在Android上实现树形控件

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：

1public int getCount()；//该函数返回ListView 的ListItem的条数

2public 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oidprivate 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idprivate 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valuepublic void setValue(String value){this.value=value;}//得到valuepublic 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descriptionpublic 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;elsereturn 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 stubreturn nodeListToShow.size();}public Object getItem(int arg0) {// TODO Auto-generated method stubreturn nodeListToShow.get(arg0);}public long getItemId(int arg0) {// TODO Auto-generated method stubreturn arg0;}public View getView(int position, View view, ViewGroup parent) {// TODO Auto-generated method stubHolder 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);}elseholder.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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