Gallery可以显示一系列的图片，并且可以横向滑动。下面展示如何使用Gallery去显示一系列的图片。
1. 创建一个工程，Gallery。
2. main.xml中的代码。
[html]
<?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="fill_parent"
android:orientation="vertical" >
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Images of San Francisco" />
<Gallery
android:id="@+id/gallery1"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<ImageView
android:id="@+id/image1"
android:layout_width="320dp"
android:layout_height="250dp"
android:scaleType="fitXY" />
</LinearLayout>
3. 在res/values文件夹下面新建一个文件，attrs.xml。
4. attrs.xml中的代码。
[html]
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="Gallery1">
<attr name="android:galleryItemBackground" />
</declare-styleable>
</resources>
5. 准备一些图片。将这些图片放在res/drawable-mdpi下面。
6. GalleryActivity.java中的代码。
[java]
public class GalleryActivity extends Activity {
Integer[] imageIDs = {
R.drawable.pic1,
R.drawable.pic2,
R.drawable.pic3,
R.drawable.pic4,
R.drawable.pic5,
R.drawable.pic6,
R.drawable.pic7
};
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Gallery gallery = (Gallery) findViewById(R.id.gallery1);
gallery.setAdapter(new ImageAdapter(this));
gallery.setOnItemClickListener(new OnItemClickListener()
{
public void onItemClick(AdapterView<?> parent, View v,
int position, long id)
{
Toast.makeText(getBaseContext(),
"pic" + (position + 1) + " selected",
Toast.LENGTH_SHORT).show();
ImageView imageView = (ImageView) findViewById(R.id.image1);
imageView.setImageResource(imageIDs[position]);
}
});
}
public class ImageAdapter extends BaseAdapter
{
Context context;
int itemBackground;
public ImageAdapter(Context c)
{
context = c;
//---setting the style---
TypedArray a = obtainStyledAttributes(R.styleable.Gallery1);
itemBackground = a.getResourceId(
R.styleable.Gallery1_android_galleryItemBackground, 0);
a.recycle();
}
//---returns the number of images---
public int getCount() {
return imageIDs.length;
}
//---returns the item---
public Object getItem(int position) {
return position;
}
//---returns the ID of an item---
public long getItemId(int position) {
return position;
}
//---returns an ImageView view---
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null) {
imageView = new ImageView(context);
imageView.setImageResource(imageIDs[position]);
imageView.setScaleType(ImageView.ScaleType.FIT_XY);
imageView.setLayoutParams(new Gallery.LayoutParams(150, 120));
} else {
imageView = (ImageView) convertView;
}
imageView.setBackgroundResource(itemBackground);
return imageView;
}
}
}
7. 按F11在模拟器上面调试。会看见一系列的图片，这些图片可以左右滑动。当单击单个图片的时候，会弹出消息。
首先，我们在main.xml中添加Gallery和ImageView控件：
[html]
<Gallery
android:id="@+id/gallery1"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<ImageView
android:id="@+id/image1"
android:layout_width="320dp"
android:layout_height="250dp"
android:scaleType="fitXY" />
前面已经提到过，Gallery用来显示一系列的图片，ImageView用来显示被选中的图片。
这些图片的id被保存在imageIDs数组中：
[java]
Integer[] imageIDs = {
R.drawable.pic1,
R.drawable.pic2,
R.drawable.pic3,
R.drawable.pic4,
R.drawable.pic5,
R.drawable.pic6,
R.drawable.pic7
};
接下来创建BaseAdapter的子类：ImageAdapter，这样一来，我们就能把Gallery与图片资源绑定在一起了。这个适配器起到了桥梁的作用。
使用BaseAdapter的视图的还有：
ListView
GridView
Spinner
Gallery
BaseAdapter也有一些子类：
ListAdapter
ArrayAdapter
CursorAdapter
SpinnerAdapter
在ImageAdapter中我们主要实现以下的方法：
[java]
public class ImageAdapter extends BaseAdapter
{
Context context;
int itemBackground;
public ImageAdapter(Context c)
{
context = c;
//---setting the style---
TypedArray a = obtainStyledAttributes(R.styleable.Gallery1);
itemBackground = a.getResourceId(
R.styleable.Gallery1_android_galleryItemBackground, 0);
a.recycle();
}
//---returns the number of images---
public int getCount() {
return imageIDs.length;
}
//---returns the item---
public Object getItem(int position) {
return position;
}
//---returns the ID of an item---
public long getItemId(int position) {
return position;
}
//---returns an ImageView view---
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null) {
imageView = new ImageView(context);
imageView.setImageResource(imageIDs[position]);
imageView.setScaleType(ImageView.ScaleType.FIT_XY);
imageView.setLayoutParams(new Gallery.LayoutParams(150, 120));
} else {
imageView = (ImageView) convertView;
}
imageView.setBackgroundResource(itemBackground);
return imageView;
}
}
