android学习日记16--GridView(网格视图)

一、GridView

1、简述　　

　　GridView按照行列来显示图片或文本的一种视图，排列其实有点类似TableLayout布局，

不过和TableLayout还是差别很大的,倒比较像二维的ListView。位于android.widget包下，常常用来实现类似九宫格的图像。
实现手法和ListView有点相似，用Apapter把数据绑定到控件上，为容器提供子视图，利用视图的数据和元数据来构建每个子视图自定义Adapter显示。
如果需要自定义适配器 可以扩展抽象类BaseAdapter。

2、常用属性和对应方法如下：

下面用实例化SimpleAdapter和继承抽象类BaseAdapter方法实现下图的例子：

3、实例化SimpleAdapter实现

Activity代码：

     private GridView gv;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.gridview); 

        //准备要添加的数据条目
        List<Map<String, Object>> items = new ArrayList<Map<String,Object>>();
        for (int i = 0; i < 9; i++) {
          Map<String, Object> item = new HashMap<String, Object>();
          item.put("imageItem", R.drawable.ic_launcher);//添加图像资源的ID
          item.put("textItem", "icon" + i);//按序号添加ItemText
          items.add(item);
        } 

       //实例化SimpleAdapter适配器
        SimpleAdapter adapter = new SimpleAdapter(this,
                                                    items,
                                                    R.layout.grid_item,
                                                    new String[]{"imageItem", "textItem"},
                                                    new int[]{R.id.image_item, R.id.text_item}); 

        //获得GridView实例
        gv = (GridView)findViewById(R.id.mygridview);
        //为GridView设置适配器
        gv.setAdapter(adapter); 

     }

单个组件XML:

 <?xml version="1.0" encoding="utf-8"?>
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/RelativeLayout1"
    android:layout_width="wrap_content"
    android:layout_height="fill_parent"
    android:paddingBottom="6dip"
    >
    <ImageView
       android:id="@+id/image_item"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:layout_centerHorizontal="true"
       android:src="@drawable/ic_launcher"
       />
    <TextView
       android:id="@+id/text_item"
       android:layout_below="@+id/image_item"
       android:layout_height="wrap_content"
       android:layout_width="wrap_content"
       android:layout_centerHorizontal="true"
       />
 </RelativeLayout>

页面主布局XML：

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    >
    <GridView
       android:id="@+id/mygridview"
       android:numColumns="3"
       android:gravity="center_horizontal"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:stretchMode="columnWidth"
       />
 </LinearLayout>

4、继承抽象类BaseAdapter实现

替换成自己GridAdapter代码：

 //       //准备要添加的数据条目
 //       List<Map<String, Object>> items = new ArrayList<Map<String,Object>>();
 //       for (int i = 0; i < 9; i++) {
 //         Map<String, Object> item = new HashMap<String, Object>();
 //         item.put("imageItem", R.drawable.ic_launcher);//添加图像资源的ID
 //         item.put("textItem", "icon" + i);//按序号添加ItemText
 //         items.add(item);
 //       }
 //
 //      //实例化SimpleAdapter适配器
 //       SimpleAdapter adapter = new SimpleAdapter(this,
 //                                                   items,
 //                                                   R.layout.grid_item,
 //                                                   new String[]{"imageItem", "textItem"},
 //                                                   new int[]{R.id.image_item, R.id.text_item}); 

       List<GridInfo> list = new ArrayList<GridInfo>();
        for (int i = 0; i < 9; i++) {
            list.add(new GridInfo("icon"+i));
        } 

        GridAdapter adapter = new GridAdapter(this);
        adapter.setList(list);

补上GridAdapter代码：

 public class GridAdapter extends BaseAdapter {  

     private class GridHolder {
         ImageView appImage;
         TextView appName;
     }  

     private Context context;  

     private List<GridInfo> list;
     private LayoutInflater mInflater;  

     public GridAdapter(Context c) {
         super();
         this.context = c;
     }  

     public void setList(List<GridInfo> list) {
         this.list = list;
         mInflater = (LayoutInflater) context
                 .getSystemService(Context.LAYOUT_INFLATER_SERVICE);  

     }  

     public int getCount() {
         // TODO Auto-generated method stub
         return list.size();
     }  

     @Override
     public Object getItem(int index) {  

         return list.get(index);
     }  

     @Override
     public long getItemId(int index) {
         return index;
     }  

     @Override
     public View getView(int index, View convertView, ViewGroup parent) {
         GridHolder holder;
         if (convertView == null) {
             convertView = mInflater.inflate(R.layout.grid_item, null);
             holder = new GridHolder();
             holder.appImage = (ImageView)convertView.findViewById(R.id.image_item);
             holder.appName = (TextView)convertView.findViewById(R.id.text_item);
             convertView.setTag(holder);     

         }else{
              holder = (GridHolder) convertView.getTag();     

         }
         GridInfo info = list.get(index);
         if (info != null) {
             holder.appName.setText(info.getName());
         }
         return convertView;
     }

 }

比较麻烦还是重写getView()方法。里面的GridInfo只是普通的JAVA bean类。