实现Android 抽屉效果

   在Android开发过程中，我们喜欢使用特效，比如抽屉效果，这样可以给人很好的体验。点击一个按钮，就像拉抽屉一样展开界面，这样的效果正是我在这里所要说明的。比如在AVD或真机上，我们都有看过这种效果。比较常用的应用是LAUNCH应用。在这个应用中我们实现了拉抽屉呈现所有的程序，在这里我参考一些别人写的博客试例讲这种实现细节。



创建一个工程。在这里我命名为LauncherDemo.在这个例子中我在main.xml文件中写入如下，贴上代码：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<SlidingDrawer
    android:id="@+id/slidingdrawer"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:handle="@+id/handle"
    android:content="@+id/content">
    <Button
        android:id="@+id/handle"
        android:layout_width="88dip"
        android:layout_height="44dip"
        android:background="@drawable/handle"
        />
    <LinearLayout
        android:id="@+id/content"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:background="#00ff00">
 
       
       <GridView
android:id="@+id/allapps"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
    </LinearLayout>
</SlidingDrawer>
</LinearLayout>

看到这个SlidingDrawer控件。就像使用Button,TextView一样简单使用。



然后在LauncherActivity.java代码如下：
public class LauncherActivity extends Activity implements OnItemClickListener{
private GridView mGridView;
private Context mContext;
private PackageManager mPackageManager;
private List<ResolveInfo> mAllApps;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        setupViews();

    }

    public void setupViews(){
    mContext = LauncherActivity.this;
    mPackageManager = getPackageManager();  //包管理器
    mGridView = (GridView)findViewById(R.id.allapps);
    bindAllApps();

    mGridView.setAdapter(new GridItemAdapter(mContext, mAllApps));
    mGridView.setNumColumns(4);
    mGridView.setOnItemClickListener(this);
    }

    public void bindAllApps(){
    //这里是关键哦，我们平时写的应用总有一个activity申明成这两个属性
    //也就是应用的入口
    Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
        mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);
      
        //符合上面条件的全部查出来,并且排序
        mAllApps = mPackageManager.queryIntentActivities(mainIntent, 0);
        Collections.sort(mAllApps, new ResolveInfo.DisplayNameComparator(mPackageManager));
    }



    //gridview点击事件，点击进入相关应用
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// TODO Auto-generated method stub
ResolveInfo res = mAllApps.get(position);

//该应用的包名和主Activity
String pkg = res.activityInfo.packageName;
String cls = res.activityInfo.name;

ComponentName componet = new ComponentName(pkg, cls);

Intent i = new Intent();
i.setComponent(componet);
startActivity(i);
}

    //不明白BaseAdapter的用法 我高手进阶里有
    private class GridItemAdapter extends BaseAdapter{
    private Context context;
    private List<ResolveInfo> resInfo;

    //构造函数
    public GridItemAdapter(Context c,List<ResolveInfo> res){
    context = c;
    resInfo = res;
    }
@Override
public int getCount() {
// TODO Auto-generated method stub
return resInfo.size();
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return null;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {

//不明白LayoutInflater的我android高手进阶里有
convertView = LayoutInflater.from(context).inflate(R.layout.application_layout, null);

ImageView app_icon = (ImageView)convertView.findViewById(R.id.app_icon);
TextView app_tilte = (TextView)convertView.findViewById(R.id.app_title);

ResolveInfo res = resInfo.get(position);
app_icon.setImageDrawable(res.loadIcon(mPackageManager));
app_tilte.setText(res.loadLabel(mPackageManager).toString());
return convertView;
}

    }
}