Required request body is missing拦截器

当在拦截器中需要对POST请求的参数进行处理时，有时会出现"Required request body is missing"异常。这是因为POST请求中的参数以流的形式存在，流数据只能读取一次。为了解决这个问题，可以使用HttpServletRequestWrapper来包装HttpServletRequest，这样可以将流保存起来，使参数能够多次读取。通过实现一个自定义的HttpServletRequestWrapper类，我们可以在拦截器中对请求参数进行处理，避免出现参数丢失的异常。

下面是一个示例拦截器的代码：

@Order(1)
@WebFilter(filterName="koalaSignFilter",urlPatterns="/*")
public class KoalaSignFilter implements Filter{
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        // do nothing
    }
    
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        ServletRequest requestWrapper=null;
        if(request instanceof HttpServletRequest) {
            requestWrapper=new KoalaHttpRequestWrapper((HttpServletRequest)request);
        }
        if(requestWrapper==null) {
            chain.doFilter(request, response);
        }else {
            chain.doFilter(requestWrapper, response);
        }
    }
    
    @Override
    public void destroy() {
        // do nothing
    }
}

在这个示例中，我们通过KoalaHttpRequestWrapper类来包装HttpServletRequest，并将包装后的request对象传递给FilterChain进行处理。这样就能够解决"Required request body is missing"异常问题。

总结来说，解决"Required request body is missing"拦截器的方法是通过使用HttpServletRequestWrapper包装HttpServletRequest，使得参数流能够多次读取。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
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