轉(zhuǎn)載地址 ; http://blog.csdn.net/hejingyuan6/article/details/46723021

上篇博客我們說spring web Flow與業(yè)務(wù)結(jié)合的方式主要有三種，下面我們主要介紹一下第三種的應(yīng)用方式

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3，執(zhí)行到<action-state> 元素

SpringWeb Flow 中的這個(gè) <action-state> 是專為執(zhí)行業(yè)務(wù)邏輯而設(shè)的 state 。如果某個(gè)應(yīng)用的業(yè)務(wù)邏輯代碼既不適合放在transition 中由客戶端來觸發(fā)，也不適合放在 Spring Web Flow 自定義的切入點(diǎn)，那么就可以考慮添加<action-state> 元素專用于該業(yè)務(wù)邏輯的執(zhí)行。更傾向于觸發(fā)某個(gè)事件來執(zhí)行。

action-state 示例：

[html] view plaincopyprint?

<action-state?id="addToCart">??

<evaluate?expression="cart.addItem(productService.getProduct(productId))"/>??

<transition?to="productAdded"/>??

</action-state>??

添加subflow 結(jié)點(diǎn)

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商品列表已經(jīng)實(shí)現(xiàn)了，接下來操作步驟為：

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實(shí)現(xiàn) Cart 和 CartItem 兩個(gè)業(yè)務(wù)類

在 shopping.xml 中添加配置

在 /WEB-INF/flows 目錄下添加 addToCart.xml

在 webflow-config.xml 中添加 addToCart.xml 的位置

修改 viewCart.jsp 頁面

?

具體demo實(shí)現(xiàn)：

?

Cart：

[java] view plaincopyprint?

package?samples.webflow;??

??

import?java.io.Serializable;??

import?java.util.ArrayList;??

import?java.util.HashMap;??

import?java.util.List;??

import?java.util.Map;??

??

//購物車的實(shí)現(xiàn)類??

public?class?Cart?implements?Serializable?{??

??

????private?static?final?long?serialVersionUID?=?7901330827203016310L;??

????private?Map<Integer,?CartItem>?map?=?new?HashMap<Integer,?CartItem>();??

?????

????//getItems?用于獲取當(dāng)前購物車?yán)锏奈锲?/span>??

????public?List<CartItem>?getItems()?{??

????return?new?ArrayList<CartItem>(map.values());??

????}??

??????

????//addItem?用于向購物車添加商品??

????public?void?addItem(Product?product)?{??

????int?id?=?product.getId();??

????CartItem?item?=?map.get(id);??

????if?(item?!=?null)??

????????item.increaseQuantity();??

????else??

????????map.put(id,?new?CartItem(product,?1));??

????}??

??

????//getTotalPrice?用于獲取購物車?yán)锼猩唐返目們r(jià)格??

????public?int?getTotalPrice()?{??

????int?total?=?0;??

????for?(CartItem?item?:?map.values())??

????????total?+=?item.getProduct().getPrice()?*?item.getQuantity();??

????return?total;??

????}??

}??

Cart 是購物車的實(shí)現(xiàn)類，其同樣要實(shí)現(xiàn)Java.io.Serializable 接口，但它沒有像 ProductService 一樣成為由 Spring IoC 容器管理的 Bean，每個(gè)客戶的購物車是不同的，因此不能使用 Spring IoC 容器默認(rèn)的 Singleton 模式。

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CartItem：

[java] view plaincopyprint?

package?samples.webflow;??

??

import?java.io.Serializable;??

??

//購物車中的條目??

public?class?CartItem?implements?Serializable?{??

????private?static?final?long?serialVersionUID?=?8388627124326126637L;??

????private?Product?product;//商品??

????private?int?quantity;//數(shù)量??

??

????public?CartItem(Product?product,?int?quantity)?{??

????this.product?=?product;??

????this.quantity?=?quantity;??

????}??

??

????//計(jì)算該條目的總價(jià)格??

????public?int?getTotalPrice()?{??

????return?this.quantity?*?this.product.getPrice();??

????}??

??

????//增加商品的數(shù)量??

????public?void?increaseQuantity()?{??

????this.quantity++;??

????}??

??

????/**?

?????*?Return?property?product?

?????*/??

????public?Product?getProduct()?{??

????return?product;??

????}??

??

????/**?

?????*?Sets?property?product?

?????*/??

????public?void?setProduct(Product?product)?{??

????this.product?=?product;??

????}??

??

????/**?

?????*?Return?property?quantity?

?????*/??

????public?int?getQuantity()?{??

????return?quantity;??

????}??

??

????/**?

?????*?Sets?property?quantity?

?????*/??

????public?void?setQuantity(int?quantity)?{??

????this.quantity?=?quantity;??

????}??

??

????/*???getter??setter?*/??

??

}??

shopping.xml：

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<?xml?version="1.0"?encoding="UTF-8"?>??

<flow?xmlns="http://www.springframework.org/schema/webflow"??

????xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"??

????xsi:schemaLocation="http://www.springframework.org/schema/webflow??

?http://www.springframework.org/schema/webflow/spring-webflow-2.0.xsd">??

??

????<!--?在?shopping?flow?開始時(shí)必須分配一個(gè)?Cart?對(duì)象，由于要調(diào)用?subflow?，??

????這個(gè)?Cart?對(duì)象應(yīng)存放于?conversationScope?中。??

????同時(shí)要添加一個(gè)?subflow-state?用于執(zhí)行添加商品到購物車的任務(wù)。?-->??

????<!--?mycart為一個(gè)服務(wù)類?-->??

????<var?name="mycart"?class="samples.webflow.Cart"?/>??

????<on-start>??

????????<set?name="conversationScope.cart"?value="mycart"></set>??

????</on-start>??

????<!--?view-state中的view對(duì)應(yīng)jsp文件夾中的jsp頁面，on是觸發(fā)事件，to對(duì)應(yīng)state?id?-->??

????<view-state?id="viewCart"?view="viewCart">??

????????<!--?在進(jìn)入?view?的?render?流程之后，在?view?真正?render出來之前?-->??

????????<on-render>??

????????????<!--?要在?viewCart?頁面中顯示商品，只需在?view-state?元素的?on-render?切入點(diǎn)調(diào)用?productService???

????????????????的?getProducts?方法，并將所得結(jié)果保存到?viewScope?中即可?-->??

????????????<evaluate?expression="productService.getProducts()"?result="viewScope.products"?/>??

????????</on-render>??

????????<transition?on="submit"?to="viewOrder"?/>??

????????<transition?on="addToCart"?to="addProductToCart"?/>??

????</view-state>??

??????

????<subflow-state?id="addProductToCart"?subflow="addToCart">??

????????<transition?on="productAdded"?to="viewCart"?/>??

????</subflow-state>??

??????

????<view-state?id="viewOrder"?view="viewOrder">??

????????<transition?on="confirm"?to="orderConfirmed">??

????????</transition>??

????</view-state>??

????<view-state?id="orderConfirmed"?view="orderConfirmed">??

????????<transition?on="returnToIndex"?to="returnToIndex">??

????????</transition>??

????</view-state>??

??????

????<end-state?id="returnToIndex"?view="externalRedirect:servletRelative:/index.jsp">??

????</end-state>??

</flow>??

在/WEB-INF/flows 目錄下添加 addToCart.xml

subflow-state元素的 subflow 屬性即指明了這個(gè)被調(diào)用的 flow 的 id 為“ addToCart ”，現(xiàn)在就要添加addToCart flow的定義。

addToCart.xml：

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<?xml?version="1.0"?encoding="UTF-8"?>??

<flow?xmlns="http://www.springframework.org/schema/webflow"??

????xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"??

????xsi:schemaLocation="http://www.springframework.org/schema/webflow???

????http://www.springframework.org/schema/webflow/spring-webflow-2.0.xsd">??

??????

????<!--?flow?執(zhí)行之前?，productId這個(gè)字段內(nèi)容從viewCart頁面中獲取-->??

????<on-start>??

????????<set?name="requestScope.productId"?value="requestParameters.productId"?/>??

????</on-start>??

??????

????<!--?addToCart?flow?主要由一個(gè)?action-state?構(gòu)成，完成添加商品到購物車的功能，??

?????addToCart?flow?的實(shí)現(xiàn)需要有輸入?yún)?shù)，即?productId?。??

?????本示例中是通過請(qǐng)求參數(shù)來傳遞，通過?requestParameters?來獲取該數(shù)值。??

?????這里還要注意到?end-state?的?id?為“?productAdded?”，??

?????與?subflow-state?中的?transition元素的on屬性的名稱是對(duì)應(yīng)的。?-->??

??????

????<action-state?id="addToCart">??

????????<evaluate?expression="cart.addItem(productService.getProduct(productId))"?/>??

????????<transition?to="productAdded"?/>??

????</action-state>??

????<end-state?id="productAdded"?/>??

</flow>??

webflow-config.xml 中添加addToCart.xml 的位置

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<?xml?version="1.0"?encoding="utf-8"?>??

<beans?xmlns="http://www.springframework.org/schema/beans"??

????xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"?xmlns:context="http://www.springframework.org/schema/context"??

????xsi:schemaLocation="http://www.springframework.org/schema/beans???

????http://www.springframework.org/schema/beans/spring-beans-2.5.xsd???

????http://www.springframework.org/schema/context???

????http://www.springframework.org/schema/context/spring-context-2.5.xsd">??

????<!--?搜索?samples.webflow?包里的?@Component?注解，并將其部署到容器中?-->??

????<context:component-scan?base-package="samples.webflow"?/>??

????<!--?啟用基于注解的配置?-->??

????<context:annotation-config?/>??

????<import?resource="webmvc-config.xml"?/>??

????<import?resource="webflow-config.xml"?/>??

</beans>??

viewCart.jsp:

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<?xml?version="1.0"?encoding="utf-8"??>??

<%@?taglib?prefix="c"?uri="http://java.sun.com/jsp/jstl/core"%>??

<!DOCTYPE?html?PUBLIC?"-//W3C//DTD?XHTML?1.0?Transitional//EN"???

??"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">??

<html?xmlns="http://www.w3.org/1999/xhtml">??

<head>??

<meta?http-equiv="Content-Type"?content="text/html;?charset=utf-8"?/>??

<title>View?Cart</title>??

</head>??

<body>??

????<h1>View?Cart</h1>??

????<h2>Items?in?Your?Cart</h2>??

????<c:choose>??

????????<c:when?test="${empty?cart.items}">??

????????????<p>Your?cart?is?empty.</p>??

????????</c:when>??

????????<c:otherwise>??

????????????<table?border="1"?cellspacing="0">??

????????????????<tr>??

????????????????????<th>Item</th>??

????????????????????<th>Quantity</th>??

????????????????????<th>Unit?Price</th>??

????????????????????<th>Total</th>??

????????????????</tr>??

??

????????????????<c:forEach?var="item"?items="${cart.items}">??

????????????????????<tr>??

????????????????????????<td>${item.product.description}</td>??

????????????????????????<td>${item.quantity}</td>??

????????????????????????<td>${item.product.price}</td>??

????????????????????????<td>${item.totalPrice}</td>??

????????????????????</tr>??

????????????????</c:forEach>??

??

????????????????<tr>??

????????????????????<td>TOTAL:</td>??

????????????????????<td></td>??

????????????????????<td></td>??

????????????????????<td>${cart.totalPrice}</td>??

????????????????</tr>??

????????????</table>??

????????</c:otherwise>??

????</c:choose>??

??

????<a?href="${flowExecutionUrl}&_eventId=submit">Submit</a>??

????<h2>Products?for?Your?Choice</h2>??

??

????<table>??

????????<c:forEach?var="product"?items="${products}">??

????????????<tr>??

????????????????<td>${product.description}</td>??

????????????????<td>${product.price}</td>??

??

??

????????????????<td><a??

????????????????????href="${flowExecutionUrl}&_eventId=addToCart&productId=${product.id}">[add??

????????????????????????to?cart]</a></td>??

??

??

????????????</tr>??

????????</c:forEach>??

??

????</table>??

</body>??

</html>??

viewOrder.jsp:

[html] view plaincopyprint?

<?xml?version="1.0"?encoding="utf-8"??>??

<%@?taglib?prefix="c"?uri="http://java.sun.com/jsp/jstl/core"%>??

<!DOCTYPE?html?PUBLIC?"-//W3C//DTD?XHTML?1.0?Transitional//EN"???

??"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">??

<html?xmlns="http://www.w3.org/1999/xhtml">??

<head>??

<meta?http-equiv="Content-Type"?content="text/html;?charset=utf-8"?/>??

<title>view?order</title>??

</head>??

<body>??

????<h1>Order</h1>??

????<c:choose>??

????????<c:when?test="${empty?cart.items}">??

????????????<p>Your?cart?is?empty.</p>??

????????</c:when>??

????????<c:otherwise>??

????????????<table?border="1"?cellspacing="0">??

????????????????<tr>??

????????????????????<th>Item</th>??

????????????????????<th>Quantity</th>??

????????????????????<th>Unit?Price</th>??

????????????????????<th>Total</th>??

????????????????</tr>??

??

????????????????<c:forEach?var="item"?items="${cart.items}">??

????????????????????<tr>??

????????????????????????<td>${item.product.description}</td>??

????????????????????????<td>${item.quantity}</td>??

????????????????????????<td>${item.product.price}</td>??

????????????????????????<td>${item.totalPrice}</td>??

????????????????????</tr>??

????????????????</c:forEach>??

??

????????????????<tr>??

????????????????????<td>TOTAL:</td>??

????????????????????<td></td>??

????????????????????<td></td>??

????????????????????<td>${cart.totalPrice}</td>??

????????????????</tr>??

????????????</table>??

????????</c:otherwise>??

????</c:choose>??

??????

????<a?href="${flowExecutionUrl}&_eventId=confirm">Confirm</a>??

</body>??

</html>??

訪問地址：

http://localhost:8080/CartApp5/spring/index

?

顯示效果：

再擴(kuò)展一下：

如果我們將shopping.xml中的配置文件修改一下，改為flowScope時(shí)，我們?cè)趘iewOrder頁面也可以獲取products數(shù)據(jù)。

[html] view plaincopyprint?

<view-state?id="viewCart"?view="viewCart">??

????????<!--?在進(jìn)入?view?的?render?流程之后，在?view?真正?render出來之前?-->??

????????<on-render>??

????????????<!--?要在?viewCart?頁面中顯示商品，只需在?view-state?元素的?on-render?切入點(diǎn)調(diào)用?productService???

????????????????的?getProducts?方法，并將所得結(jié)果保存到?viewScope?中即可?-->??

????????????<evaluate?expression="productService.getProducts()"?result="flowScope.products"?/>??

????????</on-render>??

????????<transition?on="submit"?to="viewOrder"?/>??

????????<transition?on="addToCart"?to="addProductToCart"?/>??

????</view-state>??

viewOrder.jsp :

[html] view plaincopyprint?

<h2>Products?for?Your?Choice</h2>??

??

????<table>??

????<c:forEach?var="product"?items="${products}">??

????????<tr>??

????????????<td>${product.description}</td>??

????????????<td>${product.price}</td>??

????????</tr>???????????

????</c:forEach>??

????</table>??

????<a?href="${flowExecutionUrl}&_eventId=confirm">Confirm</a>??

效果圖：

總結(jié)：

? ? Spring Web Flow 應(yīng)用流程的方式解決了數(shù)據(jù)存取范圍的問題，并在解決數(shù)據(jù)存取范圍問題的同時(shí)，通過使用xml的方式來控制頁面間的流轉(zhuǎn)順序以及頁面間數(shù)據(jù)的傳輸，使得我們頁面間的跳轉(zhuǎn)變得更加靈活可控。

附源碼

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