ R.drawable.thumb0, R.drawable.thumb1, R.drawable.thumb2, R.drawable.thumb3, R.drawable.thumb4, R.drawable.thumb5, R.drawable.thumb6, R.drawable.thumb7 }; //图片id数组 private Integer[] imgids={ R.drawable.img0, R.drawable.img1, R.drawable.img2, R.drawable.img3, R.drawable.img4, R.drawable.img5, R.drawable.img6, R.drawable.img7 };?第五步：
在GalleryTest的onCreate()方法中，将窗口样式设置为无标题，设置当前布局视图，获得ImageSwitcher实例，并设置渐进渐出动画，获得Gallery实例
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public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //设置窗口特征无标题 requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(R.layout.main); //通过findViewById方法获得ImageSwitcher对象 switcher=(ImageSwitcher)findViewById(R.id.switcher); //为ImageSwitcher设置工厂 switcher.setFactory(this); //设置动画渐入效果 switcher.setInAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_in)); //设置动画渐出效果 switcher.setOutAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_out)); //通过findViewById方法获得Gallery对象 Gallery g=(Gallery)findViewById(R.id.gallery); }?第六步：
创建内部类ImageAdapter，该类继承BaseAdapter，为Gallery设置Adapter实例
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public class ImageAdapter extends BaseAdapter { //构造方法 public ImageAdapter(Context c) { mContext = c; } //获得数量 public int getCount() { return thumbids.length; } //获得当前选项 public Object getItem(int position) { return position; } //获得当前选项ID public long getItemId(int position) { return position; } //获得View对象 public View getView(int position, View convertView, ViewGroup parent) { //实例化ImageView对象 ImageView i = new ImageView(mContext); //设置缩略图片资源 i.setImageResource(thumbids[position]); //设置边界对齐 i.setAdjustViewBounds(true); //设置布局参数 i.setLayoutParams(new Gallery.LayoutParams( LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); //设置背景资源 i.setBackgroundResource(R.drawable.picturefrom); return i; } private Context mContext; }?第七步：
实现onItemSelected()方法，更换图片
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@Override public void onItemSelected(AdapterView<?> adapter, View v, int position, long id) { switcher.setImageResource(imgids[position]); }?第八步：
实现makeView()方法，为ImageView设置布局格式
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@Override public View makeView() { // TODO Auto-generated method stub //创建ImageView ImageView i=new ImageView(this); //设置背景颜色 i.setBackgroundColor(0xFF000000); //设置精度类型 i.setScaleType(ImageView.ScaleType.FIT_CENTER); //设置布局参数 i.setLayoutParams(new ImageSwitcher.LayoutParams( LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT)); return i; }?第九步：
为Gallery添加Adapter并添加OnItemSelectedListener监听器
g.setAdapter(new ImageAdapter(this)); g.setOnItemSelectedListener(this);?
至此，全部，结束，运行结果如下
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完整源代码：
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package org.hualang.Gallery;import android.app.Activity;import android.content.Context;import android.os.Bundle;import android.view.View;import android.view.ViewGroup;import android.view.Window;import android.view.animation.AnimationUtils;import android.widget.AdapterView;import android.widget.BaseAdapter;import android.widget.Gallery;import android.widget.ImageSwitcher;import android.widget.ImageView;import android.widget.AdapterView.OnItemSelectedListener;import android.widget.Gallery.LayoutParams;import android.widget.ViewSwitcher.ViewFactory;public class GalleryTest extends Activity implements OnItemSelectedListener, ViewFactory { private ImageSwitcher mSwitcher; private Integer[] mThumbIds = { R.drawable.thumb0, R.drawable.thumb1, R.drawable.thumb2, R.drawable.thumb3, R.drawable.thumb4, R.drawable.thumb5, R.drawable.thumb6, R.drawable.thumb7 }; private Integer[] mImageIds = { R.drawable.img0, R.drawable.img1, R.drawable.img2, R.drawable.img3, R.drawable.img4, R.drawable.img5, R.drawable.img6, R.drawable.img7 }; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(R.layout.main); mSwitcher = (ImageSwitcher) findViewById(R.id.switcher); mSwitcher.setFactory(this); mSwitcher.setInAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_in)); mSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_out)); Gallery g = (Gallery) findViewById(R.id.gallery); g.setAdapter(new ImageAdapter(this)); g.setOnItemSelectedListener(this); } public class ImageAdapter extends BaseAdapter { public ImageAdapter(Context c) { mContext = c; } public int getCount() { return mThumbIds.length; } public Object getItem(int position) { return position; } public long getItemId(int position) { return position; } public View getView(int position, View convertView, ViewGroup parent) { ImageView i = new ImageView(mContext); i.setImageResource(mThumbIds[position]); i.setAdjustViewBounds(true); i.setLayoutParams(new Gallery.LayoutParams( LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); i.setBackgroundResource(R.drawable.picturefrom); return i; } private Context mContext; } @Override public void onItemSelected(AdapterView<?> adapter, View v, int position, long id) { mSwitcher.setImageResource(mImageIds[position]); } @Override public void onNothingSelected(AdapterView<?> arg0) { } @Override public View makeView() { ImageView i = new ImageView(this); i.setBackgroundColor(0xFF000000); i.setScaleType(ImageView.ScaleType.FIT_CENTER); i.setLayoutParams(new ImageSwitcher.LayoutParams( LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT)); return i; }}??<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent"> <ImageSwitcher android:id="@+id/switcher" android:layout_width="fill_parent" android:layout_height="fill_parent" android:layout_alignParentTop="true" android:layout_alignParentLeft="true" /> <Gallery android:id="@+id/gallery" android:background="#55000000" android:layout_width="fill_parent" android:layout_height="60dp" android:layout_alignParentBottom="true" android:layout_alignParentLeft="true" android:gravity="center_vertical" android:spacing="16dp" /></RelativeLayout>?