特定于请求参数的 Java 过滤器 URL 模式 [英] Java Filter URL pattern specific to request params
问题描述
我们有一种情况,我们想对包含一些特定请求参数的 URL 使用过滤器,例如:
<前>http://mydomain.com/?id=78&formtype=simple_form&......http://mydomain.com/?id=788&formtype=special_form&...... 等等,id
是在运行时获取的,我想在 web.xml
中配置过滤器,只有 formtype=special_form
.应该如何实现解决?过滤器可以配置正则表达式吗?
据我所知,没有直接在 web.xml
中通过查询字符串将请求匹配到过滤器的解决方案.因此,您可以使用 init-params 在您的 web.xml
中注册过滤器以使过滤器可配置并通过 void init(FilterConfig filterConfig)
在您的 中设置模式javax.servlet.Filter
实现.
package mypackage;导入 java.io.IOException;导入 javax.servlet.Filter;导入 javax.servlet.FilterChain;导入 javax.servlet.FilterConfig;导入 javax.servlet.ServletException;导入 javax.servlet.ServletRequest;导入 javax.servlet.ServletResponse;导入 javax.servlet.http.HttpServletRequest;公共类 MyFilter 实现过滤器 {私有字符串模式;@覆盖公共无效销毁(){//TODO 自动生成的方法存根}@覆盖public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)抛出 IOException,ServletException {//检查我们是否有一个 httpServletRequest 和一个模式if (this.pattern != null && request instanceof HttpServletRequest) {//从 httpServletRequest 解析查询字符串String queryString = ((HttpServletRequest) request).getQueryString();//检查查询字符串是否存在并匹配给定的模式if (queryString != null && queryString.matches(pattern)) {//TODO 做一些特别的事情}}chain.doFilter(请求,响应);}@覆盖public void init(FilterConfig filterConfig) 抛出 ServletException {this.pattern = filterConfig.getInitParameter("pattern");}}
您的 web.xml 中的配置如下所示:
<过滤器><filter-name>myFilter</filter-name><filter-class>mypackage.MyFilter</filter-class><初始化参数><param-name>模式</param-name><param-value>{{PATTERN HERE}}</param-value></init-param></过滤器><过滤器映射><filter-name>myFilter</filter-name><url-pattern>/*</url-pattern></过滤器映射>
进一步阅读:
http://java.sun.com/javaee/5/docs/api/javax/servlet/Filter.html
We have a situation where we want to use filter for URL's containing some specific request parameters, e.g:
http://mydomain.com/?id=78&formtype=simple_form&....... http://mydomain.com/?id=788&formtype=special_form&.......
and so on, id
are fetched at run time, I want configure filter in web.xml
only if formtype=special_form
. How should achieve the solution? Can Filter be configured with regex patterns?
As far as I know there is no solution for matching requests to filters by query string directly in web.xml
. So you could register the filter in your web.xml
using init-params to make the filter configurable and set a pattern via void init(FilterConfig filterConfig)
in your javax.servlet.Filter
implementation.
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");
}
}
The configuration would look like this in your web.xml:
<!-- 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>
Further readings:
http://java.sun.com/javaee/5/docs/api/javax/servlet/Filter.html
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