import java.lang.reflect.Field;
import java.lang.reflect.Method;

/**
 * 
 * @author zhangdapeng
 * @version 1.0,2014年5月13日
 * @since 1.0
 */
public class NodeWorker {
	/**
	 *自身id
	 */
	private String id;
	/**
	 * 父id
	 */
	private String pid;
	/**
	 * 节点内容
	 */
	private Object data;
	/**
	 * 孩子节点列表
	 */
	private ChildrenWorker children = new ChildrenWorker();

	public NodeWorker() {
	}

	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 Object getData() {
		return data;
	}

	public void setData(Object data) {
		this.data = data;
	}

	// 先序遍历，拼接JSON字符串
	public String toString() {
		Class<? extends Object> clazz = data.getClass();
		Field[] field = clazz.getDeclaredFields();

		String name = null;
		String value = null;
		StringBuilder result=new StringBuilder();
		for (int i = 0; i < field.length; i++) {
			name = field[i].getName();
			value = (String) invokeGet(data, name);
			if(i!=0){
				result.append(",").append('"' + name + '"' + ":" + '"' + value + '"');

			}else
			result.append("{").append('"' + name + '"' + ":" + '"' + value + '"');
		}


		if (children != null && children.getSize() != 0) {
			result.append(",").append('"').append("c").append('"').append(":").append(children.toString());
		} else {
//			result.append(",").append('"' + "leaf" + '"' + ":" + '"' + "true" + '"');
		}

		return result.append("}").toString();
	}

	/**
	 * java反射bean的get方法
	 * 
	 * @param objectClass
	 * @param fieldName
	 * @return
	 */
	@SuppressWarnings("unchecked")
	public Method getGetMethod(Class objectClass, String fieldName) {
		StringBuffer sb = new StringBuffer();
		sb.append("get");
		sb.append(fieldName.substring(0, 1).toUpperCase());
		sb.append(fieldName.substring(1));
		try {
			return objectClass.getMethod(sb.toString());
		} catch (Exception e) {
		}
		return null;
	}

	/**
	 * 执行get方法
	 * 
	 * @param o
	 *            执行对象
	 * @param fieldName
	 *            属性
	 */
	public Object invokeGet(Object o, String fieldName) {
		Method method = getGetMethod(o.getClass(), fieldName);
		try {
			return method.invoke(o, new Object[0]);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}
	
	// 添加孩子节点
	public void addChild(NodeWorker node) {
		this.children.addChild(node);
	}


}

/**
 * 
 */

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
 * @author zhangdapeng
 * @version 1.0,2014年1月19日
 * @since 1.0
 */
public class ChildrenWorker {
	private List<NodeWorker> list = new ArrayList<NodeWorker>();

	public int getSize() {
		return list.size();
	}

	public void addChild(NodeWorker node) {
		list.add(node);
	}

	// 拼接孩子节点的JSON字符串
	public String toString() {
		String result = "[";
		for (Iterator<NodeWorker> it = list.iterator(); it.hasNext();) {
			result += it.next().toString();
			result += ",";
		}
		result = result.substring(0, result.length() - 1);
		result += "]";
		return result;
	}
}

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.Map.Entry;

/**
 * @author zhangdapeng
 * @version 1.0,2014年5月13日
 * @since   1.0	
 */
public class MultiTreeBuilder {

	/**
	 * 
	 */
	public MultiTreeBuilder() {
		// TODO Auto-generated constructor stub
	}
	/**
	 * 安预定义排列
	 * @param list
	 * @return
	 */
	public String generateJson(List<NodeWorker> list) {
		// 节点列表（散列表，用于临时存储节点对象）
		HashMap<String, NodeWorker> nodemap = new HashMap<String, NodeWorker>();
		// 根节点
		NodeWorker root = null;
		// 根据结果集构造节点列表（存入散列表）
		for (Iterator<NodeWorker> it = list.iterator(); it.hasNext();) {
			NodeWorker node = it.next();
			nodemap.put(node.getId(), node);
		}
		// 构造无序的多叉树
		Set<Entry<String, NodeWorker>> entrySet = nodemap.entrySet();
		for (Iterator<Entry<String, NodeWorker>> it = entrySet.iterator(); it.hasNext();) {
			NodeWorker node = it.next().getValue();
			if (node.getPid() == null || node.getPid().equals("")) {
				root = node;
			} else {
				nodemap.get(node.getPid()).addChild(node);
			}
		}
		// 输出无序的树形菜单的JSON字符串
		return root.toString();
	}


	public static void main(String[] args) {
		// 读取层次数据结果集列表
		List<NodeWorker> dataList = new ArrayList<NodeWorker>();

		NodeWorker dataNode1 = new NodeWorker();
		dataNode1.setId("1030000");
		Node2 n2=new Node2();
		n2.setText("北京软件解放道支部");
		n2.setContent("1030000");
		dataNode1.setData(n2);
		dataNode1.setPid("100000");

		NodeWorker dataNode2 = new NodeWorker();
		dataNode2.setId("1200000");
		Node2 n1=new Node2();
		n1.setText("北京软件三大街支部");
		n1.setContent("1200000");
		dataNode2.setData(n1);
		dataNode2.setPid("100000");
		
		NodeWorker dataNode3 = new NodeWorker();
		dataNode3.setId("112100");
		Node2 n4=new Node2();
		n4.setText("北京软件三大街支部4");
		n4.setContent("12000004");
		dataNode3.setData(n4);
		dataNode3.setPid("1200000");
//
//		Node dataNode4 = new Node();
//		dataNode4.id="113000";
//		dataNode4.text="北京软件开发区支部";
//		dataNode4.parentId="110000";

		NodeWorker dataNode5 = new NodeWorker();
		dataNode5.setId("100000");
		Node2 n3=new Node2();
		n3.setText("北京软件总部");
		n3.setContent("100000");
		dataNode5.setData(n3);
		dataNode5.setPid("");

		
//		Node dataNode6 = new Node();
//		dataNode6.id="110000";
//		dataNode6.text="北京支部";
//		dataNode6.parentId="100000";
//		
//		Node dataNode7 = new Node();
//		dataNode7.id="111000";
//		dataNode7.text="北京软件金光道支部";
//		dataNode7.parentId="110000";

		
//		HashMap dataNode123 = new HashMap();
//		dataNode123.put("id", "123");
//		dataNode123.put("text", "北京软件开发区支部");
//		dataNode123.put("parentId", "12");

		
		dataList.add(dataNode1);
		dataList.add(dataNode2);
		dataList.add(dataNode5);
		dataList.add(dataNode3);

		MultiTreeBuilder mt = new MultiTreeBuilder();
		System.out.println(mt.generateJson(dataList));

	}

}

/**
 * @author zhangdapeng
 * @version 1.0,2014年5月13日
 * @since 1.0
 */
public class Node2{
	/**
	 * 节点内容
	 */
	private String text;
	
	/**
	 * 节点内容
	 */
	private String content;

	/**
	 * 
	 */
	public Node2() {
		// TODO Auto-generated constructor stub
	}


	public String getText() {
		return text;
	}

	public void setText(String text) {
		this.text = text;
	}


	public String getContent() {
		return content;
	}


	public void setContent(String content) {
		this.content = content;
	}

}

这是返回结果：

{
	"text": "北京软件总部",
	"content": "100000",
	"c": [{
		"text": "北京软件三大街支部",
		"content": "1200000",
		"c": [{
			"text": "北京软件三大街支部4",
			"content": "12000004"
		}]
	},
	{
		"text": "北京软件解放道支部",
		"content": "1030000"
	}]
}