如何在 Struts html:select 标签中使用枚举

发布于 2024-10-01 00:57:07 字数 689 浏览 2 评论 0原文

我目前正在尝试从枚举创建 html:select 标记，以便可以在特定对象中设置它：

class someClass {
    SomeEnum someProperties = null;
    public getSomeProperties() { return someProperties; }
    public setSomeProperties(SomeEnum e) { someProperties = e; }

带有 Struts 标记的 JSP：

<html:select name="someForm" property="someInstance.someProperties" >
   <html:option value="${someEnum.STANDARD}"><bean:message key="i18nkeystd"/>
   <html:option value="${someEnum.PREVENTIVE} "><bean:message key="i18nkeyprev"/>
</html:select>

但我目前收到“无法调用 someClass.setProperties -参数类型不匹配”异常。

有没有办法在 Struts 选择标签中使用枚举。

原文

I am currently trying to create a html:select tag from an enum so it could be set in a specific object:

class someClass {
    SomeEnum someProperties = null;
    public getSomeProperties() { return someProperties; }
    public setSomeProperties(SomeEnum e) { someProperties = e; }

The JSP with Struts tags:

<html:select name="someForm" property="someInstance.someProperties" >
   <html:option value="${someEnum.STANDARD}"><bean:message key="i18nkeystd"/>
   <html:option value="${someEnum.PREVENTIVE} "><bean:message key="i18nkeyprev"/>
</html:select>

But I am currently getting a "Cannot invoke someClass.setProperties - argument type mismatch" exception.

Is there a way to use an enum in a Struts select tag.

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同尘 2024-10-08 00:57:07

Struts 1 框架无法正确使用 Java 5 的功能，因为它也被设计为与 JDK 1.4 一起使用。

最新的稳定版本是 Struts 1.3.10。 Struts 1.3.10 的先决条件包括 Java 开发工具包版本 1.4或稍后。如果它在 JDK 1.4 上运行，则意味着它不使用 Java 5 的功能，其中包括枚举。

如果您至少使用 JDK 1.5，则可以在自己的代码中使用枚举（这很好），Struts 也将在 JDK 1.5 上运行（因为 Sun 非常努力地使它们向后兼容），但框架本身并不了解新功能添加到语言中。因此，对于将请求参数映射到 ActionForm 属性等自动操作，它不会提供正确的结果。

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半岛未凉 2024-10-08 00:57:07

我知道这是一个老问题，但我遇到了完全相同的问题，并且认为我会发布我使用的解决方法。

基本上，我将属性声明为字符串并利用 Enum.valueOf() 进行翻译。

这是我的 ActionForm 类：

package example;

import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServletRequest;

import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionMessage;

public class SearchByForm extends ActionForm{

    private static final long serialVersionUID = 5609098522501926807L;

    private String selectedOption;

    public enum SearchByOptions{
        NONE("-- Select One --"),
        OPTION1("Option 1"),
        OPTION2("Option 2"),
        OPTION3("Option 3"),
        OPTION4("Option 4"),
        OPTION5("Option 5");

        private String displayText;

        private SearchByOptions(String displayText){
            this.displayText = displayText;
        }

        public String getDisplayText(){
            return this.displayText;
        }
    }

    /**
     * @param selectedOption the selectedOption to set
     */
    public void setSelectedOption(String selectedOption) {
        this.selectedOption = selectedOption;
    }

    /**
     * @return the selectedOption
     */
    public String getSelectedOption() {
        return selectedOption;
    }

    public void reset(ActionMapping mapping, ServletRequest request)
    {
        setSelectedOption(SearchByOptions.NONE.toString());
    }

    @Override
    public ActionErrors validate(ActionMapping mapping, HttpServletRequest request) {

        ActionErrors errors = new ActionErrors();

        if( SearchByOptions.valueOf(getSelectedOption()) == SearchByOptions.NONE)
        {
           errors.add("selectedOption", new ActionMessage("error.common.html.select.required"));
        }

        return errors;
    }
}

这是 JSP：

<html>
    <body>
        <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
        <%@ taglib uri="http://jakarta.apache.org/struts/tags-html" prefix="html"%>

        <%
            pageContext.setAttribute("searchByOptions", example.SearchByForm.SearchByOptions.values());
        %>

