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("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": 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": "顶级节点"
}

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