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我正在使用继承的 JSF 应用程序。对它还是很陌生。

这是我正在使用的页面的屏幕截图：http: //goo.gl/GidpCD。这是一些考试软件，您正在查看的是问题管理。在此屏幕上，用户可以编写问题、引用问题来源、编写答案、关联到类别和关联图像。

当我向底部添加/删除答案时，我遇到了困难。

我怀疑我的问题出在 ViewState 上。

当我单击添加或删除答案时。页面重新加载，我丢失了 JSF dataTable 组件中的文件关联。ViewState 维护在页面上的所有其他表单元素中，只是该 dataTable 中的那些文件，我似乎无法理解。这是 JSF dataTable 组件（我将在下面完整列出代码）：

<h:dataTable id="table0" value="#{adminQuestions.filesList}" var="file" columnClasses="id,title,selected last" rendered="true" >
    <h:column>
        <f:facet name="header">File</f:facet>
        <h:graphicImage value="#{file.path2}" alt="" />
    </h:column>

    <h:column>
        <f:facet name="header">Title</f:facet>
        <h:outputText value="#{file.title}" />
    </h:column>
    <h:column>
        <f:facet name="header">Select files</f:facet>
        <h:selectBooleanCheckbox value="#{file.selected}" />
    </h:column>
</h:dataTable>

这是触发添加添加答案方法的 JSF 按钮组件：

<h:commandButton value="#{msgs.addButton}" action="#{adminQuestions.addQuestionToAnswerRow}" />

这是那个add answer方法：

public String addQuestionToAnswerRow() {
    if(this.questionToAnswerList.size() < 8) {
        // set the scroll
        if(FacesContext.getCurrentInstance().getMessageList().size() > 0) {
            this.scroll = false;
        }
        else {
            this.scroll = true;
        }
        //Create a new answer, set the current question, and add it to the collection
        Answers answer_local = new Answers();
        QuestionToAnswer qta_local = new QuestionToAnswer();
        answer_local.setTitle(this.inputTextAnswer);
        answer_local.setDescription(this.inputTextAnswer);
        answer_local.setCorrect(this.correctAnswer);
        qta_local.setAnswers(answer_local);
        qta_local.setAnswer(this.questionToAnswerList.size() + 1);
        qta_local.setQuestions(this.question);
        this.questionToAnswerList.add(qta_local);
        // reset the input fields
        this.inputTextAnswer = "";
        this.correctAnswer = false;

        List<File1> thisFilesList = getFilesList();

        QuestionsToFiles qtf;
        List<QuestionsToFiles> qtfc = new ArrayList<QuestionsToFiles>();
        if(this.filesList != null) {
            for(Iterator<File1> entries = this.filesList.iterator(); entries.hasNext();) {
                File1 file_temp = entries.next();
                if(file_temp.isSelected()) {
                    qtf = new QuestionsToFiles();
                    qtf.setQuestions(this.question);
                    qtf.setFile1(file_temp);
                    qtfc.add(qtf);
                }
            }
        }

        return null;
    }
    else {
        JSFUtils.addErrorMessage("No more than eight answers are allowed: ", "The question cannot have more than eight answers");
        return null;
    }
}

这是触发删除方法的 JSF 按钮组件

<h:commandButton value="#{msgs.deleteButton}" action="#{adminQuestions.deleteQuestionToAnswerRow(a)}" />

和删除方法：

public String deleteQuestionToAnswerRow(QuestionToAnswer qta_local) {
    // set the scroll
    if(FacesContext.getCurrentInstance().getMessageList().size() > 0) {
        this.scroll = false;
    }
    else {
        this.scroll = true;
    }
    //Iterate through the category exam collection and delete the associated category so it's reflected on the page
    for (Iterator<QuestionToAnswer> itr = this.questionToAnswerList.iterator(); itr.hasNext();) {
        QuestionToAnswer qta_temp = itr.next();
        if(qta_temp == qta_local) {
            qta_temp.setQuestions(null);
            qta_temp.setAnswers(null);
            itr.remove();
            return null;
        }
    }
    return null;
}

谢谢参观。

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