JAVA 根据数据库表内容生产树结构JSON数据的实例代码

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() == 0) {
      root = topnodes.get(0);
    } else {
      root.setid("-1");
      root.setparentid("");
      root.setparent(false);
      root.setchildren(true);
      root.setchecked(true);
      root.setchildren(topnodes);
      root.settext("*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": true,
  "children": [
    {
      "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"
    }
  ],
  "id": "-1",
  "parent": false,
  "parentid": "",
  "state": "open",
  "text": "*节点"
}