如何扩展Spring注解@Transactional

发布于 2024-09-16 08:25:26 字数 798 浏览 5 评论 0原文

我必须在我的网络应用程序中使用 3 个不同的事务管理器。所以我根据编写了自己的注释Spring参考（第10.5.6.3节自定义快捷方式注释）。

一个注释（用于使用一个特定的事务管理器）如下所示：

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import org.springframework.transaction.annotation.Transactional;

@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Transactional("customer")
public @interface CustomerTX{


}

使用自定义的 @CustomerTX 注释对我的服务层进行注释时，一切正常。但我必须为我的注释提供更多选项，例如 readonly=true、rollbackFor= 等。由于您无法“扩展”注释（我实际上只需要从 Spring 扩展 @Transactional 注释），那么正确的实现是什么？

原文

I have to use 3 different transaction managers in my webapp. So I wrote my own Annotation according to the Spring reference (Section 10.5.6.3 Custom shortcut annotations).

One annotation (for using one specific transactionmanager) looks like this:

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import org.springframework.transaction.annotation.Transactional;

@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Transactional("customer")
public @interface CustomerTX{


}

Everything is working fine when annotating my service layer with the customized @CustomerTX annotation. But I have to provide more options for my annotation, like readonly=true, rollbackFor= and so on. As you cannot "extend" an annotation (I really just need to extend the @Transactional annotation from Spring), whats the correct implementation for this?

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韵柒 2024-09-23 08:25:26

在 Spring 4 中你可以做到这一点。如中所述文档

元注释也可以组合起来创建组合注释。例如，Spring MVC 中的 @RestController 注解由 @Controller 和 @ResponseBody 组成。

此外，组合注释可以选择重新声明元注释中的属性以允许用户自定义。当您只想公开元注释属性的子集时，这尤其有用。例如，Spring 的 @SessionScope 注释将范围名称硬编码为会话，但仍然允许自定义 proxyMode。

@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Scope(WebApplicationContext.SCOPE_SESSION)
public @interface SessionScope {

    /**
     * Alias for {@link Scope#proxyMode}.
     * <p>Defaults to {@link ScopedProxyMode#TARGET_CLASS}.
     */
    @AliasFor(annotation = Scope.class)
    ScopedProxyMode proxyMode() default ScopedProxyMode.TARGET_CLASS;

}

In spring 4 you can do that. As stated in the documentation

Meta-annotations can also be combined to create composed annotations. For example, the @RestController annotation from Spring MVC is composed of @Controller and @ResponseBody.

In addition, composed annotations may optionally redeclare attributes from meta-annotations to allow user customization. This can be particularly useful when you want to only expose a subset of the meta-annotation’s attributes. For example, Spring’s @SessionScope annotation hardcodes the scope name to session but still allows customization of the proxyMode.

@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Scope(WebApplicationContext.SCOPE_SESSION)
public @interface SessionScope {

    /**
     * Alias for {@link Scope#proxyMode}.
     * <p>Defaults to {@link ScopedProxyMode#TARGET_CLASS}.
     */
    @AliasFor(annotation = Scope.class)
    ScopedProxyMode proxyMode() default ScopedProxyMode.TARGET_CLASS;

}

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