<!-- 配置文件上传类型解析器 multipartResolver-->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
  <!-- 设置上传文件最大尺寸，单位为B -->
  <property name="maxUploadSize" value="5242880" />
</bean>

<!-- 1.在文件上传解析时发现异常，此时还没有进入到Controller方法中 -->
<bean id="exceptionResolver" class= "org.springframework.web.servlet.handler.SimpleMappingExceptionResolver"> 
  <property name="exceptionMappings"> 
    <props> 
    <!-- 遇到MaxUploadSizeExceededException异常时，跳转到error.jsp页面 -->
    <prop key= "org.springframework.web.multipart.MaxUploadSizeExceededException">/error </prop> 
    </props> 
  </property>
</bean>

/**
 * 自定义异常处理器类
 */
public class ExceptionHandler implements HandlerExceptionResolver{
  /**
   * 处理上传文件大小超过限制抛出的异常
   */
  @Override
  public ModelAndView resolveException(HttpServletRequest req,
      HttpServletResponse res, Object ob,Exception ex) {
    ModelAndView mv=new ModelAndView();
    //判断异常类型，来跳转不同页面
    if (ex instanceof MaxUploadSizeExceededException){ 
      //指定错误信息
      mv.addObject("errormessage", "上传文件过大");
      //设置跳转视图
      mv.setViewName("userEdit");
      return mv;
    } 
    //其他异常
    return null;
  }
}

<!-- 2.配置自定义异常处理器类 -->
<bean class="com.itheima.exception.ExceptionHandler" />

<!-- 配置文件上传类型解析器 multipartResolver-->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver" />

public class FileUploadInterceptor extends HandlerInterceptorAdapter {
  private long maxSize;

  @Override
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    //判断是否文件上传
    if(request!=null && ServletFileUpload.isMultipartContent(request)) {
      ServletRequestContext ctx = new ServletRequestContext(request);
      //获取上传文件尺寸大小
      long requestSize = ctx.contentLength();
      if (requestSize > maxSize) {
        //当上传文件大小超过指定大小限制后，模拟抛出MaxUploadSizeExceededException异常
        throw new MaxUploadSizeExceededException(maxSize);
      }
    }
    return true;
  }
  public void setMaxSize(long maxSize) {
    this.maxSize = maxSize;
  }
}

<mvc:interceptors>
  <mvc:interceptor>
    <mvc:mapping path="/**"/>
    <bean class="com.itheima.interceptor.FileUploadInterceptor">
      <!-- 设定限制的文件上传大小 -->
      <property name="maxSize" value="5242880"/>
    </bean>
  </mvc:interceptor>
</mvc:interceptors>

/**
 * 全局文件类型拦截器
 */
public class FileTypeInterceptor extends HandlerInterceptorAdapter {
  @Override
  public boolean preHandle(HttpServletRequest request, 
      HttpServletResponse response, Object handler)throws Exception {
    boolean flag= true;
    // 判断是否为文件上传请求
    if (request instanceof MultipartHttpServletRequest) {
      MultipartHttpServletRequest multipartRequest = 
          (MultipartHttpServletRequest) request;
      Map<String, MultipartFile> files = 
                    multipartRequest.getFileMap();
      Iterator<String> iterator = files.keySet().iterator();
      //对多部件请求资源进行遍历
      while (iterator.hasNext()) {
        String formKey = (String) iterator.next();
        MultipartFile multipartFile = 
               multipartRequest.getFile(formKey);
        String filename=multipartFile.getOriginalFilename();
        //判断是否为限制文件类型
        if (! checkFile(filename)) {
          //限制文件类型，请求转发到原始请求页面，并携带错误提示信息
          request.setAttribute("errormessage", "不支持的文件类型！");
          request.getRequestDispatcher("/WEB-INF/jsp/userEdit.jsp")
          .forward(request, response); 
          flag= false;
        } 
      }
    }
    return flag;
  }
  /**
   * 判断是否为允许的上传文件类型,true表示允许
   */
  private boolean checkFile(String fileName) {
    //设置允许上传文件类型
    String suffixList = "jpg,gif,png,ico,bmp,jpeg";
    // 获取文件后缀
    String suffix = fileName.substring(fileName.lastIndexOf(".")
        + 1, fileName.length());
    if (suffixList.contains(suffix.trim().toLowerCase())) {
      return true;
    }
    return false;
  }
}

<mvc:interceptors>
  <!-- 如果有多个拦截器，则按照顺序进行配置 -->
　　<mvc:interceptor>
    <!-- /**表示所有URL和子URL路径 -->
    <mvc:mapping path="/**" />
    <!-- 配置自定义的文件上传类型限制拦截器 -->
    <bean class="com.itheima.interceptor.FileTypeInterceptor" />
  </mvc:interceptor>
</mvc:interceptors>