在做Extjs开发时，经常用到tree的json数据格式，但网上一些转换工具过于简单，例如要一个比较复杂的columntree，简单的treejson就不能解决了。

我在实际过程中，利用DefaultMutableTreeNode处理了Tree。仅供网友参考。。。

共需要两个类文件，TreeNode，JsonUtil。

原理：将需要显示在树的内容，抽象成为一个类文件，作为TreeNode的userObject属性。

类TreeNode

 /* * 文件包:com.clc.pub * 文件名称 : JsonTreeNode.java * 创建日期： Oct 12, 2009 * 创建人： Y.W.Zhang */ package com.clc.pub.string.json; import java.util.Enumeration; import javax.swing.tree.DefaultMutableTreeNode; /** * <p>标题:JsonTreeNode.java</p> * <p>描述: </p> * <p></p> * <p>国银金融租赁有限公司</p> * @author Y.W.Zhang * @version 1.0 * */ public class TreeNode extends DefaultMutableTreeNode{ private String id; private String name; /** * 构建一个<code>JsonTreeNode</code> 对象. */ public TreeNode() { this.id="root"; this.name="root"; this.setUserObject(new Object()); } public TreeNode(String _id,String _name) { this.id=_id; this.name=_name; } /** * @return id */ public String getId() { return this.id; } /** * @param id to set */ public void setId(String id) { this.id = id; } /** * @return name */ public String getName() { return this.name; } /** * @param name to set */ public void setName(String name) { this.name = name; } /** * 递归函数，重组字符串，注释部分为根据不同的前台数据进行个性处理。 * @param sb * @param node */ private void RebuildJsonString(StringBuffer sb,TreeNode node) { if (node.isLeaf()) { String temp=JsonUtil.bean2json(node.getUserObject()); temp=temp.substring(1, temp.length()-1); sb.append("{"); sb.append(temp); sb.append(",\"uiProvider\":\"col\",\"leaf\":\"true\""); //sb.append(",\"parent\":\"").append(((TreeNode)node.getParent()).getId()).append("\""); sb.append("}"); } else { Enumeration<?> childrenEnum = node.children(); String temp=JsonUtil.bean2json(node.getUserObject()); temp=temp.substring(1, temp.length()-1); sb.append("{"); sb.append(temp); // if(node.getParent()!=null) { // sb.append(",\"parent\":\"").append(((TreeNode)node.getParent()).getId()).append("\""); // } sb.append(",\"uiProvider\":\"col\",\"children\":["); while (childrenEnum.hasMoreElements()) { TreeNode child = (TreeNode) childrenEnum.nextElement(); RebuildJsonString(sb,child); sb.append(","); } sb.append("]}"); sb.delete(sb.length()-3, sb.length()-2); } } public String toJsonString() { StringBuffer sb=new StringBuffer(); sb.append("["); this.RebuildJsonString(sb,(TreeNode)this.getRoot()); sb.delete(sb.length()-1, sb.length()); sb.append("}]"); String temp=sb.toString(); int x=temp.indexOf("children"); temp=temp.substring(x+10); temp=temp.substring(0,temp.length()-2); return temp; } }

