在JSF中的托管组件之间传递数据 [英] Passing data between managed components in JSF

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

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.

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