用mvc的思想去理解 数据源，adapter，xxxView的关系，写代码就轻松多了
先写一个简单的gridview
第一版:只有图片
xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:paddingTop="10dp"
tools:context=".ActivityMain" ><GridView
android:id="@+id/gridView1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:numColumns="3"
android:columnWidth="90dp"
android:horizontalSpacing="10dp"
android:verticalSpacing="10dp"
android:stretchMode="spacingWidth"
>
</GridView></LinearLayout>
java代码
public class ActivityMain extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
GridView gridView = (GridView)findViewById(R.id.gridView1);
gridView.setAdapter( new MyGridviewAdapter(this) );
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
class MyGridviewAdapter extends BaseAdapter {
Context context; //传入ActivityMain给adapter，创建imageview的时候要用到
//做一个数组存图表的id
int []imagesId = {R.drawable.icon1,R.drawable.icon2,R.drawable.icon3,
R.drawable.icon4,R.drawable.icon5,R.drawable.icon6,
R.drawable.icon7,R.drawable.icon8,R.drawable.icon9};
MyGridviewAdapter(Context con) {
this.context = con;
}
@Override
public int getCount() {
return imagesId.length;
}
@Override
public Object getItem(int arg0) {
return arg0;
}
@Override
public long getItemId(int arg0) {
return arg0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
//这里重头戏，既然要getview，就返回一个图标的imageview给它
ImageView imgview = new ImageView(context);
imgview.setImageResource( imagesId[position] );
return imgview;
}
}
}
第二版:只有图片
上面的有点问题，看其他人的代码，会对convertView做一个null判断，避免重复创建，节约资源
改进
修改getview方法:
public View getView(int position, View convertView, ViewGroup parent) {
//这里重头戏，既然要getview，就返回一个图标的imageview给它
//ImageView imgview = new ImageView(context);
//imgview.setImageResource( imagesId[position] );
ImageView imgview;
if( convertView == null )
{
imgview = new ImageView(context);
imgview.setImageResource( imagesId[position] );
}
else
{
imgview = (ImageView)convertView;
}
return imgview;
}
长这样:
第三版: 图片 + 文字
首先自定义一个grid_one_item.xml，里面混和了图片和文字
<?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"
android:orientation="vertical" ><ImageView
android:id="@+id/grid_item_image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/><TextView
android:id="@+id/grid_item_text"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"/></LinearLayout>
java代码 重点理解适配器部分
public class ActivityMain extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
GridView gridView = (GridView)findViewById(R.id.gridView1);
gridView.setAdapter( new MyGridviewAdapter(this) );
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
//拥有textview的string内容 和imageview的资源id
class IconInfo {
String text;
int imageid;
}
//一个混合了textview和imageview的类
class MixedView {
ImageView imgview;
TextView textview;
}
class MyGridviewAdapter extends BaseAdapter {
Context context; //传入ActivityMain给adapter，创建view的时候要用到
LayoutInflater inflater;
List<IconInfo> iconInfoList;
//做一个数组存图表的id
int []imagesId = {R.drawable.icon1,R.drawable.icon2,R.drawable.icon3,
R.drawable.icon4,R.drawable.icon5,R.drawable.icon6,
R.drawable.icon7,R.drawable.icon8,R.drawable.icon9};
String []titles = {"标题1","标题2","标题3","标题4","标题5","标题6","标题7","标题8","标题9"};
MyGridviewAdapter(Context con) {
this.context = con;
inflater = LayoutInflater.from(context);
iconInfoList = new ArrayList<IconInfo>();
for(int i=0; i<imagesId.length; i++)
{
IconInfo iconInfo = new IconInfo();
iconInfo.imageid = imagesId[i];
iconInfo.text = titles[i];
iconInfoList.add(iconInfo);
}
}
@Override
public int getCount() {
return imagesId.length;
}
@Override
public Object getItem(int arg0) {
return arg0;
}
@Override
public long getItemId(int arg0) {
return arg0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
MixedView mixedView;
//用setTag() getTag() 来节约findViewById所消耗的性能
if( convertView == null )
{
convertView = inflater.inflate(R.layout.grid_one_item, null);
mixedView = new MixedView();
mixedView.imgview = (ImageView)convertView.findViewById(R.id.grid_item_image);
mixedView.textview = (TextView)convertView.findViewById(R.id.grid_item_text);
convertView.setTag(mixedView);
}
else
{
mixedView = (MixedView)convertView.getTag();
}
mixedView.imgview.setImageResource( iconInfoList.get(position).imageid );
mixedView.textview.setText( iconInfoList.get(position).text );
return convertView;
}
}
}
View
Code
个人粗俗地理解这两句(错了求指正):
convertView.setTag(mixedView); // 为convertView设定一个
指向mixedView的引用
mixedView= (MixedView) convertView.getTag(); //
把convertView所引用的对象赋给mixedView，
也就是说，convertView和mixedView引用的是同一个内存里的东西
//所以getview时
我们做处理的是mixedView，还可以返回convertView，因为他们引用的是同一个东西啊
最后长这样：
android:stretchMode 参考下图
更多参考:
http://liangruijun.blog.51cto.com/3061169/647355
http://www.cnblogs.com/topcoderliu/archive/2011/06/07/2074419.html
[Android学习系列13]关于Gridview的一些事,布布扣,bubuko.com