JsonUtil 好心人提供的

package com.clc.pub.string.json; import java.beans.IntrospectionException; import java.beans.Introspector; import java.beans.PropertyDescriptor; import java.math.BigDecimal; import java.math.BigInteger; import java.util.List; import java.util.Map; import java.util.Set; public class JsonUtil { public static String object2json(Object obj) { StringBuilder json = new StringBuilder(); if (obj == null) { json.append("\"\""); } else if (obj instanceof String || obj instanceof Integer || obj instanceof Float || obj instanceof Boolean || obj instanceof Short || obj instanceof Double || obj instanceof Long || obj instanceof BigDecimal || obj instanceof BigInteger || obj instanceof Byte) { json.append("\"").append(string2json(obj.toString())).append("\""); } else if (obj instanceof Object[]) { json.append(array2json((Object[]) obj)); } else if (obj instanceof List) { json.append(list2json((List<?>) obj)); } else if (obj instanceof Map) { json.append(map2json((Map<?, ?>) obj)); } else if (obj instanceof Set) { json.append(set2json((Set<?>) obj)); } else { json.append(bean2json(obj)); } return json.toString(); } public static String bean2json(Object bean) { StringBuilder json = new StringBuilder(); json.append("{"); PropertyDescriptor[] props = null; try { props = Introspector.getBeanInfo(bean.getClass(), Object.class).getPropertyDescriptors(); } catch (IntrospectionException e) { } if (props != null) { for (int i = 0; i < props.length; i++) { try { String name = object2json(props[i].getName()); String value = object2json(props[i].getReadMethod().invoke(bean)); json.append(name); json.append(":"); json.append(value); json.append(","); } catch (Exception e) { } } json.setCharAt(json.length() - 1, '}'); } else { json.append("}"); } return json.toString(); } public static String list2json(List<?> list) { StringBuilder json = new StringBuilder(); json.append("["); if (list != null && list.size() > 0) { for (Object obj : list) { json.append(object2json(obj)); json.append(","); } json.setCharAt(json.length() - 1, ']'); } else { json.append("]"); } return json.toString(); } public static String array2json(Object[] array) { StringBuilder json = new StringBuilder(); json.append("["); if (array != null && array.length > 0) { for (Object obj : array) { json.append(object2json(obj)); json.append(","); } json.setCharAt(json.length() - 1, ']'); } else { json.append("]"); } return json.toString(); } public static String map2json(Map<?, ?> map) { StringBuilder json = new StringBuilder(); json.append("{"); if (map != null && map.size() > 0) { for (Object key : map.keySet()) { json.append(object2json(key)); json.append(":"); json.append(object2json(map.get(key))); json.append(","); } json.setCharAt(json.length() - 1, '}'); } else { json.append("}"); } return json.toString(); } public static String set2json(Set<?> set) { StringBuilder json = new StringBuilder(); json.append("["); if (set != null && set.size() > 0) { for (Object obj : set) { json.append(object2json(obj)); json.append(","); } json.setCharAt(json.length() - 1, ']'); } else { json.append("]"); } return json.toString(); } public static String string2json(String s) { if (s == null) return ""; StringBuilder sb = new StringBuilder(); for (int i = 0; i < s.length(); i++) { char ch = s.charAt(i); switch (ch) { case '"': sb.append("\\\""); break; case '\\': sb.append("\\\\"); break; case '\b': sb.append("\\b"); break; case '\f': sb.append("\\f"); break; case '\n': sb.append("\\n"); break; case '\r': sb.append("\\r"); break; case '\t': sb.append("\\t"); break; case '/': sb.append("\\/"); break; default: if (ch >= '\u0000' && ch <= '\u001F') { String ss = Integer.toHexString(ch); sb.append("\\u"); for (int k = 0; k < 4 - ss.length(); k++) { sb.append('0'); } sb.append(ss.toUpperCase()); } else { sb.append(ch); } } } return sb.toString(); } }

例子：

建一个对象类

public class A {

。。。。。

}

public static void main(String[]args) { A a1=new A(1,"1"); A a2=new A(2,"2"); A a3=new A(3,"3"); A a4=new A(4,"4"); A a5=new A(5,"5"); A a6=new A(6,"6"); TreeNode node1=new TreeNode("1","1"); node1.setUserObject(a1); TreeNode node2=new TreeNode("2","2"); node2.setUserObject(a2); TreeNode node3=new TreeNode("3","3"); node3.setUserObject(a3); TreeNode node4=new TreeNode("4","4"); node4.setUserObject(a4); TreeNode node5=new TreeNode("5","5"); node5.setUserObject(a5); TreeNode node6=new TreeNode("6","6"); node6.setUserObject(a6); TreeNode root=new TreeNode(); //root.setUserObject(a1); root.add(node1); root.add(node2); node1.add(node3); node2.add(node4); //node4.add(node5); //node5.add(node6); System.out.println(root.toJsonString()); }

[{"id":"1","name":"1","uiProvider":"col","children":[{"id":"3","name":"3","uiProvider":"col","leaf":"true"}]},{"id":"2","name":"2","uiProvider":"col","children":[{"id":"4","name":"4","uiProvider":"col","leaf":"true"}]}]

• JSON