Android提高十七篇之多级树形菜单的实现

在Android里要实现树形菜单，都是用ExpandableList(也有高手自己继承ListView或者LinearLayout来做)，但是ExpandableList一般只能实现2级树形菜单......本文也依然使用ExpandableList，但是要实现的是3级树形菜单。本文程序运行效果图：


当用BaseExpandableListAdapter来实现二级树形菜单时，父项(getGroupView())和子项(getChildView())都是使用TextView。当要实现三级树形菜单时，子项(getChildView())就必须使用ExpandableList了.......另外还要定义结构体来方便调用三级树形的数据，二级树形菜单可以用如下：

static public class TreeNode{  
        Object parent;  
        List<Object> childs=new ArrayList<Object>();  
    }

三级树形菜单可以用如下，子项是二级树形菜单的结构体：

static public class SuperTreeNode {  
        Object parent;  
        //二级树形菜单的结构体  
        List<TreeViewAdapter.TreeNode> childs = new ArrayList<TreeViewAdapter.TreeNode>();  
    }

实现三级树形菜单有两点要注意的：
1、第二级也是个树形菜单，因此必须在第二级项目展开/回收时设置足够的空间来完全显示二级树形菜单；
2、在实现三级树形菜单时，发现菜单的方法都是用不了(如OnChildClickListener、OnGroupClickListener等)，因此要获得选中的数据就必须在外部定义好回调函数，然后在第二级生成二级树形菜单时回调这个外部函数。
PS：本文在解决No.2关键点的时候，只能取得第三级选中的序号.....而第一，第二级依然无法获取其序号。
main.xml源码如下：

<?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">  
    <LinearLayout android:id="@+id/LinearLayout01"  
        android:layout_width="wrap_content" android:layout_height="wrap_content">  
        <Button android:layout_height="wrap_content" android:text="两层结构"  
            android:layout_width="160dip" android:id="@+id/btnNormal"></Button>  
        <Button android:layout_height="wrap_content" android:text="三层结构"  
            android:layout_width="160dip" android:id="@+id/btnSuper"></Button>  
    </LinearLayout>  
    <ExpandableListView android:id="@+id/ExpandableListView01"  
        android:layout_width="fill_parent" android:layout_height="fill_parent"></ExpandableListView>  
</LinearLayout>

testExpandableList.java是主类，调用其他工具类，源码如下：

package com.testExpandableList;  
      
      
    import java.util.List;  
    import android.app.Activity;  
    import android.os.Bundle;  
    import android.util.Log;  
    import android.view.View;  
    import android.widget.Button;  
    import android.widget.ExpandableListView;  
    import android.widget.ExpandableListView.OnChildClickListener;  
    import android.widget.Toast;  
      
    public class testExpandableList extends Activity {  
        /** Called when the activity is first created. */  
        ExpandableListView expandableList;  
        TreeViewAdapter adapter;  
        SuperTreeViewAdapter superAdapter;  
        Button btnNormal,btnSuper;  
        // Sample data set.  children[i] contains the children (String[]) for groups[i].  
        public String[] groups = { "xxxx好友", "xxxx同学", "xxxxx女人"};  
        public String[][]  child= {  
                { "A君", "B君", "C君", "D君" },  
                { "同学甲", "同学乙", "同学丙"},  
                { "御姐", "萝莉" }  
        };  
          
        public String[] parent = { "xxxx好友", "xxxx同学"};  
        public String[][][]  child_grandson= {  
                {{"A君"},  
                    {"AA","AAA"}},  
                {{"B君"},  
                    {"BBB","BBBB","BBBBB"}},  
                {{"C君"},  
                    {"CCC","CCCC"}},  
                {{"D君"},  
                    {"DDD","DDDD","DDDDD"}},  
        };  
          
