6.1.5 GridView详解

阅读更多 Android中的数据能够通过GridView类实现表格化展现，它也属于列表类型的控件，其继承关系如下：
java.lang.Object
   ↳ android.view.View
     ↳ android.view.ViewGroup
       ↳ android.widget.AdapterView
         ↳ android.widget.AbsListView
           ↳ android.widget.GridView
GridView控件应用案例效果如图6-10所示。

图6-10 GridView控件使用效果图
程序代码请参考代码清单6-8：
【代码清单6-8】 chapter6_4/src/com/work/GridView_1.java

public class GridView_1 extends Activity {@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.grid);GridView g = (GridView) findViewById(R.id.myGrid);g.setAdapter(new ImageAdapter(this));g.setOnItemSelectedListener(new OnItemSelectedListener() {public void onItemSelected(AdapterView<?> parent, View view,int position, long id) {Toast.makeText(GridView_1.this, "图片ID：" + mThumbIds[position],Toast.LENGTH_SHORT).show();}public void onNothingSelected(AdapterView<?> parent) {}});}private Integer[] mThumbIds = { R.drawable.yellowimage,R.drawable.redimage, R.drawable.icon, R.drawable.blueimage,R.drawable.photo1962, R.drawable.photo189, R.drawable.photo1803,R.drawable.photo1796, R.drawable.photo1732, R.drawable.photo1553,R.drawable.photo1537, R.drawable.photo1503, R.drawable.photo1453,R.drawable.photo1450, R.drawable.photo1447, R.drawable.photo1441,R.drawable.photo1433, R.drawable.photo1432, R.drawable.photo1431,R.drawable.photo1426, R.drawable.photo1425, R.drawable.photo1424,R.drawable.photo1423, R.drawable.photo1422, R.drawable.photo142,R.drawable.photo140, R.drawable.photo1220, R.drawable.photo1208,R.drawable.photo1207, R.drawable.photo101209, };public class ImageAdapter extends BaseAdapter {private Context mContext;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(60, 60));imageView.setPadding(8, 8, 8, 8);} else {imageView = (ImageView) convertView;}imageView.setImageResource(mThumbIds[position]);return imageView;}}}

代码的关键是实现BaseAdapter适配器类——ImageAdapter，代码如下：

public View getView(int position, View convertView, ViewGroup parent) {ImageView imageView;if (convertView == null) {imageView = new ImageView(mContext);imageView.setLayoutParams(new GridView.LayoutParams(60, 60));imageView.setPadding(8, 8, 8, 8);} else {imageView = (ImageView) convertView;}imageView.setImageResource(mThumbIds[position]);return imageView;}

在convertView为null的时候实例化控件，imageView.setLayoutParams(new GridView.LayoutParams(60, 60)是设置一个单元格中图片大小是60×60像素。imageView.setPadding(8, 8, 8, 设定GridView的单元格与其中的图片之间上、下、左、右空白。
布局文件chapter6_4/res/layout/grid.xml：

<?xml version="1.0" encoding="utf-8"?>

android:verticalSpacing="10dp"是两行之间的边距，android:horizontalSpacing="10dp"是两列之间的边距。android:numColumns="auto_fit"GridView列数设置为自动，android:columnWidth="60dp"是每列的宽度，也就是项目的宽度。android:gravity="center"是居中。
出自《Android开发案例驱动教程》第六章

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