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JSF MVC设计问题

发布于 2024-11-01 18:52:20 字数 118 浏览 0 评论 0原文

我有一个 JSF 支持 bean 设计问题。现在，我的支持 bean 保存 UI 显示信息和业务模式数据。人们建议模型和视图应该分开。那么创建不同的 bean 来保存 UI 显示数据并让支持 bean 引用它是个好主意吗？

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二智少女猫性小仙女 2024-11-08 18:52:20

那么创建不同的 bean 来保存 UI 显示数据并让支持引用它是个好主意吗？

是的，否则您将继续从模型映射数据以查看自己，同时您也可以让 JSF/ EL 这样做。顺便说一句，它不一定需要是 JSF @ManagedBean。

例如，这很差：

@ManagedBean
@RequestScoped
public class ProductEditor {

    private String productName;
    private String productDescription;
    private BigDecimal productPrice;

    public String add() {
        Product product = new Product();
        product.setName(productName);
        product.setDescription(productDescription);
        product.setPrice(productPrice);
        productService.save(product);
        return "view";
    }

    // In total 6 getters and setters.
}

使用

<h:form>
    <h:inputText value="#{productEditor.productName}" />
    <h:inputTextarea value="#{productEditor.productDescription}" />
    <h:inputText value="#{productEditor.productPrice}">
        <f:convertNumber type="currency" currencySymbol="$" />
    </h:inputText>
    <h:commandButton value="Add" action="#{productEditor.add}" />
</h:form>

这更好

@ManagedBean
@RequestScoped
public class ProductEditor {

    private Product product;

    @PostConstruct
    public void init() {
        product = new Product(); // You could also preload from DB based on some ID as request parameter.
    }

    public String add() {
        productService.save(product);
        return "view";
    }

    // Only 1 getter.
}

请参见

<h:form>
    <h:inputText value="#{productEditor.product.name}" />
    <h:inputTextarea value="#{productEditor.product.description}" />
    <h:inputText value="#{productEditor.product.price}">
        <f:convertNumber type="currency" currencySymbol="$" />
    </h:inputText>
    <h:commandButton value="Add" action="#{productEditor.add}" />
</h:form>

此 JSF 2.0 教程。

so is it good idea to create different bean the holding UI display data and have backing have reference to it?

Yes, otherwise you keep mapping the data from model to view yourself while you can also just let JSF/EL do that. It does by the way not necessarily need to be a JSF @ManagedBean.

E.g. this is poor:

@ManagedBean
@RequestScoped
public class ProductEditor {

    private String productName;
    private String productDescription;
    private BigDecimal productPrice;

    public String add() {
        Product product = new Product();
        product.setName(productName);
        product.setDescription(productDescription);
        product.setPrice(productPrice);
        productService.save(product);
        return "view";
    }

    // In total 6 getters and setters.
}

with

<h:form>
    <h:inputText value="#{productEditor.productName}" />
    <h:inputTextarea value="#{productEditor.productDescription}" />
    <h:inputText value="#{productEditor.productPrice}">
        <f:convertNumber type="currency" currencySymbol="$" />
    </h:inputText>
    <h:commandButton value="Add" action="#{productEditor.add}" />
</h:form>

This is better

@ManagedBean
@RequestScoped
public class ProductEditor {

    private Product product;

    @PostConstruct
    public void init() {
        product = new Product(); // You could also preload from DB based on some ID as request parameter.
    }

    public String add() {
        productService.save(product);
        return "view";
    }

    // Only 1 getter.
}

with

<h:form>
    <h:inputText value="#{productEditor.product.name}" />
    <h:inputTextarea value="#{productEditor.product.description}" />
    <h:inputText value="#{productEditor.product.price}">
        <f:convertNumber type="currency" currencySymbol="$" />
    </h:inputText>
    <h:commandButton value="Add" action="#{productEditor.add}" />
</h:form>

See also the examples as presented by this JSF 2.0 tutorial.

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