Question

在struts2中我有一些s：选择列表字段

<s:select name="oneObj" id="ddlOne" list="oneList" 
<s:select name="twoObj" id="ddlTwo" list="{'0A','0B','1C','1Z'}"
<s:select name="thrObj" id="ddlThr" list=???"

首先，在服务器上调用 actionClass.getOneList（） 来填充列表，第二个列表是硬编码的。

我真正想要的是第三个为页面的JSP生成列表 IN 。该列表将包含200个字符串，可以使用Java或javascript在 for 循环中轻松构建为数组。我不想用Java生成列表，并且有一个属性，getter，setter使我的动作类混乱，因为列表不是动态的，也不是由服务器上的数据定义的（如一个）并且我不希望使用{}获取200个项目的静态列表（例如两个）。< / p>

有没有办法做到这一点？可以将javascript变量用作此列表吗？可以在JSP中使用java代码来创建此列表吗？

另外，我真正可以使用的是 list 的完整描述/语法。官方struts2文档说

list : `Iterable` source to populate from. If the list is a Map (key, value), the Map key will become the option 'value' parameter and the Map value will become the option body.

没有显示 list 的任何语法。是否有其他文档描述了struts标记/属性，并使用 ＆＃34;，$，＃，{ 来定义此列表？

Answer 1

有很多方法可以做到这一点：

在您的Action中或在其他人扩展的BaseAction中使用包含静态类型列表的静态列表，然后将其注入页面（通过getter）。
使用静态方法
使用动态方法
既然你问过，你在定义Struts标签时显然不能使用Javascript，但是你可以在页面加载时启动javascript来改变生成的HTML选择对象。但这很昂贵，没有缓存，也没有同步，如果它中断，你的选择就不会被填充......这绝对是最糟糕的选择。

由于列表是静态的，并且它永远不会更改，因此最好的选择是生成一次，然后将STATICALLY包含在代码中。好吧，迭代数字达到200并不是什么大问题，我们谈论的是纳秒，但如果你有数百万用户，那么它可能就不那么重要了。每次都这样做是非常愚蠢的，以防止在Java文件中有一个大的静态声明...把它放在一个独立的文件中，并静态使用它以避免混乱行为（这不是一个很好的理由混乱你的JSP，顺便说一下。

注意：您也可以使用带有min-max和s：set的迭代器生成此List，但是您遇到与上面相同的问题，对每个用户来说都是无用且（可能）成本高昂的操作。 / p>

修改：

我猜你的意思是静态＆＃39;就像在Java＆＃39;静态＆＃39;变量。是的我同意一个不变的列表比静态更好，但我不想在我的服务器代码中使用这个列表。在我提到的另一个半相关问题中（可能是由于结构不佳 - 我继承了这个应用程序）这个列表在一个JSP中使用，但是3个动作类/对象需要它。因此，如果列表是Java，我需要在所有这些类中使用变量/ setter / getter。这就是为什么我想在JSP中使用javascript或Java以某种方式完成它。而且我也不愿意为此定义一个超类。 - user3708842 12小时前

什么是动态＆＃39;方法？如何在加载时使用javascript来更改列表？那会是读取struts生成的HTML并修改它吗？我可能不会使用它，但是怎么做到的？最后将它放在一个独立的文件中，并静态使用它以避免混乱的操作＆＃39; - 如何避免动作类中的属性/ setter / getter？ - user3708842 12小时前

我猜你的整个事情过于复杂......只需使用静态列表，故事结束。你不需要吸气剂，制定者或其他任何东西。你生成一次，并永远使用它。 0 cpu-cost。在类和JSP中都有。免费：）

您甚至不需要编写一次，使用a code like this生成它：

StringBuffer sb = new StringBuffer(); sb.append("public final static List<String> myStaticList = java.util.Arrays.asList("); for (int x=0;x<100;x++){ sb.append("\""+x+"X\","); } for (int x=0;x<100;x++){ sb.append("\""+x+"Y\""); sb.append(x<99 ? "," : ");"); } System.out.println(sb);

最后为前十个X和Y数字添加前导零。

复制输出，并将这些静态内容放在某个扩展（或不扩展）的类中，在实现（或不实现）的接口中，在枚举或静态嵌套类中，无论在何处。例如。在一个界面（不应该像那样使用，但谁在乎）：

package foo.bar.package; interface iMyStaticStuff { public final static List<String> myStaticList = Arrays.asList("0X","1X","2X","3X","4X","5X","6X","7X","8X","9X","10X","11X","12X","13X","14X","15X","16X","17X","18X","19X","20X","21X","22X","23X","24X","25X","26X","27X","28X","29X","30X","31X","32X","33X","34X","35X","36X","37X","38X","39X","40X","41X","42X","43X","44X","45X","46X","47X","48X","49X","50X","51X","52X","53X","54X","55X","56X","57X","58X","59X","60X","61X","62X","63X","64X","65X","66X","67X","68X","69X","70X","71X","72X","73X","74X","75X","76X","77X","78X","79X","80X","81X","82X","83X","84X","85X","86X","87X","88X","89X","90X","91X","92X","93X","94X","95X","96X","97X","98X","99X","0Y","1Y","2Y","3Y","4Y","5Y","6Y","7Y","8Y","9Y","10Y","11Y","12Y","13Y","14Y","15Y","16Y","17Y","18Y","19Y","20Y","21Y","22Y","23Y","24Y","25Y","26Y","27Y","28Y","29Y","30Y","31Y","32Y","33Y","34Y","35Y","36Y","37Y","38Y","39Y","40Y","41Y","42Y","43Y","44Y","45Y","46Y","47Y","48Y","49Y","50Y","51Y","52Y","53Y","54Y","55Y","56Y","57Y","58Y","59Y","60Y","61Y","62Y","63Y","64Y","65Y","66Y","67Y","68Y","69Y","70Y","71Y","72Y","73Y","74Y","75Y","76Y","77Y","78Y","79Y","80Y","81Y","82Y","83Y","84Y","85Y","86Y","87Y","88Y","89Y","90Y","91Y","92Y","93Y","94Y","95Y","96Y","97Y","98Y","99Y"); }

然后在Java中使用它：

public class Foo extends ActionSupport implements iMyStaticStuff{ public String execute(){ System.out.println(myStaticList); return SUCCESS; } }

和JSP

<s:select list="%{@foo.bar.package.iMyStaticStuff@myStaticList}" ... />

我如何构建struts2：在JSP中选择列表

1 个答案: