Android UI 之实现多级树形列表TreeView示例

所谓TreeView就是在Windows中常见的多级列表树，在Android中系统只默认提供了ListView和ExpandableListView两种列表，最多只支持到二级列表的实现，所以如果想要实现三级和更多层次的列表，就需要我们自己来做一些处理了。

其实这个效果很久以前就有人想办法实现了，但是实现的效果有一些问题，我的实现思路主要也是来自于网络，但是在其基础上修正了逻辑上的一些错误，做了一些优化。

先来看一下效果：

然后大体说一下思路：

其实这里实现的多级列表只是一个视觉效果，我们看到的分级效果是由于每行的缩进不同造成的。比如在上面的效果中，山东省和广东省是级别最高的层次，山东省下的青岛市作为山东省的子项，我们增加他的左缩进，这样看起来就有了层次感了。其他的层次也是同理。

也就是说，我们只用了一个ListView，工作的重点就在于不断变化ListView显示的数据，根据用户的操作，将数据修改为用户想要看到的数据内容，并根据每个数据项的不同，在显示效果上做不同的缩进处理，最终呈现出一个TreeView的效果。

具体的实现思路参考下面的项目结构和具体代码：

Element.Java:

package com.example.androidtreeviewdemo.treeview; 
 
public class Element { 
   
  private String contentText; 
   
  private int level; 
   
  private int id; 
   
  private int parendId; 
   
  private boolean hasChildren; 
   
  private boolean isExpanded; 
   
  public static final int NO_PARENT = -1; 
   
  public static final int TOP_LEVEL = 0; 
  public Element(String contentText, int level, int id, int parendId, 
      boolean hasChildren, boolean isExpanded) { 
    super(); 
    this.contentText = contentText; 
    this.level = level; 
    this.id = id; 
    this.parendId = parendId; 
    this.hasChildren = hasChildren; 
    this.isExpanded = isExpanded; 
  } 
  public boolean isExpanded() { 
    return isExpanded; 
  } 
  public void setExpanded(boolean isExpanded) { 
    this.isExpanded = isExpanded; 
  } 
  public String getContentText() { 
    return contentText; 
  } 
  public void setContentText(String contentText) { 
    this.contentText = contentText; 
  } 
  public int getLevel() { 
    return level; 
  } 
  public void setLevel(int level) { 
    this.level = level; 
  } 
  public int getId() { 
    return id; 
  } 
  public void setId(int id) { 
    this.id = id; 
  } 
  public int getParendId() { 
    return parendId; 
  } 
  public void setParendId(int parendId) { 
    this.parendId = parendId; 
  } 
  public boolean isHasChildren() { 
    return hasChildren; 
  } 
  public void setHasChildren(boolean hasChildren) { 
    this.hasChildren = hasChildren; 
  } 
} 

TreeViewAdapter.java:

package com.example.androidtreeviewdemo.treeview; 
import java.util.ArrayList; 
import com.example.androidtreeviewdemo.R; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.BaseAdapter; 
import android.widget.ImageView; 
import android.widget.TextView; 
 
public class TreeViewAdapter extends BaseAdapter { 
   
  private ArrayList<Element> elementsData; 
   
  private ArrayList<Element> elements; 
   
  private LayoutInflater inflater; 
   
