JAVA 根据数据库表内容生产树结构JSON数据

1、利用场景

　　组织机构树，通常会有组织机构表，其中有code(代码),pcode(上级代码),name(组织名称)等字段

2、构造数据（以下数据并不是组织机构数据，而纯属本人胡编乱造的数据）

 List<Tree<Test>> trees = new ArrayList<Tree<Test>>();
 tests.add(new Test("0", "", "关于本人"));
 tests.add(new Test("1", "0", "技术学习"));
 tests.add(new Test("2", "0", "兴趣"));
 tests.add(new Test("3", "1", "JAVA"));
 tests.add(new Test("4", "1", "oracle"));
 tests.add(new Test("5", "1", "spring"));
 tests.add(new Test("6", "1", "springmvc"));
 tests.add(new Test("7", "1", "fastdfs"));
 tests.add(new Test("8", "1", "linux"));
 tests.add(new Test("9", "2", "骑行"));
 tests.add(new Test("10", "2", "吃喝玩乐"));
 tests.add(new Test("11", "2", "学习"));
 tests.add(new Test("12", "3", "String"));
 tests.add(new Test("13", "4", "sql"));
 tests.add(new Test("14", "5", "ioc"));
 tests.add(new Test("15", "5", "aop"));
 tests.add(new Test("16", "1", "等等"));
 tests.add(new Test("17", "2", "等等"));
 tests.add(new Test("18", "3", "等等"));
 tests.add(new Test("19", "4", "等等"));
 tests.add(new Test("20", "5", "等等"));

3、源码

Tree.java

 package pers.kangxu.datautils.bean.tree;

 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;

 import com.alibaba.fastjson.JSON;

 /**
  * tree TODO <br>
  *
  * @author kangxu2 2017-1-7
  *
  */
 public class Tree<T> {
     /**
      * 节点ID
      */
     private String id;
     /**
      * 显示节点文本
      */
     private String text;
     /**
      * 节点状态，open closed
      */
     private String state = "open";
     /**
      * 节点是否被选中 true false
      */
     private boolean checked = false;
     /**
      * 节点属性
      */
     private List<Map<String, Object>> attributes;
     /**
      * 节点的子节点
      */
     private List<Tree<T>> children = new ArrayList<Tree<T>>();

     /**
      * 父ID
      */
     private String parentId;
     /**
      * 是否有父节点
      */
     private boolean isParent = false;
     /**
      * 是否有子节点
      */
     private boolean isChildren = false;

     public String getId() {
         return id;
     }

     public void setId(String id) {
         this.id = id;
     }

     public String getText() {
         return text;
     }

     public void setText(String text) {
         this.text = text;
     }

     public String getState() {
         return state;
     }

     public void setState(String state) {
         this.state = state;
     }

     public boolean isChecked() {
         return checked;
     }

     public void setChecked(boolean checked) {
         this.checked = checked;
     }

     public List<Map<String, Object>> getAttributes() {
         return attributes;
     }

     public void setAttributes(List<Map<String, Object>> attributes) {
         this.attributes = attributes;
     }

     public List<Tree<T>> getChildren() {
         return children;
     }

     public void setChildren(List<Tree<T>> children) {
         this.children = children;
     }

     public boolean isParent() {
         return isParent;
     }

     public void setParent(boolean isParent) {
         this.isParent = isParent;
     }

     public boolean isChildren() {
         return isChildren;
     }

     public void setChildren(boolean isChildren) {
         this.isChildren = isChildren;
     }

     public String getParentId() {
         return parentId;
     }

     public void setParentId(String parentId) {
         this.parentId = parentId;
     }

     public Tree(String id, String text, String state, boolean checked,
             List<Map<String, Object>> attributes, List<Tree<T>> children,
             boolean isParent, boolean isChildren, String parentID) {
         super();
         this.id = id;
         this.text = text;
         this.state = state;
         this.checked = checked;
         this.attributes = attributes;
         this.children = children;
         this.isParent = isParent;
         this.isChildren = isChildren;
         this.parentId = parentID;
     }

     public Tree() {
         super();
     }

     @Override
     public String toString() {

         return JSON.toJSONString(this);
     }

 }

BuildTree.java

 package pers.kangxu.datautils.common.tree;

 import java.util.ArrayList;
 import java.util.List;

 import pers.kangxu.datautils.bean.tree.Tree;

 /**
  * 构建tree
  * TODO
  * <br>
  * @author kangxu2 2017-1-7
  *
  */
 public class BuildTree {

     /**
      *
      * TODO
      * <br>
      * @author kangxu2 2017-1-7
      *
      * @param nodes
      * @return
      */
     public static <T> Tree<T> build(List<Tree<T>> nodes) {

         if(nodes == null){
             return null;
         }
         List<Tree<T>> topNodes = new ArrayList<Tree<T>>();

         for (Tree<T> children : nodes) {

             String pid = children.getParentId();
             if (pid == null || "".equals(pid)) {
                 topNodes.add(children);

                 continue;
             }

             for (Tree<T> parent : nodes) {
                 String id = parent.getId();
                 if (id != null && id.equals(pid)) {
                     parent.getChildren().add(children);
                     children.setParent(true);
                     parent.setChildren(true);

                     continue;
                 }
             }

         }

         Tree<T> root = new Tree<T>();
         if (topNodes.size() == 1) {
             root = topNodes.get(0);
         } else {
             root.setId("-1");
             root.setParentId("");
             root.setParent(false);
             root.setChildren(true);
             root.setChecked(true);
             root.setChildren(topNodes);
             root.setText("顶级节点");

         }

         return root;
     }

 }

BuildTreeTester.java

 package pers.kangxu.datautils.test;

 import java.util.ArrayList;
 import java.util.List;

 import pers.kangxu.datautils.bean.tree.Tree;
 import pers.kangxu.datautils.common.tree.BuildTree;

 public class BuildTreeTester {

     public static void main(String[] args) {

         List<Tree<Test>> trees = new ArrayList<Tree<Test>>();
         List<Test> tests = new ArrayList<Test>();
         tests.add(new Test("0", "", "关于本人"));
         tests.add(new Test("1", "0", "技术学习"));
         tests.add(new Test("2", "0", "兴趣"));
         tests.add(new Test("3", "1", "JAVA"));
         tests.add(new Test("4", "1", "oracle"));
         tests.add(new Test("5", "1", "spring"));
         tests.add(new Test("6", "1", "springmvc"));
         tests.add(new Test("7", "1", "fastdfs"));
         tests.add(new Test("8", "1", "linux"));
         tests.add(new Test("9", "2", "骑行"));
         tests.add(new Test("10", "2", "吃喝玩乐"));
         tests.add(new Test("11", "2", "学习"));
         tests.add(new Test("12", "3", "String"));
         tests.add(new Test("13", "4", "sql"));
         tests.add(new Test("14", "5", "ioc"));
         tests.add(new Test("15", "5", "aop"));
         tests.add(new Test("16", "1", "等等"));
         tests.add(new Test("17", "2", "等等"));
         tests.add(new Test("18", "3", "等等"));
         tests.add(new Test("19", "4", "等等"));
         tests.add(new Test("20", "5", "等等"));

         for (Test test : tests) {
             Tree<Test> tree = new Tree<Test>();
             tree.setId(test.getId());
             tree.setParentId(test.getPid());
             tree.setText(test.getText());

             trees.add(tree);
         }

         Tree<Test> t = BuildTree.build(trees);
         System.out.println(t);
     }
 }

 class Test {

     private String id;
     private String pid;
     private String text;

     public String getId() {
         return id;
     }

     public void setId(String id) {
         this.id = id;
     }

     public String getPid() {
         return pid;
     }

     public void setPid(String pid) {
         this.pid = pid;
     }

     public String getText() {
         return text;
     }

     public void setText(String text) {
         this.text = text;
     }

     public Test(String id, String pid, String text) {
         super();
         this.id = id;
         this.pid = pid;
         this.text = text;
     }

     public Test() {
         super();
     }

     @Override
     public String toString() {
         return "Test [id=" + id + ", pid=" + pid + ", text=" + text + "]";
     }

 }

4、运行结果

JSON数据：

 {
     "checked":false,
     "children":[
         {
             "checked":false,
             "children":[
                 {
                     "checked":false,
                     "children":[
                         {
                             "checked":false,
                             "children":[

                             ],
                             "id":"12",
                             "parent":true,
                             "parentId":"3",
                             "state":"open",
                             "text":"String"
                         },
                         {
                             "checked":false,
                             "children":[

                             ],
                             "id":"18",
                             "parent":true,
                             "parentId":"3",
                             "state":"open",
                             "text":"等等"
                         }
                     ],
                     "id":"3",
                     "parent":true,
                     "parentId":"1",
                     "state":"open",
                     "text":"JAVA"
                 },
                 {
                     "checked":false,
                     "children":[
                         {
                             "checked":false,
                             "children":[

                             ],
                             "id":"13",
                             "parent":true,
                             "parentId":"4",
                             "state":"open",
                             "text":"sql"
                         },
                         {
                             "checked":false,
                             "children":[

                             ],
                             "id":"19",
                             "parent":true,
                             "parentId":"4",
                             "state":"open",
                             "text":"等等"
                         }
                     ],
                     "id":"4",
                     "parent":true,
                     "parentId":"1",
                     "state":"open",
                     "text":"oracle"
                 },
                 {
                     "checked":false,
                     "children":[
                         {
                             "checked":false,
                             "children":[

                             ],
                             "id":"14",
                             "parent":true,
                             "parentId":"5",
                             "state":"open",
                             "text":"ioc"
                         },
                         {
                             "checked":false,
                             "children":[

                             ],
                             "id":"15",
                             "parent":true,
                             "parentId":"5",
                             "state":"open",
                             "text":"aop"
                         },
                         {
                             "checked":false,
                             "children":[

                             ],
                             "id":"20",
                             "parent":true,
                             "parentId":"5",
                             "state":"open",
                             "text":"等等"
                         }
                     ],
                     "id":"5",
                     "parent":true,
                     "parentId":"1",
                     "state":"open",
                     "text":"spring"
                 },
                 {
                     "checked":false,
                     "children":[

                     ],
                     "id":"6",
                     "parent":true,
                     "parentId":"1",
                     "state":"open",
                     "text":"springmvc"
                 },
                 {
                     "checked":false,
                     "children":[

                     ],
                     "id":"7",
                     "parent":true,
                     "parentId":"1",
                     "state":"open",
                     "text":"fastdfs"
                 },
                 {
                     "checked":false,
                     "children":[

                     ],
                     "id":"8",
                     "parent":true,
                     "parentId":"1",
                     "state":"open",
                     "text":"linux"
                 },
                 {
                     "checked":false,
                     "children":[

                     ],
                     "id":"16",
                     "parent":true,
                     "parentId":"1",
                     "state":"open",
                     "text":"等等"
                 }
             ],
             "id":"1",
             "parent":true,
             "parentId":"0",
             "state":"open",
             "text":"技术学习"
         },
         {
             "checked":false,
             "children":[
                 {
                     "checked":false,
                     "children":[

                     ],
                     "id":"9",
                     "parent":true,
                     "parentId":"2",
                     "state":"open",
                     "text":"骑行"
                 },
                 {
                     "checked":false,
                     "children":[

                     ],
                     "id":"10",
                     "parent":true,
                     "parentId":"2",
                     "state":"open",
                     "text":"吃喝玩乐"
                 },
                 {
                     "checked":false,
                     "children":[

                     ],
                     "id":"11",
                     "parent":true,
                     "parentId":"2",
                     "state":"open",
                     "text":"学习"
                 },
                 {
                     "checked":false,
                     "children":[

                     ],
                     "id":"17",
                     "parent":true,
                     "parentId":"2",
                     "state":"open",
                     "text":"等等"
                 }
             ],
             "id":"2",
             "parent":true,
             "parentId":"0",
             "state":"open",
             "text":"兴趣"
         }
     ],
     "id":"0",
     "parent":false,
     "parentId":"",
     "state":"open",
     "text":"关于本人"
 }