Android无限极树状(tree)结构Demo

上篇文章写了一下ExpandableListView，就是两层结构的点击，Android中没有三层结构的组件，这个时候需要自己去扩展一下，可以扩展ExpandableListView，也可以选择扩展ListView。为了是实现这个效果，也是在搜了很多文章（中国的文章你懂的），有个哥们在GitHub开源了项目，奈何封装的太多，看的头晕目眩。看到有人扩展ListView的更符合自己的想法，因为做服务器端的时候也是先加载顶层元素，然后控制点击事件加载父级下面的子元素，有这个理解就可以去是实现一颗所谓的N级结构，开始正题吧:

布局文件

新建一个activity_tree.xml布局文件，里面放一个ListView即可:

 

<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="com.example.googletree.TreeActivity" >  <ListView         android:id="@+id/tree_list"        android:layout_width="match_parent"        android:layout_height="match_parent"/></RelativeLayout>

 

　新建一个tree_item布局文件:

<?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/homeImg"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerVertical="true"        android:layout_alignParentLeft="true"/>        <TextView         android:id="@+id/treeText"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerVertical="true"        android:layout_toRightOf="@id/homeImg"/>    </RelativeLayout>

　Demo实现

需要展示一个树状结构的数据，先定义一个TreeNode类，存放数据:

 

public class TreeNode {/** 文字内容 */private String contentText;/** 在tree中的层级 */private int level;/** 元素的id */private int id;/** 父元素的id */private int parendId;/** 是否有子元素 */private boolean hasChildren;/** item是否展开 */private boolean isExpanded;/** 表示该节点没有父元素，也就是level为0的节点 */public static final int NO_PARENT = -1;/** 表示该元素位于最顶层的层级 */public static final int TOP_LEVEL = 0;public TreeNode(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;}}

 

　为了填充视图的中ListView，需要自定义TreeViewAdapter：

public class TreeViewAdapter extends BaseAdapter {/** 所有的数据集合 */private ArrayList<TreeNode> allNodes;/** 顶层元素结合*/private ArrayList<TreeNode> topNodes;/** LayoutInflater */private LayoutInflater inflater;/** item的行首缩进基数 */private int indentionBase;public TreeViewAdapter(ArrayList<TreeNode> topNodes, ArrayList<TreeNode> allNodes, LayoutInflater inflater) {this.topNodes = topNodes;this.allNodes = allNodes;this.inflater = inflater;indentionBase =20;}public ArrayList<TreeNode> getTopNodes() {return topNodes;}public ArrayList<TreeNode> getAllNodes() {return allNodes;}@Overridepublic int getCount() {return topNodes.size();}@Overridepublic Object getItem(int position) {return topNodes.get(position);}@Overridepublic long getItemId(int position) {return position;}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {ViewHolder holder = null;if (convertView == null) {holder = new ViewHolder();convertView = inflater.inflate(R.layout.tree_item, null);holder.homeImg = (ImageView) convertView.findViewById(R.id.homeImg);holder.treeText = (TextView) convertView.findViewById(R.id.treeText);convertView.setTag(holder);} else {holder = (ViewHolder) convertView.getTag();}TreeNode element = topNodes.get(position);int level =element.getLevel();holder.homeImg.setPadding(indentionBase * (level + 1), holder.homeImg.getPaddingTop(), holder.homeImg.getPaddingRight(), holder.homeImg.getPaddingBottom());holder.treeText.setText(element.getContentText());if (element.isHasChildren() && !element.isExpanded()) {holder.homeImg.setImageResource(R.drawable.open);//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.homeImg.setVisibility(View.VISIBLE);} else if (element.isHasChildren() && element.isExpanded()) {holder.homeImg.setImageResource(R.drawable.open);holder.homeImg.setVisibility(View.VISIBLE);} else if (!element.isHasChildren()) {holder.homeImg.setImageResource(R.drawable.open);holder.homeImg.setVisibility(View.VISIBLE);}return convertView;}static class ViewHolder{ImageView homeImg;TextView treeText;}}

