Android 多级菜单实现

　　在Android里要实现树形菜单，都是用ExpandableList，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。程序运行效果图：

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package eoe.demo;

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;
}
}