Android入门/GirdView(九)

利用GirdView显示九宫格

1 . 为GridView的每一项准备一个布局文件

2.   处理好数据,生成动态数组

3.   生成适配器, 用于装载每一个子项

4.   添加点击事件处理

5.  点击图片 更换其背景图片 以及绑定资源 更改资源图片

先上效果图

activity_main.xml

<?xml version="1.0" encoding="utf-8"?><GridView     xmlns:android="http://schemas.android.com/apk/res/android"     android:id="@+id/gridview"     android:layout_width="fill_parent"     android:layout_height="fill_parent"     android:numColumns="auto_fit"     android:verticalSpacing="10dp"     android:listSelector="@drawable/ic_launcher"     android:horizontalSpacing="10dp"     android:columnWidth="90dp"     android:stretchMode="columnWidth"     android:gravity="center"      />

相关属性

android:numColumns = "auto_fit"    自动调整显示列数

android:verticalSpacing ="10dp"  两行之间的间距

android:horizontalSpacing="10dp" 两列之间的间距

android:listSelector = "@drawable/xxx" GridView被选中时,显示背景资源

android:stretchMode  缩放与列宽大小同步

night.xml

<?xml version="1.0" encoding="utf-8"?><RelativeLayout    xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_height="wrap_content"    android:paddingBottom="4dp"    android:layout_width="fill_parent" >    <ImageView         android:layout_height="wrap_content"        android:layout_width="wrap_content"        android:id="@+id/ItemImage"        android:layout_centerHorizontal="true">    </ImageView>    <TextView                  android:layout_width="wrap_content"                  android:layout_below="@+id/ItemImage"                  android:layout_height="wrap_content"                  android:text="TextView"                  android:layout_centerHorizontal="true"                  android:id="@+id/ItemText">      </TextView>    </RelativeLayout>

Java代码

public class MainActivity extends Activity {private GridView gridview;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);/** 1. 处理好数据 , 生成动态数组*/gridview = (GridView)findViewById(R.id.gridview);// 生成动态数组 存数据ArrayList<HashMap<String, Object>> list = new ArrayList<HashMap<String,Object>>();for(int i=0;i<9;i++){HashMap<String, Object> map = new HashMap<String, Object>();map.put("ItemImage", R.drawable.ic_action_search);map.put("ItemText", "No."+i);//添加到动态数组list.add(map);}/**  2. 生成适配器  */SimpleAdapter simpleAdapter = new SimpleAdapter(this, list,//数据源R.layout.night,//Items 布局new String[]{"ItemImage","ItemText"},// 动态数组list 对应的子项的名称new int[]{R.id.ItemImage,R.id.ItemText}// night.xml 内对应组件的id);/** 3. gridview添加并且显示*/gridview.setAdapter(simpleAdapter);/** 4.添加消息处理*/gridview.setOnItemClickListener(listener);}private OnItemClickListener listener = new OnItemClickListener() {@Overridepublic void onItemClick(AdapterView<?> parent, //AdapterView被点击时发生View view, //AdapterView内被点击的视图int position,//适配器中的位置的视图long id)//被点击的项行的id {HashMap<String, Object> item = (HashMap<String, Object>)parent.getItemAtPosition(position);    //显示所选Item的ItemText  setTitle((String)item.get("ItemText"));//ImageView img = new ImageView(MainActivity.this);//img.setImageDrawable(getResources().getDrawable(R.drawable.ic_launcher));//img.invalidate(); }};    }

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Question : 那么如何实现 在OnItemClickListener点击时,更换被点击的图片呢 ?

                1. 上述代码是通过在GridView中,添加android:listSelector="@drawable/ic_launcher"达到点击更换背景图片的.

             2. 此时讲的是如何更换点击的图片,也就是数据源里装载的资源 ?

