Bean 參考

如果評估環境已使用 Bean 解析器進行組態，您可以透過使用 @ 符號作為前綴，從表達式中查找 Bean。以下範例示範如何執行此操作

  • Java

  • Kotlin

ExpressionParser parser = new SpelExpressionParser();
StandardEvaluationContext context = new StandardEvaluationContext();
context.setBeanResolver(new MyBeanResolver());

// This will end up calling resolve(context, "someBean") on MyBeanResolver
// during evaluation.
Object bean = parser.parseExpression("@someBean").getValue(context);
val parser = SpelExpressionParser()
val context = StandardEvaluationContext()
context.setBeanResolver(MyBeanResolver())

// This will end up calling resolve(context, "someBean") on MyBeanResolver
// during evaluation.
val bean = parser.parseExpression("@someBean").getValue(context)

如果 Bean 名稱包含點 (.) 或其他特殊字元，您必須以字串文字的形式提供 Bean 的名稱 – 例如，@'order.service'。

若要存取 Factory Bean 本身，您應該改為在 Bean 名稱前面加上 & 符號。以下範例示範如何執行此操作

  • Java

  • Kotlin

ExpressionParser parser = new SpelExpressionParser();
StandardEvaluationContext context = new StandardEvaluationContext();
context.setBeanResolver(new MyBeanResolver());

// This will end up calling resolve(context, "&someFactoryBean") on
// MyBeanResolver during evaluation.
Object factoryBean = parser.parseExpression("&someFactoryBean").getValue(context);
val parser = SpelExpressionParser()
val context = StandardEvaluationContext()
context.setBeanResolver(MyBeanResolver())

// This will end up calling resolve(context, "&someFactoryBean") on
// MyBeanResolver during evaluation.
val factoryBean = parser.parseExpression("&someFactoryBean").getValue(context)