Spring 实现请求 URL 和参数名称的不区分大小写

URL 不区分大小写

spring mvc 对于请求 URL 默认是区分大小写的。

如定义一个 controller，其请求 path 为/welcome。

@Controller
public class HomeController {

@RequestMapping(value = "/welcome", method = RequestMethod.GET)
 public String printWelcome(@RequestParam String who,ModelMap model) {
  model.addAttribute("message", "welcome "+who);
  return "hello";
 }
}

本地访问该路径，如：

1. http://localhost:8080/welcome
2. http://localhost:8080/Welcome

则，第一个 URL 可以成功访问，而访问第二个 URL 则返回 404 错误。

分析：

URL 请求到达 DispatcherServlet 时，会使用 RequestMappingHandlerMapping 查找 URL 匹配的 HandlerMethod。其中，会用到 RequestMappingHandlerMapping 的基类 AbstractHandlerMappingPathMatcher 的 PathMatcher 属性进行 URL 映射处理。RequestMappingHandlerMapping 类默认使用 AntPathMatcher 作为 PathMatcher，通过设置 AntPathMatcher 的 CaseSensitive 属性为 false，来指定 PathMatcher 对 URL 的大小字母不敏感。

解决：

code-based configuration

import org.springframework.context.annotation.Configuration;
import org.springframework.util.AntPathMatcher;
import org.springframework.web.servlet.config.annotation.PathMatchConfigurer;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;
/**
 * WebConfig url忽略大小写
 */
@Configuration
public class SpringWebConfig extends WebMvcConfigurationSupport {
    @Override
    public void configurePathMatch(PathMatchConfigurer configurer) {
        AntPathMatcher matcher = new AntPathMatcher();
        matcher.setCaseSensitive(false);
        configurer.setPathMatcher(matcher);
    }
}

参数名称不区分大小写

通过 filter 机制，创建 HttpServletRequest 的子类，重写获取请求参数的方法，使参数值的获取不区分参数名称大小写。最后，配置 Filter。

import java.io.IOException;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Map;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
import org.springframework.util.LinkedCaseInsensitiveMap;
import org.springframework.web.filter.OncePerRequestFilter;

public class CaseInsensitiveRequestParameterNameFilter extends OncePerRequestFilter {

 @Override
 protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
   throws ServletException, IOException {
  filterChain.doFilter(new CaseInsensitiveParameterNameHttpServletRequest(request), response);
 }

 public static class CaseInsensitiveParameterNameHttpServletRequest extends HttpServletRequestWrapper {
  private final LinkedCaseInsensitiveMap<String[]> map = new LinkedCaseInsensitiveMap<>();

  @SuppressWarnings("unchecked")
  public CaseInsensitiveParameterNameHttpServletRequest(HttpServletRequest request) {
   super(request);
   map.putAll(request.getParameterMap());
  }

  @Override
  public String getParameter(String name) {

   String[] array = this.map.get(name);
   if (array != null && array.length > 0)
    return array[0];
   return null;
  }

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

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

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

代码配置 Filter

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
import com.company.project.web.filter.CaseInsensitiveRequestParameterNameFilter;

public class SpringWebInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

 @Override
 protected Class<?>[] getRootConfigClasses() {
  return new Class<?>[] { SpringRootConfig.class };
 }

 @Override
 protected Class<?>[] getServletConfigClasses() {
  return new Class<?>[] { SpringWebConfig.class };
 }

 @Override
 protected String[] getServletMappings() {
  return new String[] { "/" };
 }

 @Override
 public void onStartup(ServletContext servletContext) throws ServletException {
  super.onStartup(servletContext);
  Dynamic filter = servletContext.addFilter(CaseInsensitiveRequestParameterNameFilter.class.getSimpleName(),
    CaseInsensitiveRequestParameterNameFilter.class);
  filter.addMappingForUrlPatterns(null, true, "/*");
 }
}

启动程序，访问http://localhost:8080/WELCOME?wHo=me 试试吧