JSP表格模板升级-- 用Java反射动态指定方法和参数 .
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本文中笔者将对该模板进行升级,使得客户端可以动态指定调用业务类的哪个方法,并给出不同的方法参数。要实现动态调用,自然想到的就是反射:
- Method method = reportF.getClass().getMethod(methodname,String.class);
- list = (List<KeyValueBean>)method.invoke(reportF,param);
Method method = reportF.getClass().getMethod(methodname,String.class);list = (List<KeyValueBean>)method.invoke(reportF,param);
Java反射的基础知识笔者也是现学现卖的,就不在本文赘述了,这里的methodname是前端调用者动态指定的方法名,因此第一行代码调用getMethod,获取了ReportFunctions类的一个方法的Method对象,这个方法接收一个字符串类型的参数。第二行代码用前端调用者指定的参数param作为方法参数,来触发这个方法,返回一个KeyValueBean数组。这样,我们就可以根据前端调用者提供的methodname和param,来调用任意拥有一个字符串类型参数的方法了。
有了这个思路,当我们需要在前端指定调用参数个数不同的方法时,只需在jsp的逻辑代码中进行相应的判断、处理即可,核心代码如下所示:
- if(methodname.equals("deptCategoryByZoneid") ||
- methodname.equals("elevMonitorByZoneid") ||
- methodname.equals("elevTestStatusByzoneid")) {
- method = reportF.getClass().getMethod(methodname,String.class);
- list = (List<KeyValueBean>)method.invoke(reportF,zoneid);
- }else if(methodname.equals("elevAlarmOverview") ||
- methodname.equals("maintenanceTimelyCategory") ||
- methodname.equals("maintenanceTimeQualify")) {
- method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class);
- list = (List<KeyValueBean>)method.invoke(reportF,zoneid,dateFrom,dateTo);
- }else {
- method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class,String.class,String.class);
- list = (List<KeyValueBean>)method.invoke(reportF,deptProperty,zoneid,dateFrom,dateTo,deptNum);
- }
if(methodname.equals("deptCategoryByZoneid") ||methodname.equals("elevMonitorByZoneid") ||methodname.equals("elevTestStatusByzoneid")) {method = reportF.getClass().getMethod(methodname,String.class);list = (List<KeyValueBean>)method.invoke(reportF,zoneid);}else if(methodname.equals("elevAlarmOverview") ||methodname.equals("maintenanceTimelyCategory") ||methodname.equals("maintenanceTimeQualify")) {method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class);list = (List<KeyValueBean>)method.invoke(reportF,zoneid,dateFrom,dateTo);}else {method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class,String.class,String.class);list = (List<KeyValueBean>)method.invoke(reportF,deptProperty,zoneid,dateFrom,dateTo,deptNum);}其中deptProperty、zoneid、dataFrom、dataTo等参数都是jsp的调用者提供的,不同的方法使用不同的参数。可能存在其它更具复用性、更优雅的写法,笔者有时间的时候再去研究。模板的完整代码如下:
- <%@ page language="java" contentType="text/html; charset=UTF-8"
- pageEncoding="UTF-8"%>
- <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
- <%@ page import="com.reports.util.ReportFunctions"%>
- <%@ page import="com.reports.util.SpringContextHolder" %>
- <%@ page import="com.reports.charts.bean.KeyValueBean"%>
- <%@ page import="java.lang.reflect.Method" %>
- <%@ page import="java.util.*" %>
- <%
- String methodname = request.getParameter("method");
- String zoneid = request.getParameter("zoneid");
- if(zoneid==null) {
- zoneid="000000";
- }
- String dateFrom = request.getParameter("dateFrom");
- String dateTo = request.getParameter("dateTo");
- String categories = request.getParameter("categories");
- String deptProperty = request.getParameter("deptProperty");
- String deptCode = request.getParameter("deptCode");
- String deptNum = request.getParameter("deptNum");
- String sort = request.getParameter("sort");
- ReportFunctions reportF = SpringContextHolder.getBean(ReportFunctions.class);
- Method method = null;
- List<KeyValueBean> list = null;
- if(methodname.equals("deptCategoryByZoneid") ||
- methodname.equals("elevMonitorByZoneid") ||
- methodname.equals("elevTestStatusByzoneid")) {
- method = reportF.getClass().getMethod(methodname,String.class);
- list = (List<KeyValueBean>)method.invoke(reportF,zoneid);
- }else if(methodname.equals("elevAlarmOverview") ||
- methodname.equals("maintenanceTimelyCategory") ||
- methodname.equals("maintenanceTimeQualify")) {
- method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class);
- list = (List<KeyValueBean>)method.invoke(reportF,zoneid,dateFrom,dateTo);
- }else if(methodname.equals("elevAlarmRateByDept")) {
- method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class,String.class,String.class);
