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。