Android开发实践：多级列表的封装与应用
Android中多级列表可以使用ExpandableListView和SimpleExpandableListAdapter配合来实现，但是，SimpleExpandableListAdapter用起来挺麻烦的，不易理解，而且扩展性也不好，因此，自定义BaseExpandableListAdapter类的子类以及封装相关的操作，用起来会更加直观和方便，我把我设计的封装贴出来供新手参考吧。 首先上效果图，如图所示： 1. 首先设计多级列表的标题类 就像文件和文件夹可以统一地用File类来抽象一样，多级列表的一级标题和二级标题其实也可以用同一个基类来抽象，因此，我设计了一个基类和两个子类，GroupList，GroupListChild 和 GroupListParent，其实现如下所示： （1） GroupList 多级列表标题的抽象基类 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 public abstract class GroupList{ private final StringmTitle; public GroupList(Stringtitle){ mTitle=title; } public StringgetTitle(){ return mTitle; } public abstract List<GroupList>getChild(); public abstract int getResource(); public abstract void buildView(Viewv); } （2） GroupListChild 多级列表二级标题子类 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 public class GroupListChild extends GroupList{ public GroupListChild(Stringtitle){ super (title); } @Override public int getResource(){ return R.layout.grouplist_child; } @Override public List<GroupList>getChild(){ return null ; } @Override public void buildView(Viewv){ TextViewtextView=(TextView)v.findViewById(R.id.GroupListChild); textView.setText(getTitle()); } } （3） GroupListParent 多级列表一级标题子类 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 public class GroupListParent extends GroupList{ private List<GroupList>mPopListChilds; public GroupListParent(Stringtitle,List<GroupList>childs){ super (title); mPopListChilds=childs; } @Override public int getResource(){ return R.layout.grouplist_parent; } @Override public List<GroupList>getChild(){ return mPopListChilds; } @Override public void buildView(Viewv){ TextViewtextView=(TextView)v.findViewById(R.id.GroupListParent); textView.setText(getTitle()); } } 2. 设计BaseExpandableListAdapter的子类 我设计的子类是一种通用的Adapter子类，类的实现中并不包含具体的Layout实现，所有的Layout都由GroupList的getResource和buildView来负责，因此，可以非常灵活地修改Layout的具体实现，而不用修改Adapter的代码。 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 public class GroupListAdapter extends BaseExpandableListAdapter{ private ContextmContext; private List<GroupList>mGroups; public GroupListAdapter(Contextcontext,List<GroupList>groups){ this .mContext=context; this .mGroups=groups; } @Override public ObjectgetChild( int groupPosition, int childPosition){ List<GroupList>chList=mGroups.get(groupPosition).getChild(); if (chList== null ){ return null ; } return chList.get(childPosition); } @Override public long getChildId( int groupPosition, int childPosition){ return childPosition; } @Override public ViewgetChildView( int groupPosition, int childPosition, boolean isLastChild,Viewview,ViewGroupparent){ GroupListchild=(GroupList)getChild(groupPosition,childPosition); if (child== null ){ return null ; } if (view== null ){ LayoutInflaterinflater=(LayoutInflater)mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE); view=(RelativeLayout)inflater.inflate(child.getResource(), null ); } child.buildView(view); return view; } @Override public int getChildrenCount( int groupPosition){ List<GroupList>chList=mGroups.get(groupPosition).getChild(); if (chList== null ){ return 0 ; } return chList.size(); } @Override public ObjectgetGroup( int groupPosition){ return mGroups.get(groupPosition); } @Override public int getGroupCount(){ return mGroups.size(); } @Override public long getGroupId( int groupPosition){ return groupPosition; } @Override public ViewgetGroupView( int groupPosition, boolean isLastChild,Viewview,ViewGroupparent){ GroupListgroup=(GroupList)getGroup(groupPosition); if (view== null ){ LayoutInflaterinflater=(LayoutInflater)mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE); view=(RelativeLayout)inflater.inflate(group.getResource(), null ); } group.buildView(view); return view; } @Override public boolean hasStableIds(){ return true ; } @Override public boolean isChildSelectable( int arg0, int arg1){ return true ; } } 3. 应用代码 为了简化，我就直接在MainActivity中使用上述封装的类来完成多级列表的功能演示，示例如下： 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 public class MainActivity extends Activity implements OnGroupClickListener,OnChildClickListener{ private ExpandableListViewmlistView; private GroupListAdaptermAdapter; private static final String[]mParentMenu={ "Book" , "Video" , "Audio" }; private static final String[][]mChildMenu={ { "book1" , "book2" , "book3" , "book4" }, { "video1" , "video2" }, { "audio1" , "audio2" , "audio3" , "audio4" } }; @Override protected void onCreate(BundlesavedInstanceState){ super .onCreate(savedInstanceState); mlistView= new ExpandableListView( this ); mlistView.setOnGroupClickListener( this ); mlistView.setOnChildClickListener( this ); List<GroupList>groups= new ArrayList<GroupList>(); for ( int i= 0 ;i<mParentMenu.length;i++){ List<GroupList>childs= new ArrayList<GroupList>(); for ( int j= 0 ;j<mChildMenu[i].length;j++){ childs.add( new GroupListChild(mChildMenu[i][j])); } groups.add( new GroupListParent(mParentMenu[i],childs)); } mAdapter= new GroupListAdapter( this ,groups); mlistView.setAdapter(mAdapter); setContentView(mlistView); } @Override public boolean onChildClick(ExpandableListViewparent,Viewv, int groupPosition, int childPosition, long id){ return false ; } @Override public boolean onGroupClick(ExpandableListViewparent,Viewv, int groupPosition, long id){ return false ; } } 4. 相关的xml文件 （1） grouplist_child.xml 文件 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 <? xml version = "1.0" encoding = "utf-8" ?> < RelativeLayout xmlns:android = "http://schemas.android.com/apk/res/android" android:layout_width = "match_parent" android:layout_height = "match_parent" android:orientation = "horizontal" > < TextView android:id = "@+id/GroupListChild" android:layout_width = "wrap_content" android:layout_height = "wrap_content" android:textColor = "#FFFF0000" android:layout_margin = "10dp" android:layout_centerInParent = "true" /> </ RelativeLayout > （2） grouplist_parent.xml 文件 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 <? xml version = "1.0" encoding = "utf-8" ?> < RelativeLayout xmlns:android = "http://schemas.android.com/apk/res/android" android:layout_width = "match_parent" android:layout_height = "match_parent" android:orientation = "horizontal" > < TextView android:id = "@+id/GroupListParent" android:layout_width = "wrap_content" android:layout_height = "wrap_content" android:textColor = "@android:color/black" android:textStyle = "bold" android:layout_margin = "10dp" android:layout_centerInParent = "true" /> </ RelativeLayout > 本文转自 Jhuster 51CTO博客，原文链接：http://blog.51cto.com/ticktick/1289642，如需转载请自行联系原作者
