LookupDispatchAction类

最新推荐文章于 2025-07-22 19:53:31 发布

zerolsy

最新推荐文章于 2025-07-22 19:53:31 发布

阅读量1.3k

点赞数

CC 4.0 BY-SA版权

文章标签： session html action struts hashmap input

本文链接：https://blog.youkuaiyun.com/zerolsy/article/details/2582328

LookupDispatchAction类

它是DispatchAction类的子类,也可以定义多种业务方法，它是利用请求参数值,反向查询资源并将它与类中的一种方法匹配。通常用于有多个同名提交按钮的表单的场合。它的处理更加简单。

该Action也可包含多个处理方法，它可让处理方法与按钮直接关联，无须使用任何的脚本。使用LookupDispatchAction时，提交按钮必须使用Struts 的html 标签.

LookupDispatchAction类使用：

1 必须用struts的html标签

2 必须实现LookupDispatchAction类的protected Map getKeyMethodMap()方法，即将这个类中的业务处理方法绑定到相关按钮上！

3 struts.config.xml中parameter="method"要与<html:submit property="method">中的属性值相同。

<action

attribute="calcForm"

input="/input.jsp"

name="calcForm"

path="/calc"

scope="request"

parameter="method"

type="cn.action.CalcAction">

</action>

这段配置代码表明:该action根据method 参数来区分请求分别调用哪个方法，此时无须使用method 的隐藏域，而是将按钮的property 设为method。通过这种方式可以避免书写javascript脚本。

例子：用LookupDispatchAction实现四则运算

Input.jsp 代码：

<%@ page language="java" pageEncoding="gb18030"%>

<%@ taglib uri="http://jakarta.apache.org/struts/tags-bean" prefix="bean"%>

<%@ taglib uri="http://jakarta.apache.org/struts/tags-html" prefix="html"%>

<html>

<head>

<title>LookupDispatchAction</title>

</head>

<body>

<html:form action="calc" method="post">

第一个数 : <html:text property="num1"/><html:errors property="error1"/><br/>

第二个数 : <html:text property="num2"/><html:errors property="error2"/><br/>

<html:submit property="method"><bean:message key="operate.add"/></html:submit>

<html:submit property="method"><bean:message key="operate.subtract"/></html:submit>

<html:submit property="method"><bean:message key="operate.multiply"/></html:submit>

<html:submit property="method"><bean:message key="operate.divide"/></html:submit>

<html:reset property="reset"><bean:message key="operate.clear"/></html:reset>

</html:form>

</body>

</html>

CalcAction.java 代码：

package cn.action;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import org.apache.struts.action.ActionForm;

import org.apache.struts.action.ActionForward;

import org.apache.struts.action.ActionMapping;

import org.apache.struts.action.ActionMessage;

import org.apache.struts.action.ActionMessages;

import org.apache.struts.actions.LookupDispatchAction;

import cn.form.CalcForm;

import java.util.HashMap;

import java.util.Map;

/**

*MyEclipseStruts

*Creationdate:03-23-2008

*XDocletdefinition:

*@struts.actionpath="/calc"name="calcForm"input="/input.jsp"scope="request"validate="true"

publicclass CalcAction extends LookupDispatchAction {

//实现getKeyMethodMap()方法

//从map对象中查找与按钮名称对应的方法

//将方法绑定到按钮上

protected Map getKeyMethodMap(){

Map map=new HashMap();

map.put("operate.add","doAdd");

map.put("operate.subtract","doSubtract");

map.put("operate.multiply","doMultiply");

map.put("operate.divide","doDivide");

return map;

}

privateintnum1=0;

privateintnum2=0;

//加

public ActionForward doAdd(ActionMapping mapping, ActionForm form,

HttpServletRequest request, HttpServletResponse response) {

CalcForm calcForm = (CalcForm) form;// TODO Auto-generated method stub

//ActionMessages errors=new ActionMessages();

HttpSession session=request.getSession();

session=request.getSession();

num1=Integer.parseInt(calcForm.getNum1());

num2=Integer.parseInt(calcForm.getNum2());

session.setAttribute("result", Integer.valueOf((num1+num2)));

return mapping.findForward("result");

}

//减

public ActionForward doSubtract(ActionMapping mapping, ActionForm form,

HttpServletRequest request, HttpServletResponse response) {

CalcForm calcForm = (CalcForm) form;// TODO Auto-generated method stub

HttpSession session=request.getSession();

session=request.getSession();

num1=Integer.parseInt(calcForm.getNum1());

num2=Integer.parseInt(calcForm.getNum2());

session.setAttribute("result", Integer.valueOf((num1-num2)));

return mapping.findForward("result");

}

//乘

public ActionForward doMultiply(ActionMapping mapping, ActionForm form,

HttpServletRequest request, HttpServletResponse response) {

CalcForm calcForm = (CalcForm) form;// TODO Auto-generated method stub

HttpSession session=request.getSession();

session=request.getSession();

num1=Integer.parseInt(calcForm.getNum1());

num2=Integer.parseInt(calcForm.getNum2());

session.setAttribute("result", Integer.valueOf((num1*num2)));

return mapping.findForward("result");

}

//除

public ActionForward doDivide(ActionMapping mapping, ActionForm form,

HttpServletRequest request, HttpServletResponse response) {

CalcForm calcForm = (CalcForm) form;// TODO Auto-generated method stub

ActionMessages errors=calcForm.validate(mapping, request);

if(Integer.parseInt(calcForm.getNum2())==0){

errors.add("error2", new ActionMessage("errors.validate.zero"));

super.saveErrors(request, errors);//调用ActionForm方法保存这个错误信息

return mapping.findForward("input");

}

HttpSession session=request.getSession();

session=request.getSession();

num1=Integer.parseInt(calcForm.getNum1());

num2=Integer.parseInt(calcForm.getNum2());

session.setAttribute("result", Integer.valueOf((num1/num2)));

return mapping.findForward("result");

}