Java中使用List递归生成下拉列表树

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先看看效果

示例图片

bean类：

1 package com.lemsun.jtreport.beans.workflow;
2
3 /**
4  * SysAuditotypecategory entity.
5  *
6  * @author MyEclipse Persistence Tools
7  */
8
9 public class SysAuditotypecategory implements java.io.Serializable {
10
11     // Fields
12
13     private Long id;
14     private String categoryname;
15     private SysAuditotypecategory parent;
16     // Constructors
17
18     /** default constructor */
19     public SysAuditotypecategory() {
20     }
21
22     /** full constructor */
23     public SysAuditotypecategory(String categoryname) {
24         this.categoryname = categoryname;
25         this.parent = new SysAuditotypecategory();
26     }
27
28     // Property accessors
29
30     public Long getId() {
31         return this.id;
32     }
33
34     public void setId(Long id) {
35         this.id = id;
36     }
37
38     public String getCategoryname() {
39         return this.categoryname;
40     }
41
42     public void setCategoryname(String categoryname) {
43         this.categoryname = categoryname;
44     }
45
46     public SysAuditotypecategory getParent() {
47         return this.parent;
48     }
49
50     public void setParent(SysAuditotypecategory parent) {
51         this.parent = parent;
52     }
53
54 }

action中生成下拉树的代码

1     //=================begin-取得类型树=================
2     //传入所有的列表节点
3     private List<SysAuditotypecategory> cTreeList(List<SysAuditotypecategory> aList){
4         List<SysAuditotypecategory> returnList = new ArrayList<SysAuditotypecategory>();
5         List<SysAuditotypecategory> topList = new ArrayList<SysAuditotypecategory>();
6         List<SysAuditotypecategory> tempList = new ArrayList<SysAuditotypecategory>();
7
8         //筛选出顶级节点
9         for (SysAuditotypecategory sacty : aList) {
10             if(sacty.getParent()==null){
11                 topList.add(sacty);//是顶级节点
12             }else {
13                 tempList.add(sacty);//不是顶级节点
14             }
15         }
16
17         //获取子级节点列表
18         for (int i=0;i<topList.size();i++) {
19                 SysAuditotypecategory sacty = topList.get(i);
20                 returnList.add(cTreeNode(sacty, "", (i+1<topList.size())));//添加自身
21
22                 //添加所有子级，自身如果不是顶级节点列表的最后一个前面用“│”打头，如果是则用“…”打头。
23                 returnList.addAll(cTreeNodeList(tempList,sacty.getId(),(i+1<topList.size())?"│":"…"));
24             }
25         return returnList;
26     }
27
28     /**
29     * 按照父节点取得所有子节点
30     * @inList 所有不是顶级节点的列表
31     * @parentid 顶级节点的id
32     * @headString 前缀字符
33     */
34     private List<SysAuditotypecategory> cTreeNodeList(List<SysAuditotypecategory> inList,Long parentid,String headString){
35         List<SysAuditotypecategory> tempList1 = new ArrayList<SysAuditotypecategory>();
36         List<SysAuditotypecategory> tempList2 = new ArrayList<SysAuditotypecategory>();
37         List<SysAuditotypecategory> returnList = new ArrayList<SysAuditotypecategory>();
38
39         //取得兄弟节点和不是兄弟节点
40         for(int i=0;i<inList.size();i++){
41             SysAuditotypecategory sacty = inList.get(i);
42             if(sacty.getParent().getId() == parentid){
43                 tempList1.add(sacty);//兄弟节点
44             }else {
45                 tempList2.add(sacty);//子节点
46             }
47         }
48
49         if(tempList1.size()>0){
50             for(int i=0;i<tempList1.size();i++){
51                 SysAuditotypecategory sacty1 = tempList1.get(i);
52                 //返回列表添加自身
53                 returnList.add(cTreeNode(sacty1, headString, (i+1<tempList1.size())));
54
55                 //子节点个数不为0这递归这个方法。
56                 if(tempList2.size()>0){
57                     returnList.addAll(cTreeNodeList(tempList2,sacty1.getId(),headString+((i+1<tempList1.size())?"│":"…")));
58                 }
59             }
60         }
61
62         return returnList;
63     }
64
65     private SysAuditotypecategory cTreeNode(SysAuditotypecategory satcy,String headString,boolean havenext) {
66         satcy.setCategoryname(headString.concat((havenext?"├":"└"))+satcy.getCategoryname());//添加本身，不是最末节点在前面添加"├"，只最末节点这添加"└"
67         return satcy;
68     }
69     //=================end-取得类型树=================