Android入门第十二篇之Gallery

Android的Gallery控件是个很不错的看图控件，大大减轻了开发者对于看图功能的开发，而且效果也比较美观。本文介绍Gallery的用法，用反射机制来动态读取资源中的图片。

本文的效果图：

main.xml源码:

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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"
>
< Gallery android:id = "@+id/gallery" android:layout_height = "fill_parent" android:layout_width = "fill_parent" > </ Gallery >
</ LinearLayout >

程序源码：

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package com.testImageView;
import java.lang.reflect.Field;
import java.util.ArrayList;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageView;
import android.widget.AdapterView.OnItemClickListener;
public class testImageView extends Activity{
private GallerymGallery;
@Override
public void onCreate(BundlesavedInstanceState){
super .onCreate(savedInstanceState);
setContentView(R.layout.main);
mGallery=(Gallery)findViewById(R.id.gallery);
try {
mGallery.setAdapter(new ImageAdapter( this ));
}catch (IllegalArgumentExceptione){
//TODOAuto-generatedcatchblock
e.printStackTrace();
}catch (IllegalAccessExceptione){
//TODOAuto-generatedcatchblock
e.printStackTrace();
}
mGallery.setOnItemClickListener(new OnItemClickListener(){
public void onItemClick(AdapterViewparent,Viewv, int position, long id){
testImageView.this .setTitle(String.valueOf(position));
}
});
}
/*
*classImageAdapterisusedtocontrolgallerysourceandoperation.
*/
private class ImageAdapter extends BaseAdapter{
private ContextmContext;
private ArrayList<Integer>imgList= new ArrayList<Integer>();
private ArrayList<Object>imgSizes= new ArrayList<Object>();
public ImageAdapter(Contextc) throws IllegalArgumentException,IllegalAccessException{
mContext=c;
//用反射机制来获取资源中的图片ID和尺寸
Field[]fields=R.drawable.class .getDeclaredFields();
for (Fieldfield:fields)
{
if (! "icon" .equals(field.getName())) //除了icon之外的图片
{
int index=field.getInt(R.drawable. class );
//保存图片ID
imgList.add(index);
//保存图片大小
int size[]= new int [ 2 ];
BitmapbmImg=BitmapFactory.decodeResource(getResources(),index);
size[0 ]=bmImg.getWidth();size[ 1 ]=bmImg.getHeight();
imgSizes.add(size);
}
}
}
@Override
public int getCount(){
//TODOAuto-generatedmethodstub
return imgList.size();
}
@Override
public ObjectgetItem( int position){
//TODOAuto-generatedmethodstub
return position;
}
@Override
public long getItemId( int position){
//TODOAuto-generatedmethodstub
return position;
}
@Override
public ViewgetView( int position,ViewconvertView,ViewGroupparent){
//TODOAuto-generatedmethodstub
ImageViewi=new ImageView(mContext);
//从imgList取得图片ID
i.setImageResource(imgList.get(position).intValue());
i.setScaleType(ImageView.ScaleType.FIT_XY);
//从imgSizes取得图片大小
int size[]= new int [ 2 ];
size=(int [])imgSizes.get(position);
i.setLayoutParams(new Gallery.LayoutParams(size[ 0 ],size[ 1 ]));
return i;
}
};
}

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