Android提高21篇之十七：多級樹形菜單的實現

       在Android裡要實現樹形菜單，都是用ExpandableList(也有高手自己繼承ListView或者LinearLayout來做)，但是ExpandableList一般只能實現2級樹形菜單......本文也依然使用ExpandableList，但是要實現的是3級樹形菜單。本文程序運行效果圖：

       當用BaseExpandableListAdapter來實現二級樹形菜單時，父項(getGroupView())和子項(getChildView())都是使用TextView。當要實現三級樹形菜單時，子項(getChildView())就必須使用ExpandableList了.......另外還要定義結構體來方便調用三級樹形的數據，二級樹形菜單可以用如下：

1. static public class TreeNode{  
2.                Object parent;  
3.                List childs=new ArrayList();  
4.        }  

       三級樹形菜單可以用如下，子項是二級樹形菜單的結構體：

1. static public class SuperTreeNode {  
2.                Object parent;  
3.                //二級樹形菜單的結構體  
4.                List[tr] childs = new ArrayList[tr]();  
5.        }  

       實現三級樹形菜單有兩點要注意的：1、第二級也是個樹形菜單，因此必須在第二級項目展開/回收時設置足夠的空間來完全顯示二級樹形菜單；2、在實現三級樹形菜單時，發現菜單的方法都是用不了(如OnChildClickListener、OnGroupClickListener等)，因此要獲得選中的數據就必須在外部定義好回調函數，然後在第二級生成二級樹形菜單時回調這個外部函數。PS：本文在解決No.2關鍵點的時候，只能取得第三級選中的序號.....而第一，第二級依然無法獲取其序號。main.xml源碼如下：

1. <linearlayout xmlns:android="http://schemas.android.com/apk/res/android"   
2.         android:orientation="vertical" android:layout_width="fill_parent"  
3.         android:layout_height="fill_parent">  
4.         <linearlayout android:id="@+id/LinearLayout01"   
5.                 android:layout_width="wrap_content" android:layout_height="wrap_content">  
6.                 <button android:layout_height="wrap_content" android:text="兩層結構"   
7.                         android:layout_width="160dip" android:id="@+id/btnNormal">  
8.                 <button android:layout_height="wrap_content" android:text="三層結構"   
9.                         android:layout_width="160dip" android:id="@+id/btnSuper">  
10.           
11.         <expandablelistview android:id="@+id/ExpandableListView01"   
12.                 android:layout_width="fill_parent" android:layout_height="fill_parent">  

