Android树形控件的实现方法

在PC上我们已经习惯了树形控件，因为其可以清晰的展现各个节点之间的层次结果，但是在Android平台上，系统并没有提供这样一个控件，而是只有ListView。不过通过改写与ListView绑定的Adapter可以实现这样一个效果。

一个ListView需要和一个Adapter绑定，用于管理数据。在这里以BaseAdapter为例，继承Adapter需要重写四个函数，其中较为重要的是两个：
   1 public int getCount()；//该函数返回ListView 的ListItem的条数
   2 public View getView(int position, View view, ViewGroup arg2)//负责绘制每一个item。如果getCount（）返回10，那么getView（）就会被调用10次。

首先开发自己的数据结构：

package bupt.liyazhou.ui; 

import java.util.ArrayList;
import java.util.List; 

/*
 * @ author:liyazhou
 * @date:2013.4.29
 * @description:Node类用来在UI层中存储一个节点的信息
 *
 */
public class Node {
 private Node parent=null;//父节点
 private List<Node> children=null;
 private String oid=null;//该节点的oid
 private String name=null;//该节点信息的描述
 private String value=null;//该节点的值
 private boolean isLeaf=false;//是否为叶节点
 private boolean isExpanded=false;//该节点是否展开
 private int icon=-1;//该节点的图标对应的id
 private int iconForExpandedOrFolded=-1;
 private int iconForExpanding=-1;
 private int iconForFolding=-1;
 private boolean tableItemOrNot=false;//表示是否为表结构的一列 

 public Node(Node parent,String oid,String description,boolean isLeaf,int icon,int exIcon,int foIcon)
 {
  this.parent=parent;
  this.oid=oid;
  this.name=description;
  this.isLeaf=isLeaf;
  this.icon=icon;
  this.iconForExpanding=exIcon;
  this.iconForFolding=foIcon;
 }
 public void setTableItemOrNot(boolean tableItemOrNot)
 {
  this.tableItemOrNot=tableItemOrNot;
 }
 public boolean getTableItemOrNot()
 {
  return this.tableItemOrNot;
 }
 //设置value
 public void setValue(String value)
 {
  this.value=value;
 }
 //得到value
 public String getValue()
 {
  return this.value;
 }
 //设置图标
 public void setIcon(int icon)
 {
  this.icon=icon;
 }
 public int getIcon()
 {
  return this.icon;
 }
 //得到description
 public String getDescription()
 {
  return this.name;
 }
 //得到oid
 public String getOid()
 {
  return this.oid;
 }
 //得到是否为叶节点
 public boolean isLeafOrNot()
 {
  return this.isLeaf;
 }
 //得到当前节点所在的层数，根为0层
 public int getLevel()
 {
  return parent==null?0:parent.getLevel()+1;
 }
 //设置是否展开
 public void setExpanded(boolean isExpanded)
 {
  this.isExpanded=isExpanded;
 }
 public boolean getExpanded()
 {
  return this.isExpanded;
 }
 //添加子节点
 public void addChildNode(Node child)
 {
  if(this.children==null)
  {
   this.children=new ArrayList<Node>();
  }
  this.children.add(child);
 }
 //清空子节点
 public void clearChildren()
 {
  if(!this.children.equals(null))
  {
   this.children.clear();
  }
 }
 //是否为根节点
 public boolean isRoot()
 {
  return this.parent.equals(null)?true:false;
 }
 //设置展开图标
 public void setExpandIcon(int expand)
 {
  this.iconForExpanding=expand;
 }
 //设置折叠图标
 public void setFoldIcon(int fold)
 {
  this.iconForFolding=fold;
 }
 //得到展开或折叠图标
 public int getExpandOrFoldIcon()
 {
  if(this.isExpanded==true)
   return this.iconForExpanding;
  else
   return this.iconForFolding;
 }
 //得到子树
 public List<Node> getChildren()
 {
  return this.children;
 }
}

然后写自己的Adapter

package bupt.liyazhou.ui; 

import java.util.ArrayList;
import java.util.List; 

import android.R;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast; 

public class MibTreeListAdapter extends BaseAdapter {
 private Context context=null;
 private List<Node> nodeList=new ArrayList<Node> ();//所有的节点
 private List<Node> nodeListToShow=new ArrayList<Node>();//要展现的节点
 private LayoutInflater inflater=null;
 private Node root=null; 

 public MibTreeListAdapter(Context con,Node Root,int layout)
 {
  this.context=con;
  this.inflater=(LayoutInflater)con.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
  establishNodeList(Root);
  this.root=Root;
  setNodeListToShow();
 }
 public void establishNodeList(Node node)
 {
  nodeList.add(node);
  if(node.isLeafOrNot())
   return;
  List<Node> children=node.getChildren();
  for(int i=0;i<children.size();i++)
  {
   establishNodeList(children.get(i));
  }
 }
 public void setNodeListToShow()
 {
  this.nodeListToShow.clear();
  establishNodeListToShow(this.root);
 } 

