如何在JSF中的表中动态添加一行? [英] How to Dynamically add a row in a table in JSF?

问题描述

在我的应用程序中，我需要通过单击按钮添加一行，并且该按钮将在所有行中.需要帮助来做到这一点?

In my application i need to add a row on a click of a button and this button will be in all the rows. Need help to do this?

项目类别

public class Item {
 public Item()
{

}
private String value;
public Item(String value) { this.value = value; }
public void setValue(String value) { this.value = value; }
public String getValue() { return value; }
}

管理 Bean 类

public class MyMB 
{
private List<Item> list;    

public void addItem() { // JSF action method
    list.add(new Item("Default"));
    Iterator<Item> iterator = list.iterator();
    while(iterator.hasNext())
    {
        Item item = (Item)iterator.next();
        System.out.println(item.getValue());
    }
    System.out.println();
    }
/**
 * @return the list
 */
public List<Item> getList() {
    if(list==null)
    {
        loadList();
    }
    return list;
}
private void loadList() {
    list = new ArrayList<Item>();
    list.add(new Item("Data"));
}

}

JSF 代码

<h:form>
   <rich:dataTable value="#{myMB.list}" var="item" id="tabel">
    <h:column><h:inputText value="#{item.value}" /></h:column>
    <h:column><a4j:commandButton value="Add"  actionListener="#{myMB.addItem}" reRender="tabel"/></h:column>

推荐答案

您需要做的基本上实际上只是在 h 的 value 属性后面的数据模型中添加一个空对象:数据表.

All you need to do is basically indeed just adding an empty object to the datamodel behind the value attribute of h:dataTable.

但同样的空行也需要在后续请求中保留.如果支持 bean 是请求范围的，则数据模型将重新加载而没有空行.当 bean 处于会话范围内时，这一切都应该有效.

But the same empty row needs to be preserved in the subsequent request as well. If the backing bean is request scoped, then the datamodel get reloaded without the empty row. This all should work when the bean is session scoped.

此外，您的 JSF 代码中有几个错误.h:dataTable var 属性缺失，列内容需要在 h:column 内.

Further there are several errors in your JSF code. The h:dataTable var attribute is missing and the column content needs to be inside a h:column.

<h:form>
    <h:dataTable value="#{bean.list}" var="item">
        <h:column><h:inputText value="#{item.value}" /></h:column>
    </h:dataTable>
    <h:commandButton value="Add" action="#{bean.add}"/>
</h:form>

会话或视图范围 bean 可以如下所示:

A session or view scoped bean can look like this:

public class Bean {
    private List<Item> list;

    public Bean() {
        list = new ArrayList<Item>();
    }

    public void add() {
        list.add(new Item());
    }

    public List<Item> getList() {
        return list;
    }
}

Item 类当然应该有一个默认的无参数构造函数.通常这已经是隐式可用的，但是如果你用参数定义自己的构造函数，那么它就不再可用了.您需要明确定义它，否则您不能再执行 Item item = new Item(); 了.

The Item class should of course have a default no-arg constructor. Normally this is already implicitly available, but if you define your own constructor with arguments, then it is not available anymore. You'll need to explicitly define it, otherwise you cannot do Item item = new Item(); anymore.

public class Item {

    private String value;

    public Item() {
        // Keep default constructor alive.
    }

    public Item(String value) {
        this.value = value;
    }

    // ...
}

如果您希望将 bean 保留在请求范围，那么您需要维护新添加项的数量，以便 bean 在加载时可以保持相同的数量.>

If you prefer to keep the bean in the request scope, then you'll need to maintain the amount of newly added items, so that the bean can preserve the same amount on load.

public class Bean {
    private List<Item> list;
    private HtmlInputHidden count = new HtmlInputHidden();

    public Bean() {
        count.setValue(0);
    }

    public void add() {
        list.add(new Item());
    }

    public List<Item> getList() {
        if (list == null) loadList();
        return list;
    }

    public HtmlInputHidden getCount() {
        return count;
    }

    public void setCount(HtmlInputHidden count) {
        this.count = count;
    }

    private void loadList() {
        list = new ArrayList<Item>();

        // Preserve list with newly added items.
        for (int i = 0; i < (Integer) count.getValue(); i++) {
            list.add(new Item());
        }
    }
}

您只需将以下内容添加到 JSF 页面的 :

You'll only need to add the following to the <h:form> of the JSF page:

<h:inputHidden binding="#{bean.count}" converter="javax.faces.Integer" />

有关以任何方式使用数据表的更多见解，您可能会发现这篇文章很有用:使用数据表.它还包含一个 WAR 文件，其中包含请求和会话范围内的大量示例.

For more insights about using datatables in any way you may find this article useful: Using Datatables. It also contains a WAR file with lot of examples in both request and session scope.

这篇关于如何在JSF中的表中动态添加一行?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！