        testExpandableList.java是主類，調用其他工具類，源碼如下：

1. package com.testExpandableList;  
2.   
3.   
4. import java.util.List;  
5. import android.app.Activity;  
6. import android.os.Bundle;  
7. import android.util.Log;  
8. import android.view.View;  
9. import android.widget.Button;  
10. import android.widget.ExpandableListView;  
11. import android.widget.ExpandableListView.OnChildClickListener;  
12. import android.widget.Toast;  
13.   
14. public class testExpandableList extends Activity {  
15.     /** Called when the activity is first created. */  
16.         ExpandableListView expandableList;  
17.         TreeViewAdapter adapter;  
18.         SuperTreeViewAdapter superAdapter;  
19.         Button btnNormal,btnSuper;  
20.     // Sample data set.  children[i] contains the children (String[]) for groups[i].  
21.     public String[] groups = { "xxxx好友", "xxxx同學", "xxxxx女人"};  
22.     public String[][]  child= {  
23.             { "A君", "B君", "C君", "D君" },  
24.             { "同學甲", "同學乙", "同學丙"},  
25.             { "御姐", "蘿莉" }  
26.     };  
27.       
28.     public String[] parent = { "xxxx好友", "xxxx同學"};  
29.     public String[][][]  child_grandson= {  
30.                     {{"A君"},  
31.                             {"AA","AAA"}},  
32.                     {{"B君"},  
33.                             {"BBB","BBBB","BBBBB"}},  
34.                     {{"C君"},  
35.                             {"CCC","CCCC"}},  
36.                     {{"D君"},  
37.                             {"DDD","DDDD","DDDDD"}},  
38.     };  
39.       
40.     @Override  
41.     public void onCreate(Bundle savedInstanceState) {  
42.         super.onCreate(savedInstanceState);  
43.         setContentView(R.layout.main);  
44.         this.setTitle("ExpandableListView練習----hellogv");  
45.         btnNormal=(Button)this.findViewById(R.id.btnNormal);  
46.         btnNormal.setOnClickListener(new ClickEvent());  
47.         btnSuper=(Button)this.findViewById(R.id.btnSuper);  
48.         btnSuper.setOnClickListener(new ClickEvent());  
49.         adapter=new TreeViewAdapter(this,TreeViewAdapter.PaddingLeft>>1);  
50.         superAdapter=new SuperTreeViewAdapter(this,stvClickEvent);  
51.         expandableList=(ExpandableListView) testExpandableList.this.findViewById(R.id.ExpandableListView01);  
52.     }  
53.       
54.     class ClickEvent implements View.OnClickListener{  
55.   
56.                 @Override  
57.                 public void onClick(View v) {  
58.                         adapter.RemoveAll();  
59.                         adapter.notifyDataSetChanged();  
60.                         superAdapter.RemoveAll();  
61.                         superAdapter.notifyDataSetChanged();  
62.                           
63.                         if(v==btnNormal)  
64.                         {  
65.                         List[tr] treeNode = adapter.GetTreeNode();  
66.                         for(int i=0;i<groups.length;i++)  
67.                         {  
68.                                 TreeViewAdapter.TreeNode node=new TreeViewAdapter.TreeNode();  
69.                                 node.parent=groups[i];  
70.                                 for(int ii=0;ii<child[i].length;ii++)  
71.                                 {  
72.                                         node.childs.add(child[i][ii]);  
73.                                 }  
74.                                 treeNode.add(node);  
75.                         }  
76.                           
77.                         adapter.UpdateTreeNode(treeNode);       
78.                         expandableList.setAdapter(adapter);  
79.                         expandableList.setOnChildClickListener(new OnChildClickListener(){  
80.   
81.                                         @Override  
82.                                         public boolean onChildClick(ExpandableListView arg0, View arg1,  
83.                                                         int parent, int children, long arg4) {  
84.                                                   
85.                                                 String str="parent id:"+String.valueOf(parent)+",children id:"+String.valueOf(children);  
86.                                                 Toast.makeText(testExpandableList.this, str, 300).show();  
87.                                                 return false;  
88.                                         }  
89.                         });  
90.                         }  
91.                         else if(v==btnSuper){  
92.                                 List superTreeNode = superAdapter.GetTreeNode();  
93.                         for(int i=0;i<parent.length;i++) 第一層  
94.                         {  
95.                                 SuperTreeViewAdapter.SuperTreeNode superNode=new SuperTreeViewAdapter.SuperTreeNode();  
96.                                 superNode.parent=parent[i];  
97.                                   
98.                                 //第二層  
99.                                 for(int ii=0;ii<child_grandson.length;ii++)  
100.                             {  
101.                                     TreeViewAdapter.TreeNode node=new TreeViewAdapter.TreeNode();  
102.                                     node.parent=child_grandson[ii][0][0];//第二級菜單的標題  
103.                                       
104.                                     for(int iii=0;iii<child_grandson[ii][1].length;iii++) 第三級菜單  
105.                                     {  
106.                                             node.childs.add(child_grandson[ii][1][iii]);  
107.                                     }  
108.                                     superNode.childs.add(node);  
109.                             }  
110.                                 superTreeNode.add(superNode);  
111.                                   
112.                         }  
113.                         superAdapter.UpdateTreeNode(superTreeNode);  
114.                         expandableList.setAdapter(superAdapter);  
115.                         }  
116.                 }  
117.     }  
118.   
119.     /** 
120.      * 三級樹形菜單的事件不再可用，本函數由三級樹形菜單的子項（二級菜單）進行回調 
121.      */  
122.     OnChildClickListener stvClickEvent=new OnChildClickListener(){  
123.   
124.                 @Override  
125.                 public boolean onChildClick(ExpandableListView parent,  
126.                                 View v, int groupPosition, int childPosition,  
127.                                 long id) {  
128.                         String str="parent id:"+String.valueOf(groupPosition)+",children id:"+String.valueOf(childPosition);  
129.                         Toast.makeText(testExpandableList.this, str, 300).show();  
130.                           
131.                         return false;  
132.                 }  
133.               
134.     };  
135. }  