        @Override  
        public void onCreate(Bundle savedInstanceState) {  
            super.onCreate(savedInstanceState);  
            setContentView(R.layout.main);  
            this.setTitle("ExpandableListView练习----hellogv");  
            btnNormal=(Button)this.findViewById(R.id.btnNormal);  
            btnNormal.setOnClickListener(new ClickEvent());  
            btnSuper=(Button)this.findViewById(R.id.btnSuper);  
            btnSuper.setOnClickListener(new ClickEvent());  
            adapter=new TreeViewAdapter(this,TreeViewAdapter.PaddingLeft>>1);  
            superAdapter=new SuperTreeViewAdapter(this,stvClickEvent);  
            expandableList=(ExpandableListView) testExpandableList.this.findViewById(R.id.ExpandableListView01);  
        }  
          
        class ClickEvent implements View.OnClickListener{  
      
            @Override  
            public void onClick(View v) {  
                adapter.RemoveAll();  
                adapter.notifyDataSetChanged();  
                superAdapter.RemoveAll();  
                superAdapter.notifyDataSetChanged();  
                  
                if(v==btnNormal)  
                {  
                    List<TreeViewAdapter.TreeNode> treeNode = adapter.GetTreeNode();  
                    for(int i=0;i<groups.length;i++)  
                    {  
                        TreeViewAdapter.TreeNode node=new TreeViewAdapter.TreeNode();  
                        node.parent=groups[i];  
                        for(int ii=0;ii<child[i].length;ii++)  
                        {  
                            node.childs.add(child[i][ii]);  
                        }  
                        treeNode.add(node);  
                    }  
                      
                    adapter.UpdateTreeNode(treeNode);       
                    expandableList.setAdapter(adapter);  
                    expandableList.setOnChildClickListener(new OnChildClickListener(){  
      
                        @Override  
                        public boolean onChildClick(ExpandableListView arg0, View arg1,  
                                int parent, int children, long arg4) {  
                              
                            String str="parent id:"+String.valueOf(parent)+",children id:"+String.valueOf(children);  
                            Toast.makeText(testExpandableList.this, str, 300).show();  
                            return false;  
                        }  
                    });  
                }  
                else if(v==btnSuper){  
                    List<SuperTreeViewAdapter.SuperTreeNode> superTreeNode = superAdapter.GetTreeNode();  
                    for(int i=0;i<parent.length;i++)//第一层  
                    {  
                        SuperTreeViewAdapter.SuperTreeNode superNode=new SuperTreeViewAdapter.SuperTreeNode();  
                        superNode.parent=parent[i];  
                          
                        //第二层  
                        for(int ii=0;ii<child_grandson.length;ii++)  
                        {  
                            TreeViewAdapter.TreeNode node=new TreeViewAdapter.TreeNode();  
                            node.parent=child_grandson[ii][0][0];//第二级菜单的标题  
                              
                            for(int iii=0;iii<child_grandson[ii][1].length;iii++)//第三级菜单  
                            {  
                                node.childs.add(child_grandson[ii][1][iii]);  
                            }  
                            superNode.childs.add(node);  
                        }  
                        superTreeNode.add(superNode);  
                          
                    }  
                    superAdapter.UpdateTreeNode(superTreeNode);  
                    expandableList.setAdapter(superAdapter);  
                }  
            }  
        }  
      
        /** 
         * 三级树形菜单的事件不再可用，本函数由三级树形菜单的子项（二级菜单）进行回调 
         */  
        OnChildClickListener stvClickEvent=new OnChildClickListener(){  
      
            @Override  
            public boolean onChildClick(ExpandableListView parent,  
                    View v, int groupPosition, int childPosition,  
                    long id) {  
                String str="parent id:"+String.valueOf(groupPosition)+",children id:"+String.valueOf(childPosition);  
                Toast.makeText(testExpandableList.this, str, 300).show();  
                  
                return false;  
            }  
              
        };  
    }

TreeViewAdapter.java是实现二级树形菜单的工具类，源码如下：

package com.testExpandableList;  
      
    import java.util.ArrayList;  
    import java.util.List;  
    import android.content.Context;  
    import android.util.Log;  
    import android.view.Gravity;  
    import android.view.View;  
    import android.view.ViewGroup;  
    import android.widget.AbsListView;  
    import android.widget.BaseExpandableListAdapter;  
    import android.widget.TextView;  
      
      
    public class TreeViewAdapter extends BaseExpandableListAdapter{  
        public static final int ItemHeight=48;//每项的高度  
        public static final int PaddingLeft=36;//每项的高度  
        private int myPaddingLeft=0;//如果是由SuperTreeView调用，则作为子项需要往右移  
      
        static public class TreeNode{  
            Object parent;  
            List<Object> childs=new ArrayList<Object>();  
        }  
          
