在jsp中使用自定义标签 实现反射机制

其中存在两张表A和B，其中表B中字段的值是表A的某个字段，现在给你B中某字段的值和对象A，要你取出它在对象A中对应的属性值。在这种情况下你若选择使用反射机制会非常方面。一下是相应的代码：

import java.io.IOException;import java.lang.reflect.Field;import javax.servlet.jsp.JspException;import javax.servlet.jsp.JspWriter;import javax.servlet.jsp.tagext.TagSupport;public class RFTag extends TagSupport {private static final long serialVersionUID = -2360561035810220875L;private Object object;private String property;public Object getObject() {return object;}public void setObject(Object object) {this.object = object;}public String getProperty() {return property;}public void setProperty(String property) {this.property = property;}public int doStartTag() throws JspException {JspWriter out = this.pageContext.getOut();try {if (object == null) {out.println("");} else {//get the object of this fieldField f = object.getClass().getDeclaredField(property);f.setAccessible(true);//get the value of this fieldObject value = f.get(object);out.println(value == null ? "" : value.toString());}} catch (IOException e) {e.printStackTrace();} catch (IllegalArgumentException e) {e.printStackTrace();} catch (SecurityException e) {e.printStackTrace();} catch (NoSuchFieldException e) {e.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();}return SKIP_BODY;}}

下面是WEB-INF目录下的文件fs.tld文件的内容，主要是定义的在jsp中使用的标签。代码如下：

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN" "web-jsptaglibrary_1_2.dtd" ><taglib>  <tlib-version>1.0</tlib-version>  <jsp-version>2.0</jsp-version>  <short-name>foundTag</short-name>  <uri>http://www.foundersoftware.com/founder/tags</uri>  <tag>    <name>page</name>    <tag-class>com.founder.abgent.core.web.tag.PageTag</tag-class>    <attribute>  <name>action</name>  <required>true</required>  <rtexprvalue>true</rtexprvalue>  </attribute>   <attribute>  <name>param</name>  <required>false</required>  <rtexprvalue>true</rtexprvalue>  </attribute>    <attribute>  <name>color</name>  <required>false</required>  </attribute>  </tag>    <tag>  <name>rf</name>  <tag-class>com.founder.bcimp.core.web.tag.RFTag</tag-class>  <attribute>  <name>object</name>  <required>true</required>  <rtexprvalue>true</rtexprvalue>  </attribute>  <attribute>  <name>property</name>  <required>true</required>  <rtexprvalue>true</rtexprvalue>  </attribute>  </tag></taglib>

具体的在jsp中的应用实例.代码如下：

<%@ page language="java" contentType="text/html; charset=UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%><%@ taglib uri="http://www.foundersoftware.com/founder/tags" prefix="fs"%><div><c:if test="${not empty enterpriseCustomFieldList}"><table><tr><td colspan="2"><fmt:message key="crs.compound.enterprise.custom.field" /></td></tr><c:forEach items="${enterpriseCustomFieldList}" var="enterpriseCustomField"><tr><th>${enterpriseCustomField.columnLabel }</th><td><input type="text" name="${enterpriseCustomField.columnName}" maxlength="${enterpriseCustomField.length}" value[b]="<fs:rf object="${compound}" property="${enterpriseCustomField.columnName}" />"/[/b]></td></tr></c:forEach></table></c:if></div>