从数据库读取数据并动态生成easyui tree构结

一、 数据库表结构

二、从后台读取数据库生成easyui tree结构的树

1、TreeNode树结点类（每个结点都包含easyui tree 的基本属性信息）

import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
 
public class TreeNode implements Serializable  {
 
    private String id;
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    private String text;
    public String getText() {
        return text;
    }
    public void setText(String text) {
        this.text = text;
    }
    private String parentid;
    public String getParentid() {
        return parentid;
    }
    public void setParentid(String parentid) {
        this.parentid = parentid;
    }
 
    private List<TreeNode> children = new ArrayList<TreeNode>();
    public List<TreeNode> getChildren() {
        return children;
    }
    public void setChildren(List<TreeNode> children) {
        this.children = children;
    }
 
    private String iconCls;
    public String getIconCls() {
        return iconCls;
    }
    public void setIconCls(String iconCls) {
        this.iconCls = iconCls;
    }
 
    private String state;//节点状态，'open' 或 'closed'，默认：'open'。
    public String getState() {
        return state;
    }
    public void setState(String state) {
        this.state = state;
    }
 
    private boolean checked;
    public boolean isChecked() {
        return checked;
    }
    public void setChecked(boolean checked) {
        this.checked = checked;
    }
 
    private Map<String, Object> attributes = new HashMap<String, Object>();
    public Map<String, Object> getAttributes() {
        return attributes;
    }
    public void setAttributes(Map<String, Object> attributes) {
        this.attributes = attributes;
    }
 
}

2、用递归方法生成easyui tree 格式的json字符串

public static TreeNode recursiveTree(String id) {
        // 根据id获取节点对象(SELECT * FROM ttree t WHERE t.id=?)
        TreeNode node = getTreeNode(id);
        // 查询id下的所有子节点(SELECT * FROM ttree t WHERE t.parentid=?)
        List<TreeNode> childTreeNodes = queryTreeNode(id);
        // 遍历子节点
        for (TreeNode child :childTreeNodes) {
            TreeNode n = recursiveTree(child.getId()); // 递归
            node.getChildren().add(n);
        }
        return node;
    }

private static TreeNode getTreeNode(String id){
        TreeNode treeNode = null;
        Connection dbConn = getDbConnection();
        if(dbConn != null){
            try {
                String strSQL = "select * from ttree where id="+id;
                PreparedStatement pstmt = null;
                ResultSet rs = null;
                pstmt = dbConn.prepareStatement(strSQL);
                rs = pstmt.executeQuery();
                while (rs.next()) {
                    treeNode = new TreeNode();
                    treeNode.setId(rs.getString("id"));
                    treeNode.setText(rs.getString("text"));
                    treeNode.setParentid(rs.getString("parentid"));
                    Map<String, Object> attributes = new HashMap<String, Object>();
                    attributes.put("url",rs.getString("url"));
                    treeNode.setAttributes(attributes);
                }
                rs.close();
                pstmt.close();
                dbConn.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return treeNode;
    }

private static List<TreeNode> queryTreeNode(String id){
        List<TreeNode> arrList = new ArrayList<TreeNode>();
        Connection dbConn = getDbConnection();
        TreeNode treeNode = null;
        if(dbConn != null){
            try {
                String strSQL = "select * from ttree where parentid="+id;
                PreparedStatement pstmt = null;
                ResultSet rs = null;
                pstmt = dbConn.prepareStatement(strSQL);
                rs = pstmt.executeQuery();
                while (rs.next()) {
                    treeNode = new TreeNode();
                    treeNode.setId(rs.getString("id"));
                    treeNode.setText(rs.getString("text"));
                    treeNode.setParentid(rs.getString("parentid"));
                    Map<String, Object> attributes = new HashMap<String, Object>();
                    attributes.put("url",rs.getString("url"));
                    treeNode.setAttributes(attributes);
                    arrList.add(treeNode);
                }
                rs.close();
                pstmt.close();
                dbConn.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return arrList;
    }

3、测试调用(JSON.toJSONString方法是使用的fastjson.jar包中的方法功能很强大强烈推荐，可以在网上下载)

public static void main(String[] args) {
        TreeNode node = recursiveTree("1");
        String jsonText = JSON.toJSONString(node, true);
        System.out.println(jsonText);
}

4、输出结果

{
    "attributes":{
        "url":"1"
    },
    "checked":false,
    "children":[{
        "attributes":{
            "url":"2"
        },
        "checked":false,
        "children":[
            {
                "attributes":{
                    "url":"3"
                },
                "checked":false,
                "children":[],
                "id":"3",
                "parentid":"2",
                "text":"长沙"
            },
            {
                "attributes":{
                    "url":"4"
                },
                "checked":false,
                "children":[],
                "id":"4",
                "parentid":"2",
                "text":"株洲"
            },
            {
                "attributes":{
                    "url":"5"
                },
                "checked":false,
                "children":[],
                "id":"5",
                "parentid":"2",
                "text":"湘潭"
            },
            {
                "attributes":{
                    "url":"6"
                },
                "checked":false,
                "children":[
                    {
                        "attributes":{
                            "url":"7"
                        },
                        "checked":false,
                        "children":[],
                        "id":"7",
                        "parentid":"6",
                        "text":"岳阳县"
                    },
                    {
                        "attributes":{
                            "url":"http://192.168.1.1"
                        },
                        "checked":false,
                        "children":[],
                        "id":"8",
                        "parentid":"6",
                        "text":"华容县"
                    },
                    {
                        "attributes":{
                            "url":"9"
                        },
                        "checked":false,
                        "children":[],
                        "id":"9",
                        "parentid":"6",
                        "text":"湘阴县"
                    }
                ],
                "id":"6",
                "parentid":"2",
                "text":"岳阳"
            }
        ],
        "id":"2",
        "parentid":"1",
        "text":"湖南"
    }],
    "id":"1",
    "parentid":"0",
    "text":"中国"
}

写得很简单代码不是很规范，只是个测试demo。但功能很实用，希望对做web开发同学有些帮助。