Struts 1.x中批量封装对象

Biegral 2019/5/14 3:39:55 1878

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1 发布产品

图2 查看产品图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

本文转载:CSDN博客

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