       TreeViewAdapter.java是實現二級樹形菜單的工具類，源碼如下：

1. package com.testExpandableList;  
2.   
3. import java.util.ArrayList;  
4. import java.util.List;  
5. import android.content.Context;  
6. import android.util.Log;  
7. import android.view.Gravity;  
8. import android.view.View;  
9. import android.view.ViewGroup;  
10. import android.widget.AbsListView;  
11. import android.widget.BaseExpandableListAdapter;  
12. import android.widget.TextView;  
13.   
14.   
15. public class TreeViewAdapter extends BaseExpandableListAdapter{  
16.         public static final int ItemHeight=48;//每項的高度  
17.         public static final int PaddingLeft=36;//每項的高度  
18.         private int myPaddingLeft=0;//如果是由SuperTreeView調用，則作為子項需要往右移  
19.   
20.         static public class TreeNode{  
21.                 Object parent;  
22.                 List childs=new ArrayList();  
23.         }  
24.           
25.         List[tr] treeNodes = new ArrayList[tr]();  
26.         Context parentContext;  
27.           
28.         public TreeViewAdapter(Context view,int myPaddingLeft)  
29.         {  
30.                 parentContext=view;  
31.                 this.myPaddingLeft=myPaddingLeft;  
32.         }  
33.           
34.         public List[tr] GetTreeNode()  
35.         {  
36.                 return treeNodes;  
37.         }  
38.           
39.         public void UpdateTreeNode(List[tr] nodes)  
40.         {  
41.                 treeNodes=nodes;  
42.         }  
43.           
44.         public void RemoveAll()  
45.         {  
46.                 treeNodes.clear();  
47.         }  
48.           
49.         public Object getChild(int groupPosition, int childPosition) {  
50.                 return treeNodes.get(groupPosition).childs.get(childPosition);  
51.         }  
52.   
53.         public int getChildrenCount(int groupPosition) {  
54.                 return treeNodes.get(groupPosition).childs.size();  
55.         }  
56.   
57.         static public TextView getTextView(Context context) {  
58.                 AbsListView.LayoutParams lp = new AbsListView.LayoutParams(  
59.                                 ViewGroup.LayoutParams.FILL_PARENT, ItemHeight);  
60.   
61.                 TextView textView = new TextView(context);  
62.                 textView.setLayoutParams(lp);  
63.                 textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);  
64.                 return textView;  
65.         }  
66.   
67.         public View getChildView(int groupPosition, int childPosition,  
68.                         boolean isLastChild, View convertView, ViewGroup parent) {  
69.                 TextView textView = getTextView(this.parentContext);  
70.                 textView.setText(getChild(groupPosition, childPosition).toString());  
71.                 textView.setPadding(myPaddingLeft+PaddingLeft, 0, 0, 0);  
72.                 return textView;  
73.         }  
74.   
75.         public View getGroupView(int groupPosition, boolean isExpanded,  
76.                         View convertView, ViewGroup parent) {  
77.                 TextView textView = getTextView(this.parentContext);  
78.                 textView.setText(getGroup(groupPosition).toString());  
79.                 textView.setPadding(myPaddingLeft+(PaddingLeft>>1), 0, 0, 0);  
80.                 return textView;  
81.         }  
82.   
83.         public long getChildId(int groupPosition, int childPosition) {  
84.                 return childPosition;  
85.         }  
86.   
87.         public Object getGroup(int groupPosition) {  
88.                 return treeNodes.get(groupPosition).parent;  
89.         }  
90.   
91.         public int getGroupCount() {  
92.                 return treeNodes.size();  
93.         }  
94.   
95.         public long getGroupId(int groupPosition) {  
96.                 return groupPosition;  
97.         }  
98.   
99.         public boolean isChildSelectable(int groupPosition, int childPosition) {  
100.                 return true;  
101.         }  
102.   
103.         public boolean hasStableIds() {  
104.                 return true;  
105.         }  
106. }  