- list = (List<KeyValueBean>)method.invoke(reportF,deptProperty,zoneid,dateFrom,dateTo,deptNum);
- }else if(methodname.equals("elevAlarmByDept")) {
- method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class,String.class,String.class);
- list = (List<KeyValueBean>)method.invoke(reportF,zoneid,dateFrom,dateTo,deptProperty,deptCode);
- }else if(methodname.equals("elevMultiCategoryForTable")) {
- List<String> lc = new ArrayList<String>();
- String[] ac = categories.split(",");
- for(int i=0; i<ac.length; i++) {
- lc.add(ac[i]);
- }
- method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class,List.class);
- list = (List<KeyValueBean>)method.invoke(reportF,zoneid,dateFrom,dateTo,lc);
- }
- request.setAttribute("list", list);
- %>
- <table id="tb_departCate" style="border-color: #fff">
- <tr bgcolor="#4F81BD" style="color: #fff;">
- <th style="text-align: center">${list[0].key}</th>
- <c:forEach items="${list[0].value}" var="ch">
- <th style="text-align: center">${ch}</th>
- </c:forEach>
- </tr>
- <c:forEach items="${list}" var="row" varStatus="status" begin="1">
- <tr bgcolor="${status.index%2 == 0?'#D0D8E8':'#E9EDF4'}">
- <td align="center">${row.key}</td>
- <c:forEach items="${row.value}" var="col">
- <td align="center">${col}</td>
- </c:forEach>
- </tr>
- </c:forEach>
- </table>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><%@ page import="com.reports.util.ReportFunctions"%><%@ page import="com.reports.util.SpringContextHolder" %><%@ page import="com.reports.charts.bean.KeyValueBean"%><%@ page import="java.lang.reflect.Method" %><%@ page import="java.util.*" %><%String methodname = request.getParameter("method");String zoneid = request.getParameter("zoneid");if(zoneid==null) {zoneid="000000";}String dateFrom = request.getParameter("dateFrom");String dateTo = request.getParameter("dateTo");String categories = request.getParameter("categories");String deptProperty = request.getParameter("deptProperty");String deptCode = request.getParameter("deptCode");String deptNum = request.getParameter("deptNum");String sort = request.getParameter("sort");ReportFunctions reportF = SpringContextHolder.getBean(ReportFunctions.class);Method method = null;List<KeyValueBean> list = null;if(methodname.equals("deptCategoryByZoneid") ||methodname.equals("elevMonitorByZoneid") ||methodname.equals("elevTestStatusByzoneid")) {method = reportF.getClass().getMethod(methodname,String.class);list = (List<KeyValueBean>)method.invoke(reportF,zoneid);}else if(methodname.equals("elevAlarmOverview") ||methodname.equals("maintenanceTimelyCategory") ||methodname.equals("maintenanceTimeQualify")) {method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class);list = (List<KeyValueBean>)method.invoke(reportF,zoneid,dateFrom,dateTo);}else if(methodname.equals("elevAlarmRateByDept")) {method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class,String.class,String.class);list = (List<KeyValueBean>)method.invoke(reportF,deptProperty,zoneid,dateFrom,dateTo,deptNum);}else if(methodname.equals("elevAlarmByDept")) {method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class,String.class,String.class);list = (List<KeyValueBean>)method.invoke(reportF,zoneid,dateFrom,dateTo,deptProperty,deptCode);}else if(methodname.equals("elevMultiCategoryForTable")) {List<String> lc = new ArrayList<String>();String[] ac = categories.split(",");for(int i=0; i<ac.length; i++) {lc.add(ac[i]);}method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class,List.class);list = (List<KeyValueBean>)method.invoke(reportF,zoneid,dateFrom,dateTo,lc);}request.setAttribute("list", list);%><table id="tb_departCate" style="border-color: #fff"><tr bgcolor="#4F81BD" style="color: #fff;"><th style="text-align: center">${list[0].key}</th><c:forEach items="${list[0].value}" var="ch"><th style="text-align: center">${ch}</th></c:forEach></tr><c:forEach items="${list}" var="row" varStatus="status" begin="1"><tr bgcolor="${status.index%2 == 0?'#D0D8E8':'#E9EDF4'}"><td align="center">${row.key}</td><c:forEach items="${row.value}" var="col"><td align="center">${col}</td></c:forEach></tr></c:forEach></table>