　在Activity中的调用:　

public class TreeActivity extends Activity {/** 树中的顶层元素集合 */private ArrayList<TreeNode> topNodes;/** 所有的元素集合 */private ArrayList<TreeNode> allNodes;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_tree);LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);init();ListView treeview = (ListView) findViewById(R.id.tree_list);TreeViewAdapter treeViewAdapter = new TreeViewAdapter(topNodes, allNodes, inflater);TreeViewItemClickListener treeViewItemClickListener = new TreeViewItemClickListener(treeViewAdapter);treeview.setAdapter(treeViewAdapter);treeview.setOnItemClickListener(treeViewItemClickListener);}private void init() {topNodes = new ArrayList<TreeNode>();allNodes = new ArrayList<TreeNode>();//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TreeNode node1= new TreeNode("北京市", TreeNode.TOP_LEVEL, 0, TreeNode.NO_PARENT, true, false);//添加第一层节点TreeNode node2= new TreeNode("海淀区", TreeNode.TOP_LEVEL + 1, 1, node1.getId(), true, false);//添加第二层节点TreeNode node3= new TreeNode("西二旗", TreeNode.TOP_LEVEL + 2, 2, node2.getId(), true, false);//添加第三层节点//TreeNode node7= new TreeNode("辉煌国际", TreeNode.TOP_LEVEL + 3, 6, node3.getId(), false, false);//添加第一层节点TreeNode node4= new TreeNode("河南省", TreeNode.TOP_LEVEL , 3, TreeNode.NO_PARENT, true, false);//添加第二层节点TreeNode node5= new TreeNode("郑州市", TreeNode.TOP_LEVEL + 1, 4, node4.getId(), true, false);//添加第三层节点TreeNode node6= new TreeNode("金水区", TreeNode.TOP_LEVEL + 2, 5, node5.getId(), false, false);//添加初始树元素topNodes.add(node1);topNodes.add(node4);//创建数据源allNodes.add(node1);allNodes.add(node2);allNodes.add(node3);allNodes.add(node4);allNodes.add(node5);allNodes.add(node6);//allNodes.add(node7);}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {getMenuInflater().inflate(R.menu.tree, menu);return true;}}

由于每次都是加载一层节点，需要自己控制点击事件，自定义一个TreeViewItemClickListener:

public class TreeViewItemClickListener implements OnItemClickListener {/** 定义的适配器 */private TreeViewAdapter treeViewAdapter;public TreeViewItemClickListener(TreeViewAdapter treeViewAdapter) {this.treeViewAdapter = treeViewAdapter;}@Overridepublic void onItemClick(AdapterView<?> parent, View view, int position,long id) {//点击的item代表的元素TreeNode treeNode = (TreeNode) treeViewAdapter.getItem(position);//树中顶层的元素ArrayList<TreeNode> topNodes = treeViewAdapter.getTopNodes();//元素的数据源ArrayList<TreeNode> allNodes = treeViewAdapter.getAllNodes();//点击没有子项的item直接返回if (!treeNode.isHasChildren()) {return;}if (treeNode.isExpanded()) {treeNode.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<TreeNode> elementsToDel = new ArrayList<TreeNode>();for (int i = position + 1; i < topNodes.size(); i++) {if (treeNode.getLevel() >= topNodes.get(i).getLevel())break;elementsToDel.add(topNodes.get(i));}topNodes.removeAll(elementsToDel);treeViewAdapter.notifyDataSetChanged();} else {treeNode.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 (TreeNode e : allNodes) {if (e.getParendId() == treeNode.getId()) {e.setExpanded(false);topNodes.add(position + i, e);i ++;}}treeViewAdapter.notifyDataSetChanged();}}}

　代码搞定，看初始效果吧:

全部展开：

 

　这个时候把treeActivity中那个node7注释取消，也就是加了第三层节点的效果:

 

TreeNode node7= new TreeNode("辉煌国际", TreeNode.TOP_LEVEL + 3, 6, node3.getId(), false, false);

 

　　效果如下: