java - JSF 属性初始化

Question

这个问题已经有答案了:

Accessing injected dependency in managed bean constructor causes NullPointerException (1 个回答)

已关闭 8 年前。

我遇到了以下问题:我有以下 JSF bean:

public class MailingBean {
    private RecipientService<?> recipientService;
    private SearchRecipientController searchRecipientController = new SearchRecipientController(recipientService);

    //Stuff, GET, SET
}

该 bean 已在 faces-config.xml 中初始化如下:

<managed-bean>
    <managed-bean-name>mailingBean</managed-bean-name>
    <managed-bean-class>path.to.package.MailingBean</managed-bean-class>
    <managed-bean-scope>session</managed-bean-scope>
    <managed-property>
        <property-name>recipientService</property-name>
        <value>#{playerService}</value>
    </managed-property>
</managed-bean>

最重要的是 new SearchRecipientController(recipientService)正在调用，recipientService一片空白。是否可以以某种方式指定初始化顺序？或者我该如何解决这个问题？

Answer 1

您不能在构造函数中使用托管属性(或如您在声明中的情况)。您应该使用 postconstruct 方法来完成您想要做的事情。管理属性在对象构造后设置。

private SearchRecipientController searchRecipientController;

@PostConstruct
public void init(){
     searchRecipientController = new SearchRecipientController(getRecipientService());
}

另一种方法是仅通过 getter 使用 searchRecipientController。

public SearchRecipientController getSearchRecipientController(){
    if(searchRecipientController==null){
        searchRecipientController = new SearchRecipientController(getRecipientService());
    }
    return searchRecipientController;
}