Struts 1.x中批量封装对象

应用场景

批量发布产品信息。页面输出如下图所示：

图1 发布产品

图2 查看产品

具体实现

首先创建代表产品的类 Product.java，代码如下：

package tipsAndTricks; import java.sql.Date; public class Product { private String name; private double price; private Date dateOfProduction; public Date getDateOfProduction() { return dateOfProduction; } public void setDateOfProduction(Date dateOfProduction) { this .dateOfProduction = dateOfProduction; } public String getName() { return name; } public void setName(String name) { this .name = name; } public double getPrice() { return price; } public void setPrice( double price) { this .price = price; } }

本例子中的dateOfProduction属性使用了java.sql.Date，而不是java.util.Date。这是因为Struts 1.x不支持请求参数到java.util.Date的转换，归根到底是由于org.apache.commons.beanutils.ConvertUtilsBean.convert()不支持关于java.util.Date的转换。另外，值得注意的是common-beanutils是通过java.sql.Date.valueOf（）方法工作的，所以在页面输入的字符串的格式必须为“yyyy-MM-dd”。

实现上述功能大概有三种方法，下面我会分别对两种方法进行详细的讲述。

方法一、动态表单（Dynamic Actoin Form）+ 数组

首先，让我们来看一下Struts的配置文件WEB-INF/struts-config.xml，内容如下：

<? xml version="1.0" encoding="UTF-8" ?> <! DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.2//EN" "http://struts.apache.org/dtds/struts-config_1_2.dtd" > < struts-config > < data-sources /> < form-beans > < form-bean name ="dynaProductsForm" type ="org.apache.struts.action.DynaActionForm" > < form-property name ="products" type ="tipsAndTricks.Product[]" size ="3" /> </ form-bean > </ form-beans > < global-exceptions /> < global-forwards /> < action-mappings > < action attribute ="dynaProductsForm" input ="/addProducts.jsp" name ="dynaProductsForm" path ="/batchWrappingWithArray" scope ="request" type ="tipsAndTricks.BatchWrappingWithArrayAction" validate ="false" > < forward name ="success" path ="/viewProducts.jsp" /> </ action > </ action-mappings > < message-resources parameter ="tipsAndTricks.ApplicationResources" /> </ struts-config >

我想这些配置应该用不着怎么解释了，有Struts 1.x验证的朋友对此都不会陌生。因此，接下来创建/addProducts.jsp文件，代码如下：

<% @ page language = " java " pageEncoding = " utf-8 " %> <% @ taglib uri = " http://struts.apache.org/tags-html " prefix = " html " %> <% @ taglib uri = " http://java.sun.com/jsp/jstl/core " prefix = " c " %> <! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" > < html > < head > < title > Add Products </ title > </ head > < body > < html:form action ="/batchWrappingWithArray" method ="post" > < table border ="0" > < tr style ="background-color:powderblue; font-weight:bold;" > < td > Product Name </ td > < td > Price </ td > < td > Date of production </ td > </ tr > < c:forEach var ="products" items ="${dynaProductsForm.map.products}" > < tr > < td >< html:text indexed ="true" name ="products" property ="name" /></ td > < td >< html:text indexed ="true" name ="products" property ="price" /></ td > < td >< html:text indexed ="true" name ="products" property ="dateOfProduction" /></ td > </ tr > </ c:forEach > < tr > < td colspan ="3" >< html:submit /></ td > </ tr > </ table > </ html:form > </ body > </ html >

例中，我使用了JSTL 1.1，如果大家还没有尝试过使用JSP 2.0的JSTL和EL，建议大家去看看相关文章。上面的<c:forEach />的作用是到dynaProductsForm的map属性中取出products数组，并对其进行遍历，再依靠<html:text />标志将products的元素的属性以输入框的形式输出。<html:text />标志的属性indexed="true"则表示在输出HTML时，将<input>的命名为类似products[0].name的名字。

然后，再创建/viewProducts.jsp页面，内容如下：

<% @ page language = " java " pageEncoding = " utf-8 " %> <% @ taglib uri = " http://java.sun.com/jsp/jstl/core " prefix = " c " %> <! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" > < html > < head > < title > View Products </ title > </ head > < body > < table border ="0" > < tr style ="background-color:powderblue; font-weight:bold;" > < td > Product Name </ td > < td > Price </ td > < td > Date of production </ td > </ tr > < c:forEach var ="product" items ="${products}" > < tr > < td > ${product.name} </ td > < td > ${product.price} </ td > < td > ${product.dateOfProduction} </ td > </ tr > </ c:forEach > </ table > </ body > </ html >

我想这份也不多作说明。不过大家可以通过上述代码看出使用JSTL + EL的确比Struts 1.x的logic + bean要方便和简洁。不仅如此，EL还支持一定的运算符和函数操作。

最后是建立Action文件 BatchWrappingWithArrayAction.java，代码如下：

package tipsAndTricks; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.struts.action.Action; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; import org.apache.struts.action.DynaActionForm; public class BatchWrappingWithArrayAction extends Action { public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) { DynaActionForm dynaProductsForm = (DynaActionForm) form; request.setAttribute( " products " , dynaProductsForm.get( " products " )); return mapping.findForward( " success " ); } }

此Action将动态表单传过来的products数组放到request中，转到/viewProducts.jsp。发布运行应用程序，在浏览器的地址栏中输入：http://localhost:8080/Struts1_Batch/addProducts.jsp。效果请参考如图1、图2。

在/addProducts.jsp的“Date of production”必须以（yyyy-MM-dd）的形式正确填写，且不能为空。

方法二、表单（Actoin Form）+ 列表（List）

方法一虽然简单，但是有一个明显的缺点——数组的长度已经固定，故我们不能在运行时通过程序设置对象数量。下面将要介绍的方法可以很好地解决这个问题。

首先，我们要创建类 AutoInitArrayList.java，代码如下：

package tipsAndTricks; import java.util.ArrayList; public class AutoInitArrayList < T > extends ArrayList < T > { private static final long serialVersionUID = 1L ; private Class < T > t = null ; public AutoInitArrayList(Class < T > t) { this .t = t; } @Override public T get( int index) { try { while (index >= size()) { add(t.newInstance()); } } catch (Exception e) { e.printStackTrace(); } return super .get(index); } }

AutoInitArrayList继承ArrayList并重载get()方法，作用就是在Struts 1.x框架调用这个方法时，如果index超出列表大小，则会实例化新项放到列表中，避免出现(IndexOutOfBoundsException)异常。

接着，让我们看Struts的配置，内容如下：

<? xml version="1.0" encoding="UTF-8" ?> <! DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.2//EN" "http://struts.apache.org/dtds/struts-config_1_2.dtd" > < struts-config > < data-sources /> < form-beans > < form-bean name ="dynaProductsForm" type ="org.apache.struts.action.DynaActionForm" > < form-property name ="products" type ="tipsAndTricks.Product[]" size ="3" /> </ form-bean > < form-bean name ="normalProductsForm" type ="tipsAndTricks.NormalProductsForm" /> </ form-beans > < global-exceptions /> < global-forwards /> < action-mappings > < action attribute ="dynaProductsForm" input ="/addProducts.jsp" name ="dynaProductsForm" path ="/batchWrappingWithArray" scope ="request" type ="tipsAndTricks.BatchWrappingWithArrayAction" validate ="false" > < forward name ="success" path ="/viewProducts.jsp" /> </ action > < action attribute ="normalProductsForm" input ="/addProducts.jsp" name ="normalProductsForm" path ="/batchWrappingNormal" scope ="request" type ="tipsAndTricks.BatchWrappingNormalAction" validate ="false" > < forward name ="success" path ="/viewProducts.jsp" /> </ action > </ action-mappings > < message-resources parameter ="tipsAndTricks.ApplicationResources" /> </ struts-config >

然后，创建表单类 NormalProductsForm.java，代码如下：

package tipsAndTricks; import java.util.List; import org.apache.struts.action.ActionForm; public class NormalProductsForm extends ActionForm { private List products = new AutoInitArrayList < Product > (Product. class ); public List getProducts() { return products; } public void setProducts(List products) { this .products = products; } }

接下来是Action类 BatchWrappingNormalAction.java，代码如下：

/**/ /* * Generated by MyEclipse Struts * Template path: templates/java/JavaClass.vtl */ package tipsAndTricks; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.struts.action.Action; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; public class BatchWrappingNormalAction extends Action { public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) { NormalProductsForm normalProductsForm = (NormalProductsForm) form; request.setAttribute( " products " , normalProductsForm.getProducts()); return mapping.findForward( " success " ); } }

基本上与方法一的Action一样。下面，再看看新的输入文件/addProducts2.jsp，内容如下：

<% @ page language = " java " pageEncoding = " utf-8 " %> <% @ taglib uri = " http://struts.apache.org/tags-html " prefix = " html " %> <% @ taglib uri = " http://java.sun.com/jsp/jstl/core " prefix = " c " %> <! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" > < html > < head > < title > Add Products </ title > </ head > < body > < html:form action ="/batchWrappingNormal" method ="post" > < table border ="0" > < tr style ="background-color:powderblue; font-weight:bold;" > < td > Product Name </ td > < td > Price </ td > < td > Date of production </ td > </ tr > < c:forEach begin ="0" end ="2" var ="i" > < tr > < td >< input name ="products[${i}].name" /></ td > < td >< input name ="products[${i}].price" /></ td > < td >< input name ="products[${i}].dateOfProduction" /></ td > </ tr > </ c:forEach > < tr > < td colspan ="3" >< html:submit /></ td > </ tr > </ table > </ html:form > </ body > </ html >

/addProducts2.jsp主要作用组装<input>的元素名称，Struts 1.x对名称格式类似“xxx[9].xx”的请求，会进行封装。发布运行应用程序，在浏览器的地址栏中输入：http://localhost:8080/Struts1_Batch/addProducts2.jsp。效果请参考如图1、图2。

总结

两种方法各有优缺点，选择原则是如果不需要动态设置元素个数，则使用方法一，否则请使用方法二。

文章来源：http://www.blogjava.net/max/archive/2006/12/08/86439.html