        SuperTreeViewAdapter.java是實現三級樹形菜單的工具類，會用到TreeViewAdapter.java，源碼如下：

1. package com.testExpandableList;  
2.   
3. import java.util.ArrayList;  
4. import java.util.List;  
5. import com.testExpandableList.TreeViewAdapter.TreeNode;  
6. import android.content.Context;  
7. import android.view.View;  
8. import android.view.ViewGroup;  
9. import android.widget.AbsListView;  
10. import android.widget.BaseExpandableListAdapter;  
11. import android.widget.ExpandableListView;  
12. import android.widget.ExpandableListView.OnChildClickListener;  
13. import android.widget.ExpandableListView.OnGroupCollapseListener;  
14. import android.widget.ExpandableListView.OnGroupExpandListener;  
15. import android.widget.TextView;  
16.   
17. public class SuperTreeViewAdapter extends BaseExpandableListAdapter {  
18.   
19.         static public class SuperTreeNode {  
20.                 Object parent;  
21.                 //二級樹形菜單的結構體  
22.                 List[tr] childs = new ArrayList[tr]();  
23.         }  
24.   
25.         private List superTreeNodes = new ArrayList();  
26.         private Context parentContext;  
27.         private OnChildClickListener stvClickEvent;//外部回調函數  
28.           
29.         public SuperTreeViewAdapter(Context view,OnChildClickListener stvClickEvent) {  
30.                 parentContext = view;  
31.                 this.stvClickEvent=stvClickEvent;  
32.         }  
33.   
34.         public List GetTreeNode() {  
35.                 return superTreeNodes;  
36.         }  
37.   
38.         public void UpdateTreeNode(List node) {  
39.                 superTreeNodes = node;  
40.         }  
41.           
42.         public void RemoveAll()  
43.         {  
44.                 superTreeNodes.clear();  
45.         }  
46.           
47.         public Object getChild(int groupPosition, int childPosition) {  
48.                 return superTreeNodes.get(groupPosition).childs.get(childPosition);  
49.         }  
50.   
51.         public int getChildrenCount(int groupPosition) {  
52.                 return superTreeNodes.get(groupPosition).childs.size();  
53.         }  
54.   
55.         public ExpandableListView getExpandableListView() {  
56.                 AbsListView.LayoutParams lp = new AbsListView.LayoutParams(  
57.                                 ViewGroup.LayoutParams.FILL_PARENT, TreeViewAdapter.ItemHeight);  
58.                 ExpandableListView superTreeView = new ExpandableListView(parentContext);  
59.                 superTreeView.setLayoutParams(lp);  
60.                 return superTreeView;  
61.         }  
62.   
63.         /** 
64.          * 三層樹結構中的第二層是一個ExpandableListView 
65.          */          
66.         public View getChildView(int groupPosition, int childPosition,  
67.                         boolean isLastChild, View convertView, ViewGroup parent) {  
68.                 // 是   
69.                 final ExpandableListView treeView = getExpandableListView();  
70.                 final TreeViewAdapter treeViewAdapter = new TreeViewAdapter(this.parentContext,0);  
71.                 List[tr] tmp = treeViewAdapter.GetTreeNode();//臨時變量取得TreeViewAdapter的TreeNode集合，可為空  
72.                 final TreeNode treeNode=(TreeNode) getChild(groupPosition, childPosition);  
73.                 tmp.add(treeNode);  
74.                 treeViewAdapter.UpdateTreeNode(tmp);  
75.                 treeView.setAdapter(treeViewAdapter);  
76.                   
77.                 //關鍵點：取得選中的二級樹形菜單的父子節點,結果返回給外部回調函數  
78.                 treeView.setOnChildClickListener(this.stvClickEvent);  
79.                   
80.                 /** 
81.                  * 關鍵點：第二級菜單展開時通過取得節點數來設置第三級菜單的大小 
82.                  */  
83.                 treeView.setOnGroupExpandListener(new OnGroupExpandListener() {  
84.                         @Override  
85.                         public void onGroupExpand(int groupPosition) {  
86.                                   
87.                                 AbsListView.LayoutParams lp = new AbsListView.LayoutParams(  
88.                                                 ViewGroup.LayoutParams.FILL_PARENT,  
89.                                                 (treeNode.childs.size()+1)*TreeViewAdapter.ItemHeight + 10);  
90.                                 treeView.setLayoutParams(lp);  
91.                         }  
92.                 });  
93.                   
94.                 /** 
95.                  * 第二級菜單回收時設置為標准Item大小 
96.                  */  
97.                 treeView.setOnGroupCollapseListener(new OnGroupCollapseListener() {  
98.                         @Override  
99.                         public void onGroupCollapse(int groupPosition) {  
100.                                   
101.                                 AbsListView.LayoutParams lp = new AbsListView.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,  
102.                                                 TreeViewAdapter.ItemHeight);  
103.                                 treeView.setLayoutParams(lp);  
104.                         }  
105.                 });  
106.                 treeView.setPadding(TreeViewAdapter.PaddingLeft, 0, 0, 0);  
107.                 return treeView;  
108.         }  
109.   
110.         /** 
111.          * 三級樹結構中的首層是TextView,用於作為title 
112.          */  
113.         public View getGroupView(int groupPosition, boolean isExpanded,  
114.                         View convertView, ViewGroup parent) {  
115.                 TextView textView = TreeViewAdapter.getTextView(this.parentContext);  
116.                 textView.setText(getGroup(groupPosition).toString());  
117.                 textView.setPadding(TreeViewAdapter.PaddingLeft, 0, 0, 0);  
118.                 return textView;  
119.         }  
120.   
121.         public long getChildId(int groupPosition, int childPosition) {  
122.                 return childPosition;  
123.         }  
124.   
125.         public Object getGroup(int groupPosition) {  
126.                 return superTreeNodes.get(groupPosition).parent;  
127.         }  
128.   
129.         public int getGroupCount() {  
130.                 return superTreeNodes.size();  
131.         }  
132.   
133.         public long getGroupId(int groupPosition) {  
134.                 return groupPosition;  
135.         }  
136.   
137.         public boolean isChildSelectable(int groupPosition, int childPosition) {  
138.                 return true;  
139.         }  
140.   
141.         public boolean hasStableIds() {  
142.                 return true;  
143.         }  
144. }  

       總結，使用ExpandableList實現三級樹形菜單時有些bug不好解決，而且定義三維數組的時候也要倍加小心......所以盡量把數據化簡來使用二級樹形菜單。