您必须在 ViewPager 中使用 GridView。因此,在您的 MainActivity 中,您将拥有此布局。
创建 activity_main.xml 布局
这是主要布局。一切都将存在于其中,包括您的片段和标签。
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.myapp.gridview.MainActivity" />
创建您的 MainActivity.java 类
public class MainActivity extends ActionBarActivity implements ActionBar.TabListener
{
SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {@link ViewPager} that will host the section contents.
*/
ViewPager mViewPager;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
// Here we load the xml layout we created above
setContentView(R.layout.activity_main);
// Set up the action bar.
final ActionBar actionBar = getSupportActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mSectionsPagerAdapter);
// When swiping between different sections, select the corresponding
// tab. We can also use ActionBar.Tab#select() to do this if we have
// a reference to the Tab.
mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener()
{
@Override
public void onPageSelected(int position)
{
actionBar.setSelectedNavigationItem(position);
}
});
// For each of the sections in the app, add a tab to the action bar.
for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++)
{
// Create a tab with text corresponding to the page title defined by
// the adapter. Also specify this Activity object, which implements
// the TabListener interface, as the callback (listener) for when
// this tab is selected.
actionBar.addTab(
actionBar.newTab()
.setText(mSectionsPagerAdapter.getPageTitle(i))
.setTabListener(this));
}
}
@Override
public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction)
{
// When the given tab is selected, switch to the corresponding page in
// the ViewPager.
mViewPager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction)
{
}
@Override
public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction)
{
}
/**
* A {@link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter
{
public SectionsPagerAdapter(FragmentManager fm)
{
super(fm);
}
@Override
public Fragment getItem(int position)
{
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
return new PlaceholderFragment();
}
@Override
public int getCount()
{
// Show 3 total pages.
return 3;
}
@Override
public CharSequence getPageTitle(int position)
{
Locale l = Locale.getDefault();
switch (position)
{
case 0:
return getString(R.string.title_section1).toUpperCase(l);
case 1:
return getString(R.string.title_section2).toUpperCase(l);
case 2:
return getString(R.string.title_section3).toUpperCase(l);
}
return null;
}
}
}
不要忘记在代码中为这些R.string.title_section1, ... 字符串创建字符串,否则会出错。
现在我们必须为片段(将在选项卡内显示的页面)创建一个布局,并且它必须包含一个GridView。
创建一个 fragment_main.xml 布局
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<GridView
android:id="@+id/gridview"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:verticalSpacing="0dp"
android:horizontalSpacing="0dp"
android:stretchMode="columnWidth"
android:numColumns="2" />
</FrameLayout>
现在让我们定义片段类,它将负责扩展此布局并处理视图。
创建一个片段来膨胀 GridView 布局:PlaceHolderFragment.java
/**
* A placeholder fragment containing a the gridview
*/
public class PlaceholderFragment extends Fragment
{
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
// Here we inflate the layout we created above
GridView gridView = (GridView) rootView.findViewById(R.id.gridview);
gridView.setAdapter(new MyAdapter(MainActivity.this.getApplicationContext()));
return rootView;
}
}
现在我们必须创建一个适配器类来处理GridView 的每一项,这样您就可以管理每一项的行为。
创建支持 GridView 项的适配器:MyAdapter.java
正如您在此处看到的,我们将一些项目添加到 GridView,方法是将它们添加到适配器类末尾定义的 Item 类型的 ArrayList。
private class MyAdapter extends BaseAdapter
{
private List<Item> items = new ArrayList<Item>();
private LayoutInflater inflater;
public MyAdapter(Context context)
{
inflater = LayoutInflater.from(context);
items.add(new Item("Image 1", Color.GREEN));
items.add(new Item("Image 2", Color.RED));
items.add(new Item("Image 3", Color.BLUE));
items.add(new Item("Image 4", Color.GRAY));
items.add(new Item("Image 5", Color.YELLOW));
}
@Override
public int getCount() {
return items.size();
}
@Override
public Object getItem(int i)
{
return items.get(i);
}
@Override
public long getItemId(int i)
{
return items.get(i).colorId;
}
@Override
public View getView(int i, View view, ViewGroup viewGroup)
{
View v = view;
ImageView picture;
TextView name;
if(v == null)
{
v = inflater.inflate(R.layout.gridview_item, viewGroup, false);
v.setTag(R.id.picture, v.findViewById(R.id.picture));
v.setTag(R.id.text, v.findViewById(R.id.text));
}
picture = (ImageView)v.getTag(R.id.picture);
name = (TextView)v.getTag(R.id.text);
Item item = (Item)getItem(i);
picture.setBackgroundColor(item.colorId);
name.setText(item.name);
return v;
}
private class Item
{
final String name;
final int colorId;
Item(String name, int drawableId)
{
this.name = name;
this.colorId = drawableId;
}
}
}
现在为了让GridView 项目保持正确的宽度,并排对齐,我们使用自定义类来定义测量尺寸。
为什么需要这样做?根据@kcoppock's answer:
基本上,在 Android 的 ImageView 类中,除非您硬编码宽度和高度,否则无法简单地指定“嘿,保持此视图的正方形纵横比(宽度/高度)”。您可以在适配器的 getView 中对LayoutParams 进行一些手动调整,但坦率地说,让ImageView 处理所有测量结果要简单得多,只需覆盖结果即可说“无论宽度最终是多少,让我的高度保持不变相同”。您永远不必考虑它,它始终是方形的,并且可以按预期工作。基本上这是保持视图正方形的最简单方法。
创建一个类 SquareImageView.java
import android.content.Context;
import android.util.AttributeSet;
import android.widget.ImageView;
public class SquareImageView extends ImageView
{
public SquareImageView(Context context)
{
super(context);
}
public SquareImageView(Context context, AttributeSet attrs)
{
super(context, attrs);
}
public SquareImageView(Context context, AttributeSet attrs, int defStyle)
{
super(context, attrs, defStyle);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
{
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
setMeasuredDimension(getMeasuredWidth(), getMeasuredWidth()); //Snap to width
}
}
现在我们必须为GridView 项定义XML 布局。
创建一个 XML 布局 gridview_item.xml
如您所见,这里我们在布局中添加了两个项目。一个是SquareImageView 类型的元素(我们在上面创建的类)和TextView,它是每个图像的标签。
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.myapp.gridview.SquareImageView
android:id="@+id/picture"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="centerCrop"
/>
<TextView
android:id="@+id/text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingLeft="10dp"
android:paddingRight="10dp"
android:paddingTop="15dp"
android:paddingBottom="15dp"
android:layout_gravity="bottom"
android:textColor="@android:color/white"
android:background="#55000000"
/>
</FrameLayout>
在这里,我测试了代码,这是最终结果。当然,您会更改图像的这些颜色,但这是您应该遵循的方法。
注意:要为GridView 项设置图像而不是颜色,请在MyAdapter 类的getView() 方法中使用setImageResource(int) 而不是setBackgroundColor(int)。