其实 只要重写一下Adapter下的getView方法就可以了,代码如下

public class MainActivity extends Activity {public PjdAdapter simpleAdapter;private GridView gridview;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);preInitUI();initUI();postInitUI();}//  准备数据源  private void preInitUI() {ArrayList<HashMap<String, Object>> list = new ArrayList<HashMap<String, Object>>();for (int i = 0; i < 9; i++) {HashMap<String, Object> map = new HashMap<String, Object>();map.put(PjdAdapter.IMAGE_KEY, R.drawable.ic_action_search);map.put(PjdAdapter.TEXT_KEY, "No." + i);// 添加到动态数组list.add(map);}simpleAdapter = new PjdAdapter(this, list, // 数据源R.layout.night, // Items 布局new String[] { "ItemImage", "ItemText" },// 动态数组list 对应的子项的名称new int[] { R.id.ItemImage, R.id.ItemText }// night.xml 内对应组件的id);}   //   UI private void initUI() {setContentView(R.layout.activity_main);gridview = (GridView) findViewById(R.id.gridview);}private void postInitUI() {gridview.setAdapter(simpleAdapter);gridview.setOnItemClickListener(listener);}private OnItemClickListener listener = new OnItemClickListener() {@SuppressWarnings("unchecked")public void onItemClick(AdapterView<?> parent, // AdapterView被点击时发生View view, // AdapterView内被点击的视图int position, // 适配器中的视图的位置long id) // 被点击的项行的id{HashMap<String, Object> item = (HashMap<String, Object>) parent.getItemAtPosition(position);// 显示所选Item的ItemTextsetTitle((String) item.get("ItemText"));Log.v("ONITEMCLICK", "position = " + position);simpleAdapter.setSelected(position);}};

适配器类

public class PjdAdapter extends SimpleAdapter {public final static String IMAGE_KEY = "ItemImage";public final static String TEXT_KEY = "ItemText";private List<HashMap<String, Object>> list;private int selected = -1;private Context context;// 继承父类的构造public PjdAdapter(Context context, List<HashMap<String, Object>> data,int resource, String[] from, int[] to) {super(context, data, resource, from, to);this.context = context;this.list = data;}// 获取当前点击的位置public void setSelected(int position) {this.selected = position;notifyDataSetChanged();}// 获得Items的数量public int getCount() {if (list == null) {return 0;} else {return this.list.size();}}// 根据ListView位置返回Viewpublic Object getItem(int position) {return this.list.get(position);}// 根据ListView位置得到List中的IDpublic long getItemId(int position) {return position;}// 根据位置得到View对象 3个参数[ List中的ID ],[ Items的视图 ],[ 父类的视图 ]public View getView(int position, View convertView, ViewGroup parent) {Log.v("getView", "position = " + position);ViewHolder viewHolder = null;if(convertView == null){convertView = inflateView();}viewHolder = (ViewHolder)convertView.getTag();viewHolder.init(convertView);viewHolder.fillFromItem(list.get(position),selected == position);return convertView;}private View inflateView() {LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);View view = inflater.inflate(R.layout.night, null);view.setTag(new ViewHolder());return view;}}class ViewHolder {ImageView imageView;TextView textView;public void init(View view) {imageView = (ImageView) view.findViewById(R.id.ItemImage);textView = (TextView) view.findViewById(R.id.ItemText);}public void fillFromItem(HashMap<String, Object> map, boolean isSpecial) {if (isSpecial) {imageView.setImageResource(R.drawable.ic_launcher);textView.setText(R.string.app_name);}else{imageView.setImageResource((Integer)map.get(PjdAdapter.IMAGE_KEY));textView.setText((String)map.get(PjdAdapter.TEXT_KEY));}}}

Question : 那么如何实现 点击不同的Items 执行不同的事件呢?

intent it=null;switch(arg2){   case 0:  it=new Intent(mainform.this,  1.class); break;   case 1: it=new Intent(mainform.this,  2.class); break;  }startActivity(it);