Android：Gallery控件之图片循环显示

先上图·····

1.进入程序


2、向右滑动


3、点击图片


4、向右滑动


5、再次点击右边图片，出现循环效果



实现步骤：
一、main.layout布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=""
    android:id="@+id/main"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

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

二、启动代码里初始化Gallery，这里主要用到Gallery控件的 setImageResource()[显示内容] 和 setLayoutParams()[显示属性] 方法。最最关键的是定制适配器 ImageShowAdapter。而实现循环是通过对position求余实现，Gallery开始时会调用getCount()函数，确定有多少个View要绘制，当绘制到最后一个以后就结束了。为了实现循环我们设置getCount()的返回值为Integer的最大值，这样Gallery就可以绘制足够多的View，但是我们设定的资源图片数组大小为4，要想循环当然要用到取模运算啦。

package com.adamhu.dianxiaoer;

import java.lang.reflect.Field;
import java.util.ArrayList;

import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageView;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;

public class EntryActivity extends Activity {

    private Gallery mGallery;
    private ImageView mImgView;
    private ImageShowAdapter mAdapter = new ImageShowAdapter(this);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_entry);

        mGallery = (Gallery) findViewById(R.id.gallery);
        mImgView = (ImageView) findViewById(R.id.image_view);
        try {
            mGallery.setAdapter(mAdapter);
        } catch (IllegalArgumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        mGallery.setOnItemClickListener(new AdapterView.OnItemClickListener(){
            public void onItemClick(AdapterView<?> parent, View v, int position, long id){
                Integer[] iView = mAdapter.getImagesId();
                mImgView.setImageDrawable(getResources().getDrawable(iView[position%iView.length]));
            }
        });

    }

    public class ImageShowAdapter extends BaseAdapter{

        private Context mContext;
        private ArrayList<Integer> imgList = new ArrayList<Integer>();
        private ArrayList<Object> imgSize = new ArrayList<Object>();

        public ImageShowAdapter(Context c){
            mContext = c;

        }

        @Override
        public int getCount() {
            // TODO Auto-generated method stub
            return Integer.MAX_VALUE;
        }

        @Override
        public Object getItem(int position) {
            // TODO Auto-generated method stub
            return position;
        }

        @Override
        public long getItemId(int position) {
            // TODO Auto-generated method stub
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            // TODO Auto-generated method stub
            ImageView i = new ImageView(mContext);
            i.setImageResource(mImagesId[position%mImagesId.length]);
            i.setLayoutParams(new Gallery.LayoutParams(270,190));
            return i;
        }

        public Integer[] getImagesId(){
            return mImagesId;
        }

        public void setImagesId(Integer[] mImagesId){
            this.mImagesId = mImagesId;
        }

        private Integer mImagesId[] = {
                R.drawable.image1,
                R.drawable.image10,
                R.drawable.image11,
                R.drawable.image12
        };

    }

}