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使请求参数绑定不区分大小写

问题内容：

我有一个要求，即使参数名称的大小写发生变化，我也必须使requestParams正确绑定。注意：我正在使用Spring 3.2

例如：http://localhost:8080/sample/home?* userName =
xxx或http://localhost:8080/sample/home?
username = 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) {

}

这三个网址都应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此建议。覆盖Spring配置类以实现一般性优先于更改所有@RequestParam的代码中的逻辑。


问题答案：

Spring有一个LinkedCaseInsensitiveMap您可以用来执行不区分大小写的查找的功能。

一个实现可能如下所示。

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);
        }
    }
}