        List<TreeNode> treeNodes = new ArrayList<TreeNode>();  
        Context parentContext;  
          
        public TreeViewAdapter(Context view,int myPaddingLeft)  
        {  
            parentContext=view;  
            this.myPaddingLeft=myPaddingLeft;  
        }  
          
        public List<TreeNode> GetTreeNode()  
        {  
            return treeNodes;  
        }  
          
        public void UpdateTreeNode(List<TreeNode> nodes)  
        {  
            treeNodes=nodes;  
        }  
          
        public void RemoveAll()  
        {  
            treeNodes.clear();  
        }  
          
        public Object getChild(int groupPosition, int childPosition) {  
            return treeNodes.get(groupPosition).childs.get(childPosition);  
        }  
      
        public int getChildrenCount(int groupPosition) {  
            return treeNodes.get(groupPosition).childs.size();  
        }  
      
        static public TextView getTextView(Context context) {  
            AbsListView.LayoutParams lp = new AbsListView.LayoutParams(  
                    ViewGroup.LayoutParams.FILL_PARENT, ItemHeight);  
      
            TextView textView = new TextView(context);  
            textView.setLayoutParams(lp);  
            textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);  
            return textView;  
        }  
      
        public View getChildView(int groupPosition, int childPosition,  
                boolean isLastChild, View convertView, ViewGroup parent) {  
            TextView textView = getTextView(this.parentContext);  
            textView.setText(getChild(groupPosition, childPosition).toString());  
            textView.setPadding(myPaddingLeft+PaddingLeft, 0, 0, 0);  
            return textView;  
        }  
      
        public View getGroupView(int groupPosition, boolean isExpanded,  
                View convertView, ViewGroup parent) {  
            TextView textView = getTextView(this.parentContext);  
            textView.setText(getGroup(groupPosition).toString());  
            textView.setPadding(myPaddingLeft+(PaddingLeft>>1), 0, 0, 0);  
            return textView;  
        }  
      
        public long getChildId(int groupPosition, int childPosition) {  
            return childPosition;  
        }  
      
        public Object getGroup(int groupPosition) {  
            return treeNodes.get(groupPosition).parent;  
        }  
      
        public int getGroupCount() {  
            return treeNodes.size();  
        }  
      
        public long getGroupId(int groupPosition) {  
            return groupPosition;  
        }  
      
        public boolean isChildSelectable(int groupPosition, int childPosition) {  
            return true;  
        }  
      
        public boolean hasStableIds() {  
            return true;  
        }  
    }

SuperTreeViewAdapter.java是实现三级树形菜单的工具类，会用到TreeViewAdapter.java，源码如下：

package com.testExpandableList;  
      
    import java.util.ArrayList;  
    import java.util.List;  
    import com.testExpandableList.TreeViewAdapter.TreeNode;  
    import android.content.Context;  
    import android.view.View;  
    import android.view.ViewGroup;  
    import android.widget.AbsListView;  
    import android.widget.BaseExpandableListAdapter;  
    import android.widget.ExpandableListView;  
    import android.widget.ExpandableListView.OnChildClickListener;  
    import android.widget.ExpandableListView.OnGroupCollapseListener;  
    import android.widget.ExpandableListView.OnGroupExpandListener;  
    import android.widget.TextView;  
      
    public class SuperTreeViewAdapter extends BaseExpandableListAdapter {  
      
        static public class SuperTreeNode {  
            Object parent;  
            //二级树形菜单的结构体  
            List<TreeViewAdapter.TreeNode> childs = new ArrayList<TreeViewAdapter.TreeNode>();  
        }  
      
        private List<SuperTreeNode> superTreeNodes = new ArrayList<SuperTreeNode>();  
        private Context parentContext;  
        private OnChildClickListener stvClickEvent;//外部回调函数  
          
        public SuperTreeViewAdapter(Context view,OnChildClickListener stvClickEvent) {  
            parentContext = view;  
            this.stvClickEvent=stvClickEvent;  
        }  
      
        public List<SuperTreeNode> GetTreeNode() {  
            return superTreeNodes;  
        }  
      
        public void UpdateTreeNode(List<SuperTreeNode> node) {  
            superTreeNodes = node;  
        }  
          
        public void RemoveAll()  
        {  
            superTreeNodes.clear();  
        }  
          
        public Object getChild(int groupPosition, int childPosition) {  
            return superTreeNodes.get(groupPosition).childs.get(childPosition);  
        }  
      
        public int getChildrenCount(int groupPosition) {  
            return superTreeNodes.get(groupPosition).childs.size();  
        }  
      
        public ExpandableListView getExpandableListView() {  
            AbsListView.LayoutParams lp = new AbsListView.LayoutParams(  
                    ViewGroup.LayoutParams.FILL_PARENT, TreeViewAdapter.ItemHeight);  
            ExpandableListView superTreeView = new ExpandableListView(parentContext);  
            superTreeView.setLayoutParams(lp);  
            return superTreeView;  
        }  
      
        /** 
         * 三层树结构中的第二层是一个ExpandableListView 
         */   
        public View getChildView(int groupPosition, int childPosition,  
                boolean isLastChild, View convertView, ViewGroup parent) {  
            // 是   
            final ExpandableListView treeView = getExpandableListView();  
            final TreeViewAdapter treeViewAdapter = new TreeViewAdapter(this.parentContext,0);  
            List<TreeNode> tmp = treeViewAdapter.GetTreeNode();//临时变量取得TreeViewAdapter的TreeNode集合，可为空  
            final TreeNode treeNode=(TreeNode) getChild(groupPosition, childPosition);  
            tmp.add(treeNode);  
            treeViewAdapter.UpdateTreeNode(tmp);  
            treeView.setAdapter(treeViewAdapter);  
              
            //关键点：取得选中的二级树形菜单的父子节点,结果返回给外部回调函数  
            treeView.setOnChildClickListener(this.stvClickEvent);  
              
            /** 
             * 关键点：第二级菜单展开时通过取得节点数来设置第三级菜单的大小 
             */  
            treeView.setOnGroupExpandListener(new OnGroupExpandListener() {  
                @Override  
                public void onGroupExpand(int groupPosition) {  
                      
                    AbsListView.LayoutParams lp = new AbsListView.LayoutParams(  
                            ViewGroup.LayoutParams.FILL_PARENT,  
                            (treeNode.childs.size()+1)*TreeViewAdapter.ItemHeight + 10);  
                    treeView.setLayoutParams(lp);  
                }  
            });  
              
            /** 
             * 第二级菜单回收时设置为标准Item大小 
             */  
            treeView.setOnGroupCollapseListener(new OnGroupCollapseListener() {  
                @Override  
                public void onGroupCollapse(int groupPosition) {  
                      
                    AbsListView.LayoutParams lp = new AbsListView.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,  
                            TreeViewAdapter.ItemHeight);  
                    treeView.setLayoutParams(lp);  
                }  
            });  
            treeView.setPadding(TreeViewAdapter.PaddingLeft, 0, 0, 0);  
            return treeView;  
        }  
      
        /** 
         * 三级树结构中的首层是TextView,用于作为title 
         */  
        public View getGroupView(int groupPosition, boolean isExpanded,  
                View convertView, ViewGroup parent) {  
            TextView textView = TreeViewAdapter.getTextView(this.parentContext);  
            textView.setText(getGroup(groupPosition).toString());  
            textView.setPadding(TreeViewAdapter.PaddingLeft, 0, 0, 0);  
            return textView;  
        }  
      
        public long getChildId(int groupPosition, int childPosition) {  
            return childPosition;  
        }  
      
        public Object getGroup(int groupPosition) {  
            return superTreeNodes.get(groupPosition).parent;  
        }  
      
        public int getGroupCount() {  
            return superTreeNodes.size();  
        }  
      
        public long getGroupId(int groupPosition) {  
            return groupPosition;  
        }  
      
        public boolean isChildSelectable(int groupPosition, int childPosition) {  
            return true;  
        }  
      
        public boolean hasStableIds() {  
            return true;  
        }  
    }

总结，使用ExpandableList实现三级树形菜单时有些bug不好解决，而且定义三维数组的时候也要倍加小心......所以尽量把数据化简来使用二级树形菜单。