Android 树形控件的开发

   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：