使请求参数绑定不区分大小写

Question

我有一个要求，即使参数名称的情况发生变化，我也必须使 requestParams 正确绑定。注意：我使用的是spring 3.2

例如：http://localhost:8080/sample/home?**userName**=xxx 或 http://localhost:8080/sample/home?用户名=xxx 或 http://localhost:8080/sample/home?usernaMe=xxx 应该正确映射到我的 @RequestParam 值。

@RequestMapping(value = "home", method = RequestMethod.GET)
public goToHome(@RequestParam(value = "userName", required = false) String userName) {

}

三个url都应该调用上述方法并正确绑定用户名。 请给我有关如何通过实现新的参数处理程序解析器来实现这一点的建议？重写 spring 配置类以实现一般性优于更改所有 @RequestParam 的代码中的逻辑。

Answer 1

Spring 有一个LinkedCaseInsensitiveMap，您可以使用它来进行不区分大小写的查找。

实现可能如下所示。

package biz.deinum.web.filter;

import org.springframework.util.LinkedCaseInsensitiveMap;
import org.springframework.web.filter.OncePerRequestFilter;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Map;

/**
 * Wrapper for an {@link HttpServletRequest} to make the lookup of parameters case insensitive. The functionality
 * is achieved by using the {@link LinkedCaseInsensitiveMap} from Spring.
 * 
 * @author Marten Deinum
 */
public class CaseInsensitiveRequestFilter extends OncePerRequestFilter {
    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
        filterChain.doFilter(new CaseInsensitiveHttpServletRequestWrapper(request), response);
    }

    private static class CaseInsensitiveHttpServletRequestWrapper extends HttpServletRequestWrapper {

        private final LinkedCaseInsensitiveMap<String[]> params = new LinkedCaseInsensitiveMap<>();

        /**
         * Constructs a request object wrapping the given request.
         *
         * @param request
         * @throws IllegalArgumentException if the request is null
         */
        private CaseInsensitiveHttpServletRequestWrapper(HttpServletRequest request) {
            super(request);
            params.putAll(request.getParameterMap());
        }

        @Override
        public String getParameter(String name) {
            String[] values = getParameterValues(name);
            if (values == null || values.length == 0) {
                return null;
            }
            return values[0];
        }

        @Override
        public Map<String, String[]> getParameterMap() {
            return Collections.unmodifiableMap(this.params);
        }

        @Override
        public Enumeration<String> getParameterNames() {
            return Collections.enumeration(this.params.keySet());
        }

        @Override
        public String[] getParameterValues(String name) {
            return (String[])params.get(name);
        }
    }
}

Answer 2

您可以编写一个 servlet 过滤器来执行此操作。但它确实需要一些编码工作。

这里是代码的链接 - http://www.acooke.org/cute/Forcinglow0.html

类似这样的东西 - 在这个 servlet 过滤器中将参数转换为小写

public final class LowerCaseParametersFilter implements Filter {
 @Override
public void doFilter(final ServletRequest request,
                     final ServletResponse response,
                     final FilterChain chain)
        throws IOException, ServletException {
    if (request instanceof HttpServletRequest) {
        LOG.debug("Wrapping request");
        chain.doFilter(new LowerCaseRequest((HttpServletRequest) request),
                       response);
    } else {
        LOG.warn(format("Not wrapping request: %s", request.getClass()));
        chain.doFilter(request, response);
    }
}
}

这是 xml 配置 - 你需要

 <bean id="delegatingFilter"
      class="org.springframework.web.filter.DelegatingFilterProxy"

      p:targetBeanName="lowerParams"/>
 <bean id="lowerParams"   
      class="com.isti.bss.mvc.LowerCaseParametersFilter"/>

我做了一些研究，发现了这个Case-insensitive query string request paramters

   public class HttpCustomParamFilter implements Filter
  {

   private static class HttpServletRequestCustomeWrapper extends HttpServletRequestWrapper
   {
       private String[] parameterValues;

    @Override
    public String[] getParameterValues(String name)
    {
        Map<String, String[]> localParameterMap = super.getParameterMap();

        // Handle case insensitivity of http request paramters like start, count, query, sort, filter etc.
        if (localParameterMap != null && !localParameterMap.isEmpty())
        {
            parameterValues = new String[localParameterMap.size()];
            for (String key : localParameterMap.keySet())
            {
                if (name.equalsIgnoreCase(key))
                    parameterValues = localParameterMap.get(key);
                else
                    parameterValues = null;
            }
        }
        return parameterValues;
    }

Answer 3

实现自定义过滤器的解决方案。

过滤器：

public final class CaseInsensitiveParametersFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) {
    }

    @Override
    public void destroy() {
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        if (request instanceof HttpServletRequest) {
            chain.doFilter(new CustomHttpServletRequestWrapper((HttpServletRequest) request), response);
        } else {
            chain.doFilter(request, response);
        }

    }

    private static class CustomHttpServletRequestWrapper extends HttpServletRequestWrapper {

        private Map<String, String[]> lowerCaseParams = new HashMap<>();

        public CustomHttpServletRequestWrapper(HttpServletRequest request) {
            super(request);
            Map<String, String[]> originalParams = request.getParameterMap();
            for (Map.Entry<String, String[]> entry : originalParams.entrySet()) {
                lowerCaseParams.put(entry.getKey().toLowerCase(), entry.getValue());
            }
        }

        @Override
        public String getParameter(String name) {
            String[] values = getParameterValues(name);
            if (values != null && values.length > 0) {
                return values[0];
            } else {
                return null;
            }
        }

        @Override
        public Map getParameterMap() {
            return Collections.unmodifiableMap(lowerCaseParams);
        }

        @Override
        public Enumeration getParameterNames() {
            return Collections.enumeration(lowerCaseParams.keySet());
        }

        @Override
        public String[] getParameterValues(String name) {
            return lowerCaseParams.get(name);
        }

    }

Servlet 初始化器：

public class RestServiceInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
    @Override
    protected Filter[] getServletFilters() {
        return new Filter[]{new CaseInsensitiveParametersFilter()};
    }
}