从数据库中读取列表用java语言转换成树形

从数据库中读取数据列表，通过后台代码将数据转换成树形，代码如下

 

/**

 * 树节点

 *

 */

public class TreeNode{

//节点id

private String id; 

//父节点id

private String parentId; 

//文本

private String text;

//节点状态

private String state = "open";

//是否选中

private Boolean isChecked = false;

//子节点集合

private List<TreeNode> children;

 

public TreeNode(){}

 

public TreeNode(String parentId,String id,String text){

this.id = id;

this.parentId = parentId;

this.text = text;

}

 

public TreeNode(String id,String parentId,String text,String state, Boolean isChecked){

this.id = id;

this.parentId = parentId;

this.text = text;

this.state = state;

this.isChecked = isChecked;

}

 

 

/**

* 返回json

* @return

*/

/* public String toJsonString(){

String result = "{"

           + "\"id\" : \"" + id + "\""

           + ", \"text\" : \"" + text + "\"";

        

        if (children != null && children.size() != 0) {

            result += ", \"children\" : " + children.toString();

        } else {

            result += ", \"leaf\" : true";

        }

                

return result + "}";

}*/

 

 

//get set

public String getId() {

return id;

}

public void setId(String id) {

this.id = id;

}

public String getParentId() {

return parentId;

}

public void setParentId(String parentId) {

this.parentId = parentId;

}

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 getIsChecked() {

return isChecked;

}

public void setIsChecked(Boolean isChecked) {

this.isChecked = isChecked;

}

public List<TreeNode> getChildren() {

return children;

}

public void setChildren(List<TreeNode> children) {

this.children = children;

}

}

 

 

 

/**

 * 将list展示成一棵树

 *

 */

public class ShowTreeUtils {

 

/**

* 将list转换成tree

* @param list

* @return

* @throws IOException 

*/

public static String showTree(List<TreeNode> menuList) throws IOException{

List<TreeNode> nodeList = new ArrayList<TreeNode>();  //存放父节点的list

 

for(TreeNode node1 : menuList){  

     boolean isChildMark = false;  //标志该节点是否是子节点，isChildMark为false表示不是子节点

     for(TreeNode node2 : menuList){  

         if(node1.getParentId()!=null && node1.getParentId().equals(node2.getId())){  

         isChildMark = true;  

             if(node2.getChildren() == null){

             node2.setChildren(new ArrayList<TreeNode>()); 

             }

             node2.getChildren().add(node1); 

             //node2.setState("closed");

             break;  

         } 

     }  

     if(!isChildMark){  

         nodeList.add(node1);   //将父节点放到nodeList中

     }  

 }

 

ObjectMapper mapper = new ObjectMapper();

String json = mapper.writeValueAsString(nodeList);

 

return json;

}

}

 

 

//测试类

public class TreeTest {

public static void main(String[] args) throws  IOException {

List<TreeNode> menuList = new ArrayList<TreeNode>();  

TreeNode root = new TreeNode("000000000000", "500000000000", "公共通讯录目录"); //根节点

TreeNode root1 = new TreeNode("000000000000", "600000000000", "个人通讯录目录"); //根节点

TreeNode b = new TreeNode("500000000000", "63000000000000000001", "青海省民政厅");

TreeNode c = new TreeNode("63000000000000000001", "63010000000000000002", "西宁");

TreeNode d = new TreeNode("63010000000000000002", "63010200000000000004", "城东");

TreeNode e = new TreeNode("63000000000000000001", "63210000000000000011", "海东");

TreeNode f = new TreeNode("63210000000000000011", "63212100000000000012", "平安");

TreeNode g = new TreeNode("63210000000000000011", "63212200000000000013", "民和");

TreeNode h = new TreeNode("63210000000000000011", "63212300000000000014", "乐都");

menuList.add(root);

menuList.add(root1);

menuList.add(b);

menuList.add(c);

menuList.add(d);

menuList.add(e);

menuList.add(f);

menuList.add(g);

menuList.add(h);

 

 

   //转为json格式        

   String json = ShowTreeUtils.showTree(menuList);

   System.out.println("json:"+json);  

 

}

 

}