如何在复合组件的Backing Component中访问EntityManager？

Question

我制作了一个带有支持组件的复合组件：

复合组件的Xhtml：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://xmlns.jcp.org/jsf/html"
      xmlns:p="http://primefaces.org/ui"
      xmlns:composite="http://java.sun.com/jsf/composite" xmlns:c="http://java.sun.com/jsp/jstl/core">

    <composite:interface componentType="editorCompositeComponent">
        <!-- ...bunch of attributes... -->
        <composite:attribute name="content" type="java.lang.String" default="" />
    </composite:interface>

    <composite:implementation>
        <!-- ... other components ... -->
        <p:editor widgetVar="editorWidget" value="#{cc.attrs.content}" width="600" maxlength="8000" />
        <p:commandButton action="#{cc.save(cc.attrs.caseId)}" value="Save" />
    </composite:implementation>

</html>

支持组件：

@FacesComponent("editorCompositeComponent")
public class EditorCompositeComponent extends UINamingContainer {

    private String content;
    // bunch of other variables

    public void save(String caseId) {

    MemoFile memoFile = new MemoFile();
    memoFile.setContent(content);
    memoFileService = new MemoFileService();
    // Normally this service would be Injected but Injection
    // isn't possible in @FacesComponent

    memoFileService.save(memoFile);
    // the save-method just calls EntityManager's merge etc.
    // It works well in all the ManagedBeans
    }
    // all the getters and setters
}

所以，不能注入东西，因此不能找到 EntityManager，那么如何在复合组件中持久化编辑器的内容呢？

Answer 1

UI 组件不支持依赖注入。职责的紧密耦合有点过分了。 UI 组件实例不应由容器管理。

最好的办法是为任务创建一个单独的请求范围托管 bean。

@Named
@RequestScoped
public class EditorCompositeBean {
    // ...
}

您可以将复合组件实例传递给它的操作方法：

<p:commandButton ... action="#{editorCompositeBean.save(cc)}" />

或者改用那个 bean 作为模型：

<composite:interface componentType="editorCompositeComponent">
    <composite:attribute name="value" type="com.example.EditorCompositeBean" />
</composite:interface>

<composite:implementation>
    <p:editor ... value="#{cc.attrs.value.content}" />
    <p:commandButton ... action="#{cc.attrs.value.save}" />
</composite:implementation>

如何在复合组件的Backing Component中访问EntityManager？

How to access EntityManager in the Backing Component of a composite component?

jsf

primefaces

composite-component