自定义标签+反射
说明：为了使用dhtmlx的Tree控件，动态生成所需的xml文件，通过一个父子关系的节点拼出来。
import java.io.IOException;import java.lang.reflect.Method;import java.util.List;import java.util.logging.Level;import java.util.logging.Logger;import javax.servlet.jsp.JspException;import javax.servlet.jsp.JspWriter;import javax.servlet.jsp.tagext.TagSupport;import org.apache.commons.lang.StringUtils;/** * * @author gby */public class XMLForTreeTag extends TagSupport { private Object rootNode; private String nodeIdProperty; private String nodeTypeProperty; private String nodeTitleProperty; private String childCollectionProperty; /** * * @return int * @throws JspException */ @Override public int doStartTag() throws JspException { StringBuffer sb = new StringBuffer(); try { sb = toHTML(rootNode, nodeIdProperty, nodeTitleProperty, nodeTypeProperty, childCollectionProperty); } catch (Exception ex) { Logger.getLogger(XMLForTreeTag.class.getName()).log(Level.SEVERE, null, ex); } JspWriter out = pageContext.getOut(); try { out.println(sb.toString()); } catch (IOException e) { e.printStackTrace(); } return SKIP_BODY; } /** * <tree id="0" > <item text="name1" id="id1"> <item text="name1-1" id="id1-1"> </item> </item> </tree> * @param rootNode * @param nodeIdProperty * @param nodeTitleProperty * @param nodeTypeProperty * @param childCollectionProperty * @return * @throws Exception */ public StringBuffer toHTML(Object rootNode, String nodeIdProperty, String nodeTitleProperty, String nodeTypeProperty, String childCollectionProperty) throws Exception { StringBuffer sb = new StringBuffer(); sb.append("<tree id=\"0\">\n"); String nodes = this.createXML(rootNode, nodeIdProperty, nodeTitleProperty, nodeTypeProperty, childCollectionProperty, sb); sb.append("</tree>\n"); return sb; } private String createXML(Object node, String nodeIdProperty, String nodeTitleProperty, String nodeTypeProperty, String childCollectionProperty, StringBuffer sb) throws Exception { Class<?> clazz = node.getClass(); //获得属性的get方法名。 String nodeIdMethodName = this.createMethodName(nodeIdProperty); String nodeTitleMethodName = this.createMethodName(nodeTitleProperty); String nodeTypeMethodName = this.createMethodName(nodeTypeProperty); String childCollectionMethodName = this.createMethodName(childCollectionProperty); //根据反射获得method Method nodeIdMethod = clazz.getMethod(nodeIdMethodName, new Class[0]); Method nodeTitleMethod = clazz.getMethod(nodeTitleMethodName, new Class[0]); Method nodeTypeMethod = clazz.getMethod(nodeTypeMethodName, new Class[0]); Method childCollectionMethod = clazz.getMethod(childCollectionMethodName, new Class[0]); if (node != null) { String nodeId = (String) nodeIdMethod.invoke(node, new Object[0]); String nodeTitle = (String) nodeTitleMethod.invoke(node, new Object[0]); String nodeType = (String) nodeTypeMethod.invoke(node, new Object[0]); String itemId = nodeId + "__" + nodeType; sb.append("<item text=\"").append(nodeTitle).append("\" ") .append(" id=\"").append(itemId).append("\">"); List children = (List) childCollectionMethod.invoke(node, new Object[0]); if (children != null && !children.isEmpty()) { for (Object child : children) { this.createXML(child, nodeIdProperty, nodeTitleProperty, nodeTypeProperty, childCollectionProperty, sb); } } sb.append("</item>\n"); } return sb.toString(); } private String createMethodName(String property) { if (StringUtils.isEmpty(property)) { return null; } String method = "get" + property.substring(0, 1).toUpperCase() + property.substring(1); return method; } getters().. setters()..}
tld文件(TldName.tld)

<?xml version="1.0" encoding="UTF-8"?><!-- edited with XML Spy v4.3 U (http://www.xmlspy.com) by LEGO (LEGO) --><!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN" "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd"><taglib>    <tag>        <name>xmlForTree</name>        <tagclass>XMLForTreeTag</tagclass>        <info>为显示多选树形拼的XML-dhtmlx</info>        <attribute>            <name>rootNode</name>            <required>true</required>            <rtexprvalue>true</rtexprvalue>        </attribute>        <attribute>            <name>nodeIdProperty</name>            <required>true</required>            <rtexprvalue>true</rtexprvalue>        </attribute>        <attribute>            <name>nodeTypeProperty</name>            <required>true</required>            <rtexprvalue>true</rtexprvalue>        </attribute>        <attribute>            <name>nodeTitleProperty</name>            <required>true</required>            <rtexprvalue>true</rtexprvalue>        </attribute>        <attribute>            <name>childCollectionProperty</name>            <required>true</required>            <rtexprvalue>true</rtexprvalue>        </attribute>    </tag></taglib>

import java.io.Serializable;import java.util.List;/** * 树形显示DTO * @author gby */public class NodeDTO implements Serializable{    /**     * node的唯一标识     */    private String id;    /**     * node的唯一标识     */    private String parentId;    /**     * node的名称     */    private String name;    /**     * node的父节点     */    private NodeDTO parentDTO;    /**     * node的孩子节点     */    private List<NodeDTO> childrenDTO;    //节点类型    private String nodeType;    getters().. setters()..}