如何在 Grails 3 中使用过滤器而不是拦截器？答案

【问题标题】：How to use filters in Grails 3 instead of interceptors?如何在 Grails 3 中使用过滤器而不是拦截器？
【发布时间】：2017-04-25 05:58:59
【问题描述】：

Interceptors vs Filters 下的 Grails 3 文档说：

In versions of Grails prior to Grails 3.0, Grails supported the notion of filters. These are still supported for backwards compatibility but are considered deprecated.

我有一个大型 Grails 2.5 应用程序正在迁移到 Grails 3.2，并且希望继续使用过滤器。

如何使过滤器在 Grails 3.* 中工作？

根据 [http://docs.grails.org/latest/guide/upgrading.html]，我添加了compile 'org.grails:grails-plugin-filters:3.0.12' 并将过滤器类从grails-app/conf 移动到grails-app/controllers，但随后出现以下异常：

java.lang.NullPointerException: null
    at java.beans.Introspector.getPublicDeclaredMethods(Introspector.java:1337)
    at java.beans.Introspector.getTargetMethodInfo(Introspector.java:1197)
    at java.beans.Introspector.getBeanInfo(Introspector.java:426)
    at java.beans.Introspector.getBeanInfo(Introspector.java:173)
    at groovy.lang.MetaClassImpl$15.run(MetaClassImpl.java:3318)
    at java.security.AccessController.doPrivileged(Native Method)
    at groovy.lang.MetaClassImpl.addProperties(MetaClassImpl.java:3316)
    at groovy.lang.MetaClassImpl.initialize(MetaClassImpl.java:3293)
    at org.codehaus.groovy.reflection.ClassInfo.getMetaClassUnderLock(ClassInfo.java:260)
    at org.codehaus.groovy.reflection.ClassInfo.getMetaClass(ClassInfo.java:302)
    at org.grails.plugins.web.filters.FilterToHandlerAdapter.$getStaticMetaClass(FilterToHandlerAdapter.groovy)
    at org.grails.plugins.web.filters.FilterToHandlerAdapter.<init>(FilterToHandlerAdapter.groovy:63)
    at org.grails.plugins.web.filters.FiltersGrailsPlugin.reloadFilters(FiltersGrailsPlugin.groovy:195)
    at org.grails.plugins.web.filters.FiltersGrailsPlugin.doWithApplicationContext(FiltersGrailsPlugin.groovy:72)
    at org.grails.plugins.DefaultGrailsPlugin.doWithApplicationContext(DefaultGrailsPlugin.java:523)
    at org.grails.plugins.AbstractGrailsPluginManager.doPostProcessing(AbstractGrailsPluginManager.java:224)
    at grails.boot.config.GrailsApplicationPostProcessor.onApplicationEvent(GrailsApplicationPostProcessor.groovy:246)
    at grails.boot.config.GrailsApplicationPostProcessor.onApplicationEvent(GrailsApplicationPostProcessor.groovy)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:167)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:383)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:337)
    at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:882)
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.finishRefresh(EmbeddedWebApplicationContext.java:144)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:545)
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:762)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:372)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:316)
    at grails.boot.GrailsApp.run(GrailsApp.groovy:83)
    at grails.boot.GrailsApp.run(GrailsApp.groovy:388)
    at grails.boot.GrailsApp.run(GrailsApp.groovy:375)
    at grails.boot.GrailsApp$run.call(Unknown Source)
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:133)
    at app6.Application.main(Application.groovy:8)

【问题讨论】：

不错的堆栈跟踪！你的项目中有代码吗？
刚刚创建的 3.2 应用，带有这个 hello world 过滤器：$ cat grails-app/controllers/app6/Filter1Filters.groovy package app6 class Filter1Filters { def filters = { f1(controller: '*', action: '*') { before = { println "!!" } } } }
嘿@Ivan，你找到解决办法了吗？
不，我最终重写为 Grails 3 拦截器

标签： grails

【解决方案1】：

相同的文档sez：

这些仍然受支持

这意味着您仍然可以按原样使用它们。弃用意味着您应该开始考虑用拦截器替换它们。

【讨论】：