 //构造要展示在listview的nodeListToShow
 public void establishNodeListToShow(Node node)
 {
  this.nodeListToShow.add(node);
  if(node.getExpanded()&&!node.isLeafOrNot()&&node.getChildren()!=null)
  {
   List<Node> children=node.getChildren();
   for(int i=0;i<children.size();i++)
   {
    establishNodeListToShow(children.get(i));
   }
  }
 } 

 //根据oid得到某一个Node,并更改其状态
 public void changeNodeExpandOrFold(int position)
 {
  String oid=this.nodeListToShow.get(position).getOid();
  for(int i=0;i<this.nodeList.size();i++)
  {
   if(nodeList.get(i).getOid().equals(oid))
   {
    boolean flag=nodeList.get(i).getExpanded();
    nodeList.get(i).setExpanded(!flag);
   } 

  }
 } 

 //listItem被点击的响应事件
 public Node OnListItemClick(int position)
 {
  Node node=this.nodeListToShow.get(position);
  if(node.isLeafOrNot())
  {
   //处理snmp代码
   Toast.makeText(this.context, "该节点为子节点", Toast.LENGTH_SHORT).show();
   return node;
  }
  else
  {
   this.changeNodeExpandOrFold(position);
   this.setNodeListToShow();
   this.notifyDataSetChanged();
   return null;
  }
 }
 public int getCount() {
  // TODO Auto-generated method stub
  return nodeListToShow.size();
 } 

 public Object getItem(int arg0) {
  // TODO Auto-generated method stub
  return nodeListToShow.get(arg0);
 } 

 public long getItemId(int arg0) {
  // TODO Auto-generated method stub
  return arg0;
 } 

 public View getView(int position, View view, ViewGroup parent) {
  // TODO Auto-generated method stub
  Holder holder=null;
  if(view!=null)
  {
   holder=(Holder)view.getTag();
  }
  else
  {
   holder=new Holder();
   view=this.inflater.inflate(bupt.liyazhou.R.layout.listview_item, null);
   holder.description=(TextView)view.findViewById(bupt.liyazhou.R.id.textview_nodeDescription);
   holder.nodeIcon=(ImageView)view.findViewById(bupt.liyazhou.R.id.imageview_nodeImage);
   holder.expandOrFoldIcon=(ImageView)view.findViewById(bupt.liyazhou.R.id.imageview_expandedImage);
   view.setTag(holder);
  } 

  //绘制一个item 

  //设置文字
  Node node= this.nodeListToShow.get(position);
  holder.description.setText(node.getDescription()); 

  //设置图标
  int icon=node.getIcon();
  if(icon!=-1)
  {
   holder.nodeIcon.setImageResource(icon);
   holder.nodeIcon.setVisibility(View.VISIBLE);
  }
  else
   holder.nodeIcon.setVisibility(View.INVISIBLE); 

  //设置展开折叠图标
  if(!node.isLeafOrNot())
  {
   int expandIcon=node.getExpandOrFoldIcon();
   if(expandIcon==-1)
    holder.expandOrFoldIcon.setVisibility(View.INVISIBLE);
   else
   {
    holder.expandOrFoldIcon.setImageResource(expandIcon);
    holder.expandOrFoldIcon.setVisibility(View.VISIBLE);
   } 

  }
  else
  {
   holder.expandOrFoldIcon.setVisibility(View.INVISIBLE);
  }
  view.setPadding(node.getLevel()*35, 10, 10, 10);
  return view;
 } 

 public class Holder
 {
  TextView description;
  ImageView nodeIcon;
  ImageView expandOrFoldIcon;
 } 

}

listview_item.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent" >
 <ImageView
  android:id="@+id/imageview_nodeImage"
  android:layout_height="fill_parent"
  android:layout_width="wrap_content"
  android:layout_alignParentLeft="true"
  android:paddingRight="10dp"/>
 <TextView
  android:id="@+id/textview_nodeDescription"
  android:layout_height="fill_parent"
  android:layout_width="wrap_content"
  android:layout_toRightOf="@id/imageview_nodeImage"
  />
 <ImageView
  android:id="@+id/imageview_expandedImage"
  android:layout_height="fill_parent"
  android:layout_width="wrap_content"
  android:layout_alignParentRight="true"/> 

</RelativeLayout>

实现效果：

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