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：

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持小牛知识库。