        <div class="searchByInput"> 
            <html:form action="submitSearchBy">
                <html:select property="selectedOption">
                    <c:forEach var="searchByOption" items="${searchByOptions}">
                        <jsp:useBean id="searchByOption" type="example.SearchByForm.SearchByOptions"/>
                        <html:option value="${searchByOption}"><%= searchByOption.getDisplayText()%></html:option>
                    </c:forEach>
                </html:select> 
                <html:submit/>
            </html:form>
        </div>
    </body>
</html>

最后是 Action：

package example;

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 SubmitSearchByAction extends Action{

    public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request,HttpServletResponse response) throws Exception {
        ActionForward forwardAction;

        SearchByForm searchForm = (SearchByForm )form;

        switch(SearchByOptions.valueOf(searchForm.getSelectedOption())){
            case OPTION1:
                forwardAction = mapping.findForward(SearchByOptions.OPTION1.toString());
                break;
            case OPTION2:
                forwardAction = mapping.findForward(SearchByOptions.OPTION2.toString());
                break;
            case OPTION3:
                forwardAction = mapping.findForward(SearchByOptions.OPTION3.toString());
                break;
            case OPTION4:
                forwardAction = mapping.findForward(SearchByOptions.OPTION4.toString());
                break;
            case OPTION5:
                forwardAction = mapping.findForward(SearchByOptions.OPTION5.toString());
                break;
        }
        return forwardAction;
    }
}

I know this is an old question but I had the exact same problem and thought I would post the workaround that I used.

Basically, I declare the property as a String and utilize the Enum.valueOf() to translate.

Here is my ActionForm class:

package example;

import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServletRequest;

import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionMessage;

public class SearchByForm extends ActionForm{

    private static final long serialVersionUID = 5609098522501926807L;

    private String selectedOption;

    public enum SearchByOptions{
        NONE("-- Select One --"),
        OPTION1("Option 1"),
        OPTION2("Option 2"),
        OPTION3("Option 3"),
        OPTION4("Option 4"),
        OPTION5("Option 5");

        private String displayText;

        private SearchByOptions(String displayText){
            this.displayText = displayText;
        }

        public String getDisplayText(){
            return this.displayText;
        }
    }

    /**
     * @param selectedOption the selectedOption to set
     */
    public void setSelectedOption(String selectedOption) {
        this.selectedOption = selectedOption;
    }

    /**
     * @return the selectedOption
     */
    public String getSelectedOption() {
        return selectedOption;
    }

    public void reset(ActionMapping mapping, ServletRequest request)
    {
        setSelectedOption(SearchByOptions.NONE.toString());
    }

    @Override
    public ActionErrors validate(ActionMapping mapping, HttpServletRequest request) {

        ActionErrors errors = new ActionErrors();

        if( SearchByOptions.valueOf(getSelectedOption()) == SearchByOptions.NONE)
        {
           errors.add("selectedOption", new ActionMessage("error.common.html.select.required"));
        }

        return errors;
    }
}

And here is the JSP:

<html>
    <body>
        <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
        <%@ taglib uri="http://jakarta.apache.org/struts/tags-html" prefix="html"%>

        <%
            pageContext.setAttribute("searchByOptions", example.SearchByForm.SearchByOptions.values());
        %>

        <div class="searchByInput"> 
            <html:form action="submitSearchBy">
                <html:select property="selectedOption">
                    <c:forEach var="searchByOption" items="${searchByOptions}">
                        <jsp:useBean id="searchByOption" type="example.SearchByForm.SearchByOptions"/>
                        <html:option value="${searchByOption}"><%= searchByOption.getDisplayText()%></html:option>
                    </c:forEach>
                </html:select> 
                <html:submit/>
            </html:form>
        </div>
    </body>
</html>

And finally the Action:

package example;

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 SubmitSearchByAction extends Action{

    public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request,HttpServletResponse response) throws Exception {
        ActionForward forwardAction;

        SearchByForm searchForm = (SearchByForm )form;

        switch(SearchByOptions.valueOf(searchForm.getSelectedOption())){
            case OPTION1:
                forwardAction = mapping.findForward(SearchByOptions.OPTION1.toString());
                break;
            case OPTION2:
                forwardAction = mapping.findForward(SearchByOptions.OPTION2.toString());
                break;
            case OPTION3:
                forwardAction = mapping.findForward(SearchByOptions.OPTION3.toString());
                break;
            case OPTION4:
                forwardAction = mapping.findForward(SearchByOptions.OPTION4.toString());
                break;
            case OPTION5:
                forwardAction = mapping.findForward(SearchByOptions.OPTION5.toString());
                break;
        }
        return forwardAction;
    }
}

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