Android提高之多级树形菜单的实现方法

一般来说在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。本文所述实例也依然使用ExpandableList，但是要实现的是3级树形菜单。

本文程序运行效果图如下图所示：

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 * 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 * 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>();
}

* 树形菜单可以用如下，子项是二级树形菜单的结构体如下所示：

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 * 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 * 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。

此外还需要注意：本文在解决No.2关键点的时候，只能取得第 * 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 * 菜单
       {
       node.childs.add(child_grandson[ii][1][iii]);
       }
       superNode.childs.add(node);
      }
     superTreeNode.add(superNode);
    }
    superAdapter.UpdateTreeNode(superTreeNode);
    expandableList.setAdapter(superAdapter);
 }
}
 }
 /**
  * * 树形菜单的事件不再可用，本函数由 * 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 * 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 * 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;
}
/**
* * 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 * 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。

希望本文所述代码对大家进行Android程序设计有一定的帮助。