java树形结构泛型

阳光穿透心脏的1/2处 2022-05-19 23:09 271阅读 0赞

定义一个上下级的类

import java.io.Serializable;
    import java.util.ArrayList;
    import java.util.List;
    
    public class TreeEntity<T> implements Serializable {
    
    	/**
    	 * 
    	 */
    	private static final long serialVersionUID = -1303781676719137068L;
    	/**
    	 * 
    	 */
    	private T model;
    	public T getModel() {
    		return model;
    	}
    	public void setModel(T model) {
    		this.model = model;
    	}
    	public List<TreeEntity<T>> getChildren() {
    		return children;
    	}
    	public void setChildren(List<TreeEntity<T>> children) {
    		if(this.children ==null){
    			this.children=new ArrayList<TreeEntity<T>>();
    		}
    		this.children = children;
    	}
    	private List<TreeEntity<T>> children;
    }

定义一个生成 树形的类

package com.qdcan.basecomm.util;
    
    import java.lang.reflect.Method;
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.HashSet;
    import java.util.Iterator;
    import java.util.LinkedHashMap;
    import java.util.LinkedHashSet;
    import java.util.List;
    import java.util.Map;
    import java.util.Set;
    
    import com.qdcan.entity.TreeEntity;
    
    /**
     * 获取树形结构
     * 
     * @author dypeng
     *
     */
    public class TreeUtil<T> {
    	private String getidMethod;
    	private String getParentidMethod;
    
    	public TreeUtil(String GetidMethod,String GetParentidMethod) {
    		this.getidMethod = GetidMethod;
    		this.getParentidMethod=GetParentidMethod;
    	}
    
    	/**
    	 * 向下获取树结构
    	 * 
    	 * @param channelid
    	 * @return
    	 * @throws Exception
    	 */
    	public List<T> createTree(Set<T> setall) throws Exception {
    		List<T> list = new ArrayList<T>();
    		Map<Long, Set<T>> listhash = new HashMap<Long, Set<T>>();
    		if (setall == null || setall.size() == 0) {
    			return null;
    		}
    
    		for (T item : setall) {
    			Long parentid = getParentid(item);
    			if (listhash.containsKey(parentid)) {
    				listhash.get(parentid).add(item);
    			} else {
    				Set<T> t = new HashSet<T>();
    				t.add(item);
    				listhash.put(parentid, t);
    			}
    		}
    		Iterator<T> iterator = listhash.get(0l).iterator();
    		while (iterator.hasNext()) {
    			T item = iterator.next();
    			list.add(item);
    			getlow(item, listhash, list);
    		}
    		return list;
    	}
    
    	private void getlow(T parent, Map<Long, Set<T>> list, List<T> getlist) throws Exception {
    		Long parentid = getid(parent);
    		if (list.containsKey(parentid)) {
    			Set<T> lp = list.get(parentid);
    			for (T item : lp) {
    				getlist.add(item);
    				getlow(item, list, getlist);
    			}
    		}
    		return;
    	}
    
    	public List<TreeEntity<T>> createTreeAsTreeEntity(Set<T> setall) throws Exception {
    		Map<Long, Set<TreeEntity<T>>> listhash = new LinkedHashMap<Long, Set<TreeEntity<T>>>();
    		if (setall == null || setall.size() == 0) {
    			return null;
    		}
    
    		for (T item : setall) {
    			Long parentid = getParentid(item);
    			if (listhash.containsKey(parentid)) {
    				TreeEntity<T> et =new TreeEntity<T>();
    				et.setModel(item);
    				listhash.get(parentid).add(et);
    			} else {
    				Set<TreeEntity<T>> t = new LinkedHashSet<TreeEntity<T>>();
    				TreeEntity<T> et =new TreeEntity<T>();
    				et.setModel(item);
    				t.add(et);
    				listhash.put(parentid, t);
    			}
    		}
    		Iterator<TreeEntity<T>> iterator = listhash.get(0l).iterator();
    		while (iterator.hasNext()) {
    			TreeEntity<T> entitys = iterator.next();
    			getlowasTreeEntity(entitys, listhash);
    		}
    		return new ArrayList(listhash.get(0l));
    	}
    	private void getlowasTreeEntity(TreeEntity<T> parent, Map<Long, Set<TreeEntity<T>>> list) throws Exception {
    		Long id = getid(parent.getModel());
    		if (list.containsKey(id)) {
    			if(list.get(id)!=null){
    				parent.setChildren(new ArrayList(list.get(id)));
    				for(TreeEntity<T> t:parent.getChildren()){
    					getlowasTreeEntity(t,list);
    				}			
    			}			
    		}
    	}
    	/**
    	 * 获取父级id
    	 * 
    	 * @param item
    	 * @return
    	 * @throws Exception
    	 */
    	private Long getid(T item) throws Exception {
    		Method method = item.getClass().getMethod(getidMethod, null);
    		Object invoke = method.invoke(item, null);
    		Long id = 0l;
    		if (invoke != null) {
    			id = Long.parseLong(invoke.toString());
    		}
    		return id;
    	}
    	/**
    	 * 获取父级id
    	 * 
    	 * @param item
    	 * @return
    	 * @throws Exception
    	 */
    	private Long getParentid(T item) throws Exception {
    		Method method = item.getClass().getMethod(getParentidMethod, null);
    		Object invoke = method.invoke(item, null);
    		Long parentid = 0l;
    		if (invoke != null) {
    			parentid = Long.parseLong(invoke.toString());
    		}
    		return parentid;
    	}
    }

3.使用方式

private void test1(){
    		TreeUtil<Menus> treeutil = new TreeUtil<Menus>("getId","getParentid");
    		Menus m = new Menus();
    		m.setId(1);
    		m.setParentid(0);
    		Menus m1 = new Menus();
    		m1.setId(2);
    		m1.setParentid(1);
    		Menus m2 = new Menus();
    		m2.setId(3);
    		m2.setParentid(2);
    		List<Menus> setall = Arrays.asList(new Menus[]{m,m1,m2});
    		
    		try {
    			
    			List<TreeEntity<Menus>> menusTree = treeutil.createTreeAsTreeEntity(new HashSet<Menus>(setall)) ;
    		} catch (Exception e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    	}