JAVA 根據數據庫表內容生產樹結構JSON數據的實例代碼

1、利用場景

組織機構樹，通常會有組織機構表，其中有code(代碼),pcode(上級代碼),name(組織名稱)等字段

2、構造數據（以下數據並不是組織機構數據，而純屬本人胡編亂造的數據）

 List<Tree<Test>> trees = new ArrayList<Tree<Test>>();tests.add(new Test("0", "", "關於本人"));tests.add(new Test("1", "0", "技術學習"));tests.add(new Test("2", "0", "興趣"));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", "騎行"));tests.add(new Test("10", "2", "吃喝玩樂"));tests.add(new Test("11", "2", "學習"));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、源碼

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> { /** * 節點ID */ private String id; /** * 顯示節點文本*/ private String text; /** * 節點狀態，open closed */ private String state = "open"; /** * 節點是否被選中true false */ private boolean checked = false; /** * 節點屬性*/ private List<Map<String, Object>> attributes; /** * 節點的子節點*/ private List<Tree<T>> children = new ArrayList<Tree<T>>(); /** * 父ID */ private String parentId; /** * 是否有父節點*/ private boolean isParent = false; /** * 是否有子節點*/ 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;/** * 構建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("頂級節點"); } 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", "", "關於本人")); tests.add(new Test("1", "0", "技術學習")); tests.add(new Test("2", "0", "興趣")); 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", "騎行")); tests.add(new Test("10", "2", "吃喝玩樂")); tests.add(new Test("11", "2", "學習")); 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、運行結果

JSON數據：

 { "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": "技術學習" }, { "checked": false, "children": [ { "checked": false, "children": [], "id": "9", "parent": true, "parentId": "2", "state": "open", "text": "騎行" }, { "checked": false, "children": [], "id": "10", "parent": true, "parentId": "2", "state": "open", "text": "吃喝玩樂" }, { "checked": false, "children": [], "id": "11", "parent": true, "parentId": "2", "state": "open", "text": "學習" }, { "checked": false, "children": [], "id": "17", "parent": true, "parentId": "2", "state": "open", "text": "等等" } ], "id": "2", "parent": true, "parentId": "0", "state": "open", "text": "興趣" } ], "id": "0", "parent": false, "parentId": "", "state": "open", "text": "關於本人" } ], "id": "-1", "parent": false, "parentId": "", "state": "open", "text": "頂級節點"}