java - spring mvc 过滤器异常说response.getWriter已经被调用了

Question

一个简单根据session过滤结果的过滤器,代码如下:

@Configuration
public class WebMvcConfigurer extends WebMvcConfigurerAdapter {
  private String deniy="{denied:需要登陆}";
  public void addInterceptors(InterceptorRegistry registry) {
      registry.addInterceptor(new HandlerInterceptorAdapter() {

          @Override
          public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
                                   Object handler) throws Exception {              
            
              if(request.getSession().getAttribute("user")==null)
                  {
                
                  OutputStream write=response.getOutputStream();
                  write.write(deniy.getBytes("UTF-8"));
                  write.flush();               
                  write.close();  
                  return false;
                  }
       
              return true;
          }
      }).addPathPatterns("/add/*").addPathPatterns("/update/*").addPathPatterns("/del/*");
  }
}


可spring框架说输出流已经被获取过了,可我就这么一个过滤器啊,而且return false后应该不会进一步进入控制器处理吧?

Answer 1

不要直接使用OutputStream，使用PrinterWriter

PrintWriter printWriter = response.getWriter();
printWriter.write("DENY");
printWriter.flush();
return false;