  private int indentionBase; 
  public TreeViewAdapter(ArrayList<Element> elements, ArrayList<Element> elementsData, LayoutInflater inflater) { 
    this.elements = elements; 
    this.elementsData = elementsData; 
    this.inflater = inflater; 
    indentionBase = 50; 
  } 
  public ArrayList<Element> getElements() { 
    return elements; 
  } 
  public ArrayList<Element> getElementsData() { 
    return elementsData; 
  } 
  @Override 
  public int getCount() { 
    return elements.size(); 
  } 
  @Override 
  public Object getItem(int position) { 
    return elements.get(position); 
  } 
  @Override 
  public long getItemId(int position) { 
    return position; 
  } 
  @Override 
  public View getView(int position, View convertView, ViewGroup parent) { 
    ViewHolder holder = null; 
    if (convertView == null) { 
      holder = new ViewHolder(); 
      convertView = inflater.inflate(R.layout.treeview_item, null); 
      holder.disclosureImg = (ImageView) convertView.findViewById(R.id.disclosureImg); 
      holder.contentText = (TextView) convertView.findViewById(R.id.contentText); 
      convertView.setTag(holder); 
    } else { 
      holder = (ViewHolder) convertView.getTag(); 
    } 
    Element element = elements.get(position); 
    int level = element.getLevel(); 
    holder.disclosureImg.setPadding( 
        indentionBase * (level + 1),  
        holder.disclosureImg.getPaddingTop(),  
        holder.disclosureImg.getPaddingRight(),  
        holder.disclosureImg.getPaddingBottom()); 
    holder.contentText.setText(element.getContentText()); 
    if (element.isHasChildren() && !element.isExpanded()) { 
      holder.disclosureImg.setImageResource(R.drawable.close); 
      //这里要主动设置一下icon可见，因为convertView有可能是重用了"设置了不可见"的view，下同。 
      holder.disclosureImg.setVisibility(View.VISIBLE); 
    } else if (element.isHasChildren() && element.isExpanded()) { 
      holder.disclosureImg.setImageResource(R.drawable.open); 
      holder.disclosureImg.setVisibility(View.VISIBLE); 
    } else if (!element.isHasChildren()) { 
      holder.disclosureImg.setImageResource(R.drawable.close); 
      holder.disclosureImg.setVisibility(View.INVISIBLE); 
    } 
    return convertView; 
  } 
   
  static class ViewHolder{ 
    ImageView disclosureImg; 
    TextView contentText; 
  } 
} 

TreeViewItemClickListener.java:

package com.example.androidtreeviewdemo.treeview; 
import java.util.ArrayList; 
import android.view.View; 
import android.widget.AdapterView; 
import android.widget.AdapterView.OnItemClickListener; 
 
public class TreeViewItemClickListener implements OnItemClickListener { 
   
  private TreeViewAdapter treeViewAdapter; 
  public TreeViewItemClickListener(TreeViewAdapter treeViewAdapter) { 
    this.treeViewAdapter = treeViewAdapter; 
  } 
  @Override 
  public void onItemClick(AdapterView<?> parent, View view, int position, 
      long id) { 
    //点击的item代表的元素 
    Element element = (Element) treeViewAdapter.getItem(position); 
    //树中的元素 
    ArrayList<Element> elements = treeViewAdapter.getElements(); 
    //元素的数据源 
    ArrayList<Element> elementsData = treeViewAdapter.getElementsData(); 
    //点击没有子项的item直接返回 
    if (!element.isHasChildren()) { 
      return; 
    } 
    if (element.isExpanded()) { 
      element.setExpanded(false); 
      //删除节点内部对应子节点数据，包括子节点的子节点... 
      ArrayList<Element> elementsToDel = new ArrayList<Element>(); 
      for (int i = position + 1; i < elements.size(); i++) { 
        if (element.getLevel() >= elements.get(i).getLevel()) 
          break; 
        elementsToDel.add(elements.get(i)); 
      } 
      elements.removeAll(elementsToDel); 
      treeViewAdapter.notifyDataSetChanged(); 
    } else { 
      element.setExpanded(true); 
      //从数据源中提取子节点数据添加进树，注意这里只是添加了下一级子节点，为了简化逻辑 
      int i = 1;//注意这里的计数器放在for外面才能保证计数有效 
      for (Element e : elementsData) { 
        if (e.getParendId() == element.getId()) { 
          e.setExpanded(false); 
          elements.add(position + i, e); 
          i ++; 
        } 
      } 
      treeViewAdapter.notifyDataSetChanged(); 
    } 
  } 
} 

MainActivity.java:

package com.example.androidtreeviewdemo; 
import java.util.ArrayList; 
import com.example.androidtreeviewdemo.treeview.Element; 
import com.example.androidtreeviewdemo.treeview.TreeViewAdapter; 
import com.example.androidtreeviewdemo.treeview.TreeViewItemClickListener; 
import android.os.Bundle; 
import android.app.Activity; 
import android.content.Context; 
import android.view.LayoutInflater; 
import android.view.Menu; 
import android.widget.ListView; 
public class MainActivity extends Activity { 
   
  private ArrayList<Element> elements; 
   
  private ArrayList<Element> elementsData; 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
    init(); 
    ListView treeview = (ListView) findViewById(R.id.treeview); 
    TreeViewAdapter treeViewAdapter = new TreeViewAdapter( 
        elements, elementsData, inflater); 
    TreeViewItemClickListener treeViewItemClickListener = new TreeViewItemClickListener(treeViewAdapter); 
    treeview.setAdapter(treeViewAdapter); 
    treeview.setOnItemClickListener(treeViewItemClickListener); 
  } 
  private void init() { 
    elements = new ArrayList<Element>(); 
    elementsData = new ArrayList<Element>(); 
    //添加节点 -- 节点名称，节点level，节点id，父节点id，是否有子节点，是否展开 
    //添加最外层节点 
    Element e1 = new Element("山东省", Element.TOP_LEVEL, 0, Element.NO_PARENT, true, false); 
    //添加第一层节点 
    Element e2 = new Element("青岛市", Element.TOP_LEVEL + 1, 1, e1.getId(), true, false); 
    //添加第二层节点 
    Element e3 = new Element("市南区", Element.TOP_LEVEL + 2, 2, e2.getId(), true, false); 
    //添加第三层节点 
    Element e4 = new Element("香港中路", Element.TOP_LEVEL + 3, 3, e3.getId(), false, false); 
    //添加第一层节点 
    Element e5 = new Element("烟台市", Element.TOP_LEVEL + 1, 4, e1.getId(), true, false); 
    //添加第二层节点 
    Element e6 = new Element("芝罘区", Element.TOP_LEVEL + 2, 5, e5.getId(), true, false); 
    //添加第三层节点 
    Element e7 = new Element("凤凰台街道", Element.TOP_LEVEL + 3, 6, e6.getId(), false, false); 
    //添加第一层节点 
    Element e8 = new Element("威海市", Element.TOP_LEVEL + 1, 7, e1.getId(), false, false); 
    //添加最外层节点 
    Element e9 = new Element("广东省", Element.TOP_LEVEL, 8, Element.NO_PARENT, true, false); 
    //添加第一层节点 
    Element e10 = new Element("深圳市", Element.TOP_LEVEL + 1, 9, e9.getId(), true, false); 
    //添加第二层节点 
    Element e11 = new Element("南山区", Element.TOP_LEVEL + 2, 10, e10.getId(), true, false); 
    //添加第三层节点 
    Element e12 = new Element("深南大道", Element.TOP_LEVEL + 3, 11, e11.getId(), true, false); 
    //添加第四层节点 
    Element e13 = new Element("10000号", Element.TOP_LEVEL + 4, 12, e12.getId(), false, false); 
    //添加初始树元素 
    elements.add(e1); 
    elements.add(e9); 
    //创建数据源 
    elementsData.add(e1); 
    elementsData.add(e2); 
    elementsData.add(e3); 
    elementsData.add(e4); 
    elementsData.add(e5); 
    elementsData.add(e6); 
    elementsData.add(e7); 
    elementsData.add(e8); 
    elementsData.add(e9); 
    elementsData.add(e10); 
    elementsData.add(e11); 
    elementsData.add(e12); 
    elementsData.add(e13); 
  } 
  @Override 
  public boolean onCreateOptionsMenu(Menu menu) { 
    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.menu.activity_main, menu); 
    return true; 
  } 
} 

treeview_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/disclosureImg" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_centerVertical="true" 
    android:layout_alignParentLeft="true"/> 
  <TextView  
    android:id="@+id/contentText" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_centerVertical="true" 
    android:layout_toRightOf="@id/disclosureImg"/> 
</RelativeLayout> 

activity_main.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
  xmlns:tools="http://schemas.android.com/tools" 
  android:layout_width="match_parent" 
  android:layout_height="match_parent" 
  tools:context=".MainActivity" > 
  <ListView  
    android:id="@+id/treeview" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent"/> 
</RelativeLayout> 

下载地址：AndroidTreeViewDemo_jb51.rar

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