Android UI学习 - GridView和ImageView的使用

核心提示：GridView: A view that shows items in two-dimensional scrolling grid. The items in the grid come from the ListAdapter associated with this view. 简单说，GridView就是我

GridView: A view that shows items in two-dimensional scrolling grid. The items in the grid come from the ListAdapter associated with this view. 简单说，GridView就是我们资源管理器平常见到的一个个文件的icon显示方式。

上面提及到了，GridView的Item是来自ListAdapter的，所以一般在Activity的onCreate使用GridView的代码：

@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.grid_2); GridView g = (GridView) findViewById(R.id.myGrid); g.setAdapter(new ImageAdapter(this)); }

而ImageAdapter一般是extends BaseAdapter。BaseAdapter是implements ListAdapter SpinnerAdapter，但很多时候自定义的Adapter都是override ListAdapter的父类Adapter接口里面的方法：

int getCount() 获取当前Adapter的Items数目

Object getItem(int position) 获取相应position的Item

long getItemId(int position) 获取相应position的Item在List中的row id

View getView(int position, View convertView, ViewGroup parent) 获取在指定position所要显示的data的View

这些方法函数和swing的差不多，都是基于MVC。大概原理过程是这样的：程序需要显示GridView，那么要把data一个一个地显示出来是通过一个for循环，首先call Adapter.getCount()得到有多少个data，然后position++地getItem，getView得到要显示的view,这样子逐一地显示出来!

下面是官方sample里面的Photo Grid的例子，本人省略了某些代码：

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 imageView; if (convertView == null) { imageView = new ImageView(mContext); imageView.setLayoutParams(new GridView.LayoutParams(45, 45));//设置ImageView宽高 imageView.setAdjustViewBounds(false); imageView.setScaleType(ImageView.ScaleType.CENTER_CROP); imageView.setPadding(8,