`FunctionExpression`

我们导入了 FunctionExpression 类（SpEL 的 Expression 接口的实现）以使用 lambda 和 泛型。当有来自 Core Spring 集成的隐式 Strategy 变体时，为 DSL 组件提供 Function<T, R> 选项以及 expression 选项。以下示例演示了如何使用函数表达式：

We introduced the FunctionExpression class (an implementation of SpEL’s Expression interface) to let us use lambdas and generics. The Function<T, R> option is provided for the DSL components, along with an expression option, when there is the implicit Strategy variant from Core Spring Integration. The following example shows how to use a function expression:

.enrich(e -> e.requestChannel("enrichChannel")
            .requestPayload(Message::getPayload)
            .propertyFunction("date", m -> new Date()))

FunctionExpression 也支持运行时类型转换，如同在 SpelExpression 中所做。

The FunctionExpression also supports runtime type conversion, as is done in SpelExpression.