模板的使用方法同上文《用JSP创建一个表格模板》类似。假定我们将上述文件保存为_tb2ColParam.jsp,则我们可以通过类似“_tb2ColParam.jsp?method=maintenanceStatus&zoneid=320200&dateFrom=2013&dateTo=2013”这样的形式来访问该jsp模板,也就是调用后台某业务类的maintenanceStatus方法,使用zoneid、dateFrom、dateTo三个参数生成一张表格。
上文发表之后,有人问到为什么要用jsp来生成表格而不是在前端,以及传参的问题。关于前一个问题,前端生成还是后端生成这是两个不同的概念,后端能做的事还是交给后端来做吧,后端生成这种静态的、样式简单的表格速度比前端快不止一个数量级。关于传参的问题,笔者会在下一篇文章中详细说明多种方式。
-------------------------------------------
package com.lifei.etool.reflexology;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class ReportFunctions {
public List deptCategoryByZoneid(String str) {
List list = new ArrayList();
Map<String, String> map=new HashMap<String, String>();
map.put("key", "deptCategoryByZoneid");
list.add(map);
System.out.println("deptCategoryByZoneid-------------");
return list;
}
public List elevAlarmOverview(String str) {
List list = new ArrayList();
list.add("elevAlarmOverview");
System.out.println("elevAlarmOverview-------------");
return list;
}
}
----------------------------------------------
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@page import="com.lifei.etool.reflexology.ReportFunctions" %>
<%@ page import="java.lang.reflect.Method" %>
<%@ page import="java.util.*" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<%
String methodname = request.getParameter("method");
String zoneid = request.getParameter("zoneid");
if(zoneid==null) {
zoneid="000000";
}
zoneid="zoneid";
methodname="deptCategoryByZoneid";
String dateFrom = request.getParameter("dateFrom");
String dateTo = request.getParameter("dateTo");
String categories = request.getParameter("categories");
String deptProperty = request.getParameter("deptProperty");
String deptCode = request.getParameter("deptCode");
String deptNum = request.getParameter("deptNum");
String sort = request.getParameter("sort");
/* ReportFunctions reportF = SpringContextHolder.getBean(ReportFunctions.class); */
ReportFunctions reportF=new ReportFunctions();
Method method = null;
List list = null;
if(methodname=="deptCategoryByZoneid" ||
methodname=="elevMonitorByZoneid" ||
methodname=="elevTestStatusByzoneid") {
method = reportF.getClass().getMethod(methodname,String.class);
list = (List)method.invoke(reportF,zoneid);
}else if(methodname=="elevAlarmOverview" ||
methodname=="maintenanceTimelyCategory" ||
methodname=="maintenanceTimeQualify") {
method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class);
list = (List)method.invoke(reportF,zoneid,dateFrom,dateTo);
}else if(methodname=="elevAlarmRateByDept") {
method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class,String.class,String.class);
list = (List)method.invoke(reportF,deptProperty,zoneid,dateFrom,dateTo,deptNum);
}else if(methodname=="elevAlarmByDept") {
method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class,String.class,String.class);
list = (List)method.invoke(reportF,zoneid,dateFrom,dateTo,deptProperty,deptCode);
}else if(methodname=="elevMultiCategoryForTable") {
List<String> lc = new ArrayList<String>();
String[] ac = categories.split(",");
for(int i=0; i<ac.length; i++) {
lc.add(ac[i]);
}
method = reportF.getClass().getMethod(methodname,String.class,String.class,String.class,List.class);
list = (List)method.invoke(reportF,zoneid,dateFrom,dateTo,lc);
}
request.setAttribute("list", list);
out.println(list);
%>
<table id="tb_departCate" style="border-color: #fff">
<tr bgcolor="#4F81BD" style="color: #fff;">
<th style="text-align: center">${list[0].key}</th>
<c:forEach items="${list[0].value}" var="ch">
<th style="text-align: center">${ch}</th>
</c:forEach>
</tr>
<c:forEach items="${list}" var="row" varStatus="status" begin="1">
<tr bgcolor="${status.index%2 == 0?'#D0D8E8':'#E9EDF4'}">
<td align="center">${row.key}</td>
<c:forEach items="${row.value}" var="col">
<td align="center">${col}</td>
</c:forEach>
</tr>
</c:forEach>
</table>
</body>
</html>
-----------------------------------------------------------
- JSP表格模板升级(1)-- 用Java反射动态指定方法和参数
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