特定于请求参数的Java过滤器URL模式
我们遇到一种情况,我们想对包含某些特定请求参数的URL使用过滤器,例如:
http://mydomain.com/?id = 78&formtype = simple_form&......。 http://mydomain.com/?id = 788&formtype = special_form&......。
等等,id
都是在运行时牵强,我想配置过滤器,web.xml
只有当formtype=special_form
。应该如何解决?可以使用正则表达式模式配置Filter吗?
回答:
据我所知,尚无解决方案可直接在中通过查询字符串将请求匹配到过滤器web.xml
。因此,您可以在web.xml
使用init-
params的情况下注册过滤器,以使过滤器可配置,并void init(FilterConfig
filterConfig)在javax.servlet.Filter
实现中设置模式。
package mypackage;import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
public class MyFilter implements Filter {
private String pattern;
@Override
public void destroy() {
// TODO Auto-generated method stub
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
// check whether we have a httpServletRequest and a pattern
if (this.pattern != null && request instanceof HttpServletRequest) {
// resolve the query string from the httpServletRequest
String queryString = ((HttpServletRequest) request).getQueryString();
// check whether a query string exists and matches the given pattern
if (queryString != null && queryString.matches(pattern)) {
// TODO do someting special
}
}
chain.doFilter(request, response);
}
@Override
public void init(FilterConfig filterConfig) throws ServletException {
this.pattern = filterConfig.getInitParameter("pattern");
}
}
您的web.xml中的配置如下所示:
<!-- MyFilter --><filter>
<filter-name>myFilter</filter-name>
<filter-class>mypackage.MyFilter</filter-class>
<init-param>
<param-name>pattern</param-name>
<param-value>{{PATTERN HERE}}</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>myFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
- 进一步阅读:http
- //java.sun.com/javaee/5/docs/api/javax/servlet/Filter.html
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