android：gallery

①　新建项目
②　定义layout 外部resource 的xml 文件，用来改变layout 的背景


<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="Gallery">
        <attr name="android:galleryItemBackground" />
    </declare-styleable>
    <!-- 定义layout 外部resource 的xml 文件，用来改变layout 的背景图。 -->
</resources>


③　修改main.xml布局，添加一个Gallery和一个ImageView

<?xml version="1.0" encoding="utf-8"?>
<AbsoluteLayout
    android:id="@+id/widget_absolutelayout"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    xmlns:android="http://schemas.android.com/apk/res/android"
>
<Gallery
    android:layout_width="fill_parent"
    android:layout_height="143px"
    android:layout_x="0px"
    android:layout_y="51px"
    android:id="@+id/Gallery_preView">
</Gallery>
<ImageView
    android:layout_width="239px"
    android:layout_height="218px"
    android:layout_x="38px"
    android:layout_y="184px"
    android:id="@+id/ImageView_photo">
</ImageView>
</AbsoluteLayout>


④　新建一个myImageAdapter类--Gallery的适配器，它继承于BaseAdapter类.

package zyf.Ex_Ctrl_10ME;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
public class myImageAdapter extends BaseAdapter {
@Override
public int getCount() {
// TODO Auto-generated method stub
return 0;
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return null;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
return null;
}
}


⑤　修改mainActivity.java，添加Gallery相关操作


package zyf.Ex_Ctrl_10ME;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Gallery;
import android.widget.ImageView;
import android.widget.Toast;

public class Ex_Ctrl_10ME extends Activity {
    /** Called when the activity is first created. */
/*定义要使用的对象*/
private Gallery gallery;
private ImageView imageview;
private myImageAdapter imageadapter;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        imageadapter=new myImageAdapter(this);
        /* 通过findViewById 取得 资源对象*/
        gallery=(Gallery)findViewById(R.id.Gallery_preView);
        imageview=(ImageView)findViewById(R.id.ImageView_photo);
        /*给Gallery设置适配器 把Ex_Ctrl_10ME类传入参数*/
        gallery.setAdapter(imageadapter);
        /*设置Gallery的点击事件监听器*/
        gallery.setOnItemClickListener(new Gallery.OnItemClickListener(){
@Override
public void onItemClick(AdapterView<?> parent, View v, int position,
long id) {
// TODO Auto-generated method stub
/*显示该图片是几号*/
Toast.makeText(Ex_Ctrl_10ME.this,
                         "这是图片："+position+"号", Toast.LENGTH_SHORT).show();

/*设置大图片*/
imageview.setBackgroundResource(imageadapter.myImageIds[position]);
}
        });
    }
}


⑥　修改myImageAdapter.java文件，实现相簿浏览效果


package zyf.Ex_Ctrl_10ME;

import android.content.Context;
import android.content.res.TypedArray;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageView;

public class myImageAdapter extends BaseAdapter{//自定义的类变量
/*变量声明*/
int mGalleryItemBackground;
private Context context;//上下文
/* 构建一Integer array 并取得预加载Drawable 的图片id */
public Integer[] myImageIds = { R.drawable.photo1, R.drawable.photo2,
R.drawable.photo3, R.drawable.photo4, R.drawable.photo5,
R.drawable.photo6, };
/*自定义的构造方法*/
public myImageAdapter(Context context) {
// TODO Auto-generated constructor stub
this.context=context;
/*
* 使用在res/values/attrs.xml 中的<declare-styleable>定义 的Gallery 属性.
*/
TypedArray typed_array=context.obtainStyledAttributes(R.styleable.Gallery);
/* 取得Gallery 属性的Index id */
mGalleryItemBackground=typed_array.getResourceId(R.styleable.Gallery_android_galleryItemBackground, 0);
/* 让对象的styleable 属性能够反复使用 */
typed_array.recycle();
}
/* 重写的方法getCount,返回图片数目 */
@Override
public int getCount() {
// TODO Auto-generated method stub
return myImageIds.length;
}
/* 重写的方法getItemId,返回图像的数组id */
@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;
}
/* 重写的方法getView,返回一View 对象 */
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
/* 产生ImageView 对象 */
ImageView imageview = new ImageView(context);
/* 设置图片给imageView 对象 */
imageview.setImageResource(myImageIds[position]);
/* 重新设置图片的宽高 */
imageview.setScaleType(ImageView.ScaleType.FIT_XY);
/* 重新设置Layout 的宽高 */
imageview.setLayoutParams(new Gallery.LayoutParams(128, 128));
/* 设置Gallery 背景图 */
imageview.setBackgroundResource(mGalleryItemBackground);
/* 返回imageView 对象 */
return imageview;
}
}