使用过滤器取消页面请求时，Grails会引发404错误 [英] Grails throws a 404 error when canceling a page request with a filter

问题描述

  class MyFilters {
 def filters = {
 before = { 
 render（view：/ test）
 return false 
} 
} 
} 
  

这对于我使用控制器来处理请求的页面很有效，显示test.gsp的内容而不是我请求的页面。但是，当我尝试访问直接映射到GSP文件的页面时，出现404错误。

将渲染更改为 render test会产生相同的结果，就像注释掉它一样，只留下 return false 。

解决方案

Grails是一个MVC框架。如果您想直接将URL映射到GSP（不通过控制器和操作进行重定向），则需要在 UrlMappings.groovy 中对grails进行解释。在那里你可以定义你的快捷方式。例如：

  static mappings = {
/ $ viewName（view：/ index）{
约束{
 viewName（[一些约束]）
} 
} 
} 
  

这将在不经过控制器的情况下渲染 views / index.gsp 。如果您没有为这些URL定义控制器映射（或至少一个视图映射），则不能使用grails过滤器：

如果您确实想拦截所有请求，您可以像这样为您的grails应用程序添加一个servlet过滤器：

  import javax.servlet。* 
 
 import org.springframework.web.context.support.WebApplicationContextUtils; 
 $ b $ class TestFilter implements Filter {
 
 def applicationContext 
 
 void init（FilterConfig config）throws ServletException {
 applicationContext = WebApplicationContextUtils.getWebApplicationContext（ config.servletContext）
} 
 
 void destroy（）{
} 
 
 void doFilter（ServletRequest请求，ServletResponse响应，FilterChain链）throws IOException， ServletException {
 
 System.out.println（this filter has called called）; 
 
 
 
 
 
 
 $ p在这里你可以根据你的重定向或渲染 applicationcontext 和当前请求。
 
 
 
您需要将此过滤器添加到 web.xml 中。在如何做到这一点，看看：我如何在我的grails应用程序中使用servlet？ 
 
I have a filter:
class MyFilters {
    def filters = {
        before = {
            render(view: "/test")
            return false
        }
    }
}
This works great on pages where I'm using a controller to handle the request, showing the contents of test.gsp instead of the page I requested. However, when I try to access a page that maps directly to a GSP file, I get a 404 error.

Changing the render to simply render "test" produces the same results, as does commenting it out and just leaving the return false.
解决方案
Grails is a MVC framework. If you want to map an URL directly to a GSP (without redirection through a controller and action) you need to explain this to grails within your UrlMappings.groovy. There you can define your "shortcuts". E.g.:
static mappings = {
    "/$viewName"(view:"/index") {
        constraints {
            viewName([some constraints])
        }
    }
}
Which will render views/index.gsp without going through a controller.  If you do NOT define a controller mapping (or at least a view mapping) for those URLs, you canNOT use grails filters:

If you really want to intercept ALL requests, you can add a servlet filter to your grails application like this:
import javax.servlet.*

import org.springframework.web.context.support.WebApplicationContextUtils;

class TestFilter implements Filter {

    def applicationContext

    void init(FilterConfig config) throws ServletException {
        applicationContext = WebApplicationContextUtils.getWebApplicationContext(config.servletContext)
    }

    void destroy() {
    }

    void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

        System.out.println("this filter has been called");
    }
}
In here you can do your redirections or renderings based on the applicationcontext and the current request.

You need to add this filter to your web.xml. On how to do this, have a look at: How do i use a servlet in my grails app?

                        
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