在JSF中的托管组件之间传递数据

问题描述

实际上可以在JSF中的托管组件之间传递任何数据吗?如果是，该如何实现?

Is it actually possible to pass any data between managed components in JSF? If yes, how to achieve this?

任何人都可以提供样品吗?

Could anyone provide any sample?

推荐答案

有几种方法.如果托管bean相互关联，则最干净的方法将是托管属性注入.假设Bean1具有与Bean2相同的范围或更大的范围.首先给Bean2一个Bean1属性:

There are several ways. If the managed beans are related to each other, cleanest way would be managed property injection. Let assume that Bean1 has the same scope or a broader scope than Bean2. First give Bean2 a Bean1 property:

public class Bean2 {
    private Bean1 bean1; // +getter +setter.
}

然后将faces-config.xml中的Bean1声明为Bean2的托管属性:

Then declare Bean1 in faces-config.xml to be a managed property of Bean2:

<managed-bean>
    <managed-bean-name>bean1</managed-bean-name>
    <managed-bean-class>com.example.Bean1</managed-bean-class>
    <managed-bean-scope>session</managed-bean-scope>
</managed-bean>

<managed-bean>
    <managed-bean-name>bean2</managed-bean-name>
    <managed-bean-class>com.example.Bean2</managed-bean-class>
    <managed-bean-scope>request</managed-bean-scope>
    <managed-property>
        <property-name>bean1</property-name>
        <value>#{bean1}</value>
    </managed-property>
</managed-bean>

通过这种方式，bean2实例可以立即访问bean1实例.

This way the bean2 instance has instant access to the bean1 instance.

如果由于某些原因不想使用托管属性注入，那么还可以获取 Application#evaluateExpressionGet() 进行编程访问.这是在Bean2中检索Bean1的示例:

If you don't want to use managed property injection for some reasons, then you can also grab Application#evaluateExpressionGet() to access it programmatically. Here's an example of retrieving Bean1 inside Bean2:

FacesContext context = FacesContext.getCurrentInstance();
Bean1 bean1 = (Bean1) context.getApplication().evaluateExpressionGet(context, "#{bean1}", Bean1.class);

但是，必须已在faces-config.xml中将Bean1声明为托管Bean bean1.

The Bean1 must however already be declared as managed bean bean1 in faces-config.xml.

有关在JSF内部传递数据的更多信息和提示，您可能会发现这篇文章有用.

For more info and hints about passing data around inside JSF, you may find this article useful.

这篇关于在JSF中的托管